Technical Manual 2025

Technical Manual 2025
Table of Contents
Services
Table of Contents
Materials and Process Engineering
Table of Contents
Seals for Rotary Applications
Table of Contents
Seals for Fluid Power Applications – Hydraulics
Table of Contents
Seals for Fluid Power Applications – Pneumatics
Table of Contents
Static Seals
Table of Contents
Special Sealing Products
Table of Contents
Hydraulic Accumulators
Table of Contents
Boots & Bellows
Table of Contents
Diaphragms
Table of Contents
Stuffing Box Packings
Table of Contents
Index

The information contained in this Technical Manual is based on decades of research into the development and manufacture of seals by the Freudenberg Group and re- flects the current state of knowledge. This Technical Manual and the information con- tained therein apply exclusively to Freuden- berg brand products. Products of the Dich- tomatik brand have not been taken into account in preparing this manual. The sealing effect of many products is not produced solely by the component itself, however. Depending on the specific appli- cation, it depends to a large extent on the other parameters, such as installation and mating point, pressurization, operating temperature, the media to be sealed, lubrication and possible accumulation of dirt from the outside. These and other factors can have a marked influence on the function of the seals when they are put to practical use. With this in mind, it is not possible to make general statements about how Freudenberg products function. The infor mation in this manual is intended only as a general, non-binding guide and is not valid for every application. It is rec- ommended that specific applications be discussed with the experts at Freuden- berg Sealing Technologies. In the case of particularly high and special loads, such as those caused by aggressive media, the seal should be selected in close cooperation and after consultation. In this context, tests to verify the functional reliability are usually indispensable. In the course of optimizing its products, Freudenberg Sealing Technologies re- serves the right to change the product range, production sites, products and their manufacturing processes as well as the information in this manual without prior notice. All previous publications become invalid with the publication of this edition. Reproduction in any form requires the express permission of Freudenberg FST GmbH, 69465 Weinheim, Germany. © Freudenberg FST GmbH All rights reserved. Registered trademarks of Simmerring®, Merkel®, Seventomatic®, Simriz®, Quantum® and Freudenberg Xpress® are globally protected, further registrations are possible. AdBlue®: AdBlue® is a registered trademark of VDA. Bonderite® / P3®: Bonderite® and P3® are registered trademarks of Henkel. The trademarks are identified on the basis of the information provided by the respec- tive rights holder and in accordance with that information. The use of the trade- marks is for informational purposes only and shows or explains the requirements or technical effects described in the text. Un- der no circumstances does the reference to the trademarks imply any business rela- tionship or other connection or endorse- ment by the respective rights holder of the trademarks. We do not accept any respon- sibility for the accuracy of the trademark protection information in different regions. The user-friendliness of this technical manual has been improved for you as a reader by integrating cross-references to other chapters and including important notes and links to external media, thus ensuring a holistic view of sealing tech- nology. Play-circle  Link to video Map-marker-edit Map-Marker-Exclamation Important Note Valuable information

TABLE OF CONTENTS Table of Contents 1. INTRODUCTION & SERVICES 2. MATERIALS AND PROCESS ENGINEERING 3. SEALS FOR ROTARY APPLICATIONS 4. SEALS FOR FLUID POWER APPLICATIONS – HYDRAULICS 5. SEALS FOR FLUID POWER APPLICATIONS – PNEUMATICS 6. STATIC SEALS 7. SPECIAL SEALING PRODUCTS 8. HYDRAULIC ACCUMULATORS 9. BOOTS & BELLOWS 10. DIAPHRAGMS 11. STUFFING BOX PACKINGS 12. INDEX 7 29 223 415 535 585 645 709 739 759 811 863 & N O I T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 1 X E D N I

Company COMPANY The Freudenberg Group was founded in 1849 and is still family-owned, making it independent, long-term oriented and responsible in its actions. Today, Freudenberg is a broadly diversified global Group. While Freudenberg & Co. Kommanditgesellschaft represents the strategic management company, Freuden- berg SE as the operational management company reflects the global nature of the Freudenberg Group. Freudenberg is divided into Business Groups that operate in a wide range of in- dustries. From Vileda® brand household products to technically complex sealing solutions, the company is always regarded as an innovation and technology leader. The Group’s strong segmentation has a single objective: to be close to the cus- tomer and to meet the demands made on a market expert. Its many research and development facilities ensure the company’s long-term success and enable a rapid response to market and customer- specific changes. Freudenberg Sealing Technologies (here- inafter also abbreviated FST) is the larg- est Business Group in the Freudenberg Group and forms part of the Seals and Vibration Control Technology Division. It is a supplier, as well as a development and service partner to customers in a wide range of market segments, the automo- tive industry, civil aviation, mechanical engineering and shipbuilding, the food and pharmaceutical industries and the agricultural and construction machinery industries, for example. Freudenberg website Freudenberg Sealing Technologies website 2

Company trial standards. The two-brand strategy is part of the comprehensive service port- folio and guarantees a full range of seals and product-related services. The unique range of services in the field of sealing technology sets standards for quality, functionality and cost-effective- ness in general industry. With its compre- hensive product range and broad range of services (→ chapter “Services”, page 7), Freudenberg Sealing Technologies offers a service package that is unique in the market – for virtually any application. FST puts its leading technological expertise to profitable use for its customers: Their complete systems are analyzed and the individual components are optimally matched to each other. In this way, they receive exactly the solution that best meets their needs – economically and reliably. Strengthened by time- and cost-saving single sourcing, customers will find their ideal partner for all sealing applications in Freudenberg Sealing Technologies, even for more complex systems. For decades, FST’s unique material exper- tise is a key success factor for the out- standing performance and continuous technological edge of its products. This is reflected in well-known product groups such as Simmerrings, fluid technology products, hydraulic accumulators, O-rings and liquid silicone products that form the world’s largest product range for all appli- cations in general industry. Since the 1980ies, Freudenberg Sealing Technologies is strategically expanding its portfolio to embrace the growing demands of e-mobility and green energy. The company is leveraging its extensive expertise in sealing solutions to support the development of electric vehicles (EVs) and sustainable energy systems. By focusing on innovative materials and advanced technologies, Freudenberg Sealing Technologies is enhancing the performance and reliability of EV compo- nents, such as battery systems and elec- tric drivetrains. In addition, the company is developing specialized sealing solu- tions for renewable energy applications, including wind turbines, solar panels, and hydrogen fuel cells. These solutions are designed to withstand harsh environ- mental conditions and ensure the longev- ity and efficiency of green energy systems. By driving innovation in this field, Freudenberg Sealing Technologies is contributing to the transition towards a more sustainable energy landscape, helping to reduce greenhouse gas emissions and promote environmental protection. Starting with the Simmerring® developed at Freudenberg in 1932, FST today has a broad, consistently customer-oriented product portfolio of sealing technology ranging from standard parts and custom- ized individual solutions to complete sealing packages. Together with its part- ners NOK Corporation, Japan, Freuden- berg-NOK, India, and NOK-Freudenberg Group, China, Freudenberg Sealing Tech- nologies forms a global network with the objective of offering products of the same high quality worldwide. The FST portfolio is rounded off by Dichtomatik brand products that reliably meet indus- & N O I T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 3 X E D N I

As part of the Freudenberg Group, Freudenberg Sealing Technologies draws on in-depth in-house research, and ex- pertise in development and production, to continually extend its technological lead through innovative solutions – for the benefit and in the service of custom- ers worldwide with their local market re- quirements. The extensive sales network provides reliable local support to its more than 100,000 customers in all industrial markets on all continents. THE FREUDENBERG SEALING TECHNOLOGIES RANGE OF SERVICES AT A GLANCE y World’s largest product range in sealing technology Integrated solutions from a single source y Permanent innovations Technological edge to give custom- ers a competitive advantage, thanks to specially developed products and materials y Unique materials expertise and high-quality standards Leading know-how for reliable and economical applications y Wide range of integrated services Partnership-based support from development, e.g. with the aid of FEM designs or tests on in-house test benches, through to long-term product use y Think global, act local Global expertise with knowledge of the local market requirements Company 4

Sustainability CO2 30% reduction in tons of CO2 / per million euros of revenue by 2025 Sustainability at Freudenberg & N O I T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A Freudenberg’s approach includes electri- fying its energy supply and minimizing CO2 emissions in manufacturing process- es. In addition, FST is dedicated to sustain- able production and business practices. The company emphasizes resource effi- ciency, focusing on reducing energy and material consumption. Its sustainability strategy also involves developing prod- ucts that help customers operate more efficiently and sustainably. S W O L L E B & S T O O B Sustainability at Freudenberg Sealing Technologies S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 5 X E D N I SUSTAINABILITY The sustainability of products and pro- cesses has always been part of Freuden- berg’s lived responsibility. In 2016, the Freudenberg Group developed a world- wide sustainability strategy that was handed over to all Business Groups, in- cluding Freudenberg Sealing Technologies, as a framework in 2017. In addition, sustainability was made a systematic component of the strategy process. Freudenberg Sealing Technologies is deeply committed to sustainability, with a clear focus on reducing its environmental impact. The company has set ambitious goals to cut its relative CO2 emissions by 30% from 2020 to 2025. By 2030, it aims to use exclusively renewable electricity sources. This commitment is part of a broader strategy to achieve carbon neu- trality through energy efficiency, waste reduction, and the optimization of mate- rials and technologies.

Initial projects and measures have shown that even small changes have a major im- pact on achieving climate targets. 100% green electricity by 2030 regions such as India, for example. The picture is also not uniform when it comes to materials. Some can be recycled, others such as elastomers (rubber) cannot. The three most important fields of action for all Business Groups are: Energy Effi- ciency, CO2 Emissions and Waste. Group- wide key performance indicators have been introduced for these areas, which have since created transparency on im- provements in these areas and help drive sustainability at Freudenberg. The five topics of materials, waste, energy, emissions and water are of the greatest rel- evance to the Group as a whole, although not all topics have the same significance for all Business Groups. Water, for exam- ple, is hardly used by some Business Groups, while it plays a major role in others, when production is located in water- scarce carbon neutrality by 2045 Sustainability 6

S E R V C E S I 7 INDEX STUFFING BOX PACKINGS DIAPHRAGMS BOOTS & BELLOWS HYDRAULIC ACCUMULATORS SPECIAL SEALING PRODUCTS STATIC SEALS FLUID POWER APPLICATIONS – PNEUMATICS FLUID POWER APPLICATIONS – HYDRAULICS SEALS FOR ROTARY APPLICATIONS S e r v i c e s INTRODUCTION & SERVICES MATERIALS AND PROCESS ENGINEERING

Table of contents TABLE OF CONTENTS 1. DESIGN AND ENGINEERING 2. COATING 3. LUBE & SEAL 4. PRODUCT MODIFICATION 5. INSTALLATION AND DEINSTALLATION AIDS 6. PRODUCT MARKING 7. DAMAGE ANALYSIS 8. TEST BENCHES 9. LABORATORY TESTS 10. TRAINING 11. LC FREUDENBERG XPRESS® CUSTOMIZED SOLUTIONS 12. ONLINE TOOLS 8 10 11 12 13 14 15 16 17 18 19 20 24

SERVICES Services Expertise in all process areas, from re- search and development, materials and manufacturing to customer-oriented sales: this is the guarantee for our unique know-how and a product range of the highest quality. Conveying this knowl- edge directly and transparently to custom- ers is the goal of the services provided by Freudenberg Sealing Technologies (here- inafter also abbreviated FST). This Technical Manual presents a selection of current service points, whereby the focus is on services with a technical back- ground. For example, it is possible to adapt prod- ucts to your individual requirements by making modifications or applying coatings or markings. As a special service, FST has a fully comprehensive damage analysis department and one of the most modern accredited test laboratories. Expanding this knowledge and imparting it to you is possible in a joint dialog through the FST Academy. The wide range of services Freudenberg Sealing Technologies offers is rounded off by a variety of online services. Here, a wide range of selection options are avail- able to you via selectors or configurators, thus enabling you to make an easy and uncomplicated initial choice of the sealing solution. You can then order the prod ucts yourself in just a few steps via the product catalog and the EASY online ordering platform. Please visit the FST homepage for a complete overview of the services avail- able. FST Services & N O I T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 9 X E D N I

Services – Design and Engineering DESIGN AND ENGINEERING ENGINEERS MAINTENANCE PURCHASING/QM Questioning complex issues and understanding interrelationships is reflected in Freudenberg Seal- ing Technologies’ research and development centers worldwide, and it is hardly by chance that the word “innovation” is in the Freudenberg logo. FST lives this directly with its customers like only few other companies do. The network of highly qualified sealing technology employees – from product developers to application engineers – is quite unique. Specialists on individual segments or at the product level are available to customers worldwide. A closed value chain is the guarantee for targeted and precise support. From the developer of the compound formulation to the product developer, Freudenberg Sealing Technologies has all the ca- pabilities of efficient engineering. This bundled know-how, supplemented by subse- quent services such as various online tools or in- ternal testing facilities, enables holistic support for development projects. Here, FST grows together with its customers through the challenges of sealing technology. Would you like to learn more about Freudenberg Sealing Technologies’ products and services? Then get in touch with the person you normally deal with or use the contact options on fst.com. Design and Engineering VORTEILE IM ÜBERBLICK BENEFITS AT A GLANCE y Vorteil 1 y Highly qualified contacts y y Product- and/or application-specific y y Available worldwide y Also personally on site 10

Services – Coating & N O I T C U D O R T N I S E C I V R E S COATING D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A In addition to reducing friction, colorable bonded coatings make it easy to visually distinguish be- tween similar or identical seal dimensions. This drastically reduces the risk of confusion during installation. To meet the ever-increasing importance of the e-mobility sector, FST oﬀers the electrically con- ductive coating “EMI Shielding.” For further information, see also → chapter “Static Seals – 9. Modiﬁcations” on page 620. Excerpt of coating types Play-circle  Coating ENGINEERS MAINTENANCE PURCHASING/QM In addition to a wide range of products, Freuden- berg Sealing Technologies oﬀers its customers many diﬀerent options for environmentally friendly and standard-compliant high-performance coat- ings. Here, too, consistently high quality is ensured by relying on standardized processes and modern production. Freudenberg Sealing Technologies already applies a wide variety of coatings to well over 350 million parts a year. A coating can not only make assembly easier and thus increase the service life, but also optimize lubrication properties. A wide variety of coating options are available for this purpose. Coatings are also an eﬀective aid for stick-slip-free behavior and lower breakaway torques. S C I L U A R D Y H S C I T A M U E N P R E W O P D U L F I R E W O P D U L F I – S N O T A C I I L P P A – S N O T A C I I L P P A S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B VORTEILE IM ÜBERBLICK BENEFITS AT A GLANCE y Vorteil 1 y Optimization of lubricating properties y y Stick-slip-free y y Lower breakaway torques y For automated assembly y Silicone and paint wetting interference-free y Non-stick eﬀect y EMI shielding y Technical cleanliness y Increase/guarantee of process reliability S M G A R H P A D I X O B G N I F F U T S I S G N K C A P X E D N I 11 11

Services – Lube & Seal LUBE & SEAL ENGINEERS MAINTENANCE PURCHASING/QM Lube & Seal: two worlds under one roof Sealing specialist meets lubricant expert – Simmer- ring® meets lubricant: the idea of harmonizing these two worlds and their chemical formulations is quite obvious. After all, it is only by taking a holistic view of the tribological sealing system – in particular the interaction between the sealing element and the lubricant – that it is possible to develop long-lasting and reliable sealing systems in drive technology. With Lube & Seal, the sealing specialist Freuden- berg Sealing Technologies and the lubricant expert Klüber Lubrication have combined their respective specific know-how to form comprehensive 12 Freudenberg technology expertise. Only Freuden- berg Sealing Technologies offers this comprehen- sive and unique service for optimizing sealing systems. Lube & Seal VORTEILE IM ÜBERBLICK BENEFITS AT A GLANCE y Vorteil 1 y Cost savings due to up to 25% longer functional y y y Safeguarding of warranty statements to the and service life end customer y Increased customer satisfaction through re- duced failure rates y Competitive advantages through a “Lube & Seal certified” sealing system

Services – Product Modiﬁcation & N O I T C U D O R T N I S E C I V R E S PRODUCT MODIFICATION D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A A compilation of the most common options, such as mechanical reworking or optimization of the spring contact forces for Simmerring® rotary shaft seals, has been compiled online for you. Please use the QR code provided for this purpose. For further information, see also → chapter “Seals for rotary applications – 9. Modiﬁed catalog goods” on page 333. FST Sales Sheet Modiﬁed Catalog Program ENGINEERS MAINTENANCE PURCHASING/QM A wide range of modiﬁcation options to meet individual product requirements With a wide range of dimensions, designs and ma- terials, the Freudenberg Sealing Technologies cat- alog program oﬀers a broad spectrum of sealing solutions. Nevertheless, speciﬁc operating condi- tions may require a seal optimized for the applica- tion. Adequate adaptation due to changing environ- mental parameters or the extension of service li- fecycles is crucial for many customers and can thus be guaranteed. For this purpose, it is possible in some product groups to optimize the current products from the extensive catalog range by making modiﬁcations. S C I L U A R D Y H S C I T A M U E N P R E W O P D U L F I R E W O P D U L F I – S N O T A C I I L P P A – S N O T A C I I L P P A S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B VORTEILE IM ÜBERBLICK BENEFITS AT A GLANCE y Vorteil 1 y Extension of the service life y y Economically attractive y y Extension of the tool life y Optimization of functional reliability y Reduction of maintenance cycles S M G A R H P A D I X O B G N I F F U T S I S G N K C A P X E D N I 13

Services – Installation and Deinstallation Aids INSTALLATION AND DEINSTALLATION AIDS ENGINEERS MAINTENANCE PURCHASING/QM Tools for simple, fast and reliable installation and deinstallation of seals As diverse as the requirements for seals are, their installation is often just as complex. Whether it’s automatic assembly, directional or non-rotational, small or large, through to stiffness and deformabil- ity, everything plays a role. Special knowledge and tools are often needed. Freudenberg Sealing Technologies supports you with these challenges in a variety of ways – from arranging a personal contact on site to descriptive videos or the selection of one of the many prod- uct-specific aids and tools. 14 Play-circle  FST installation instructions VORTEILE IM ÜBERBLICK BENEFITS AT A GLANCE and humans y Vorteil 1 y Proper installation and deinstallation y y Avoidance of damage to the device, machine y y Warranty claims and image maintenance y Coordinated tools y Cost reduction

PRODUCT MARKING Services – Product Marking ENGINEERS MAINTENANCE PURCHASING/QM Clear marking ensures easy product identification and process reliability Freudenberg Sealing Technologies has always placed great importance on providing its custom- ers with comprehensive product information. From the manufacturing or batch number to the best-before date. This transparency is part of Freudenberg Sealing Technologies’ self-image of process reliability and quality assurance. In order to respond to your requirements even more specifically, labeling systems are offered for individualizing products. In order to ensure safety, optimization, high-level automation and quality control, markings are becoming more and more important and are a focus for customers. Other possible markings are: y Color markings to prevent mix-ups and support identification and traceability y Engravings that give seals individual branding and support identification and traceability y Printing provides additional labeling and facil- itates identification and traceability FST Product Marking VORTEILE IM ÜBERBLICK BENEFITS AT A GLANCE y Vorteil 1 y Branding according to customer requirements y y Traceability y y Simple and customer-specific identification y Reduction of mix-ups & N O I T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 15 X E D N I

Services – Damage Analysis DAMAGE ANALYSIS relevant application parameters. Product-specific questionnaires from Freudenberg Sealing Technol- ogies accelerate and simplify the analysis process. In conjunction with uncleaned failure samples or lubricant samples, they serve as a basis for further measures. At the beginning of damage analysis, the focus is usually on a visual inspection. Depending on the damage pattern, this is compared or verified by performing more in-depth analytical examina- tions. As a result, FST provides its customers with a documentation and evaluation of the findings including photos, followed by an action recom- mendation or remedial measures. Contact FST VORTEILE IM ÜBERBLICK BENEFITS AT A GLANCE y Vorteil 1 y Modern testing equipment y y Product and application specific know-how y y Access to in-depth expertise, such as material or product development y Experienced, highly qualified experts y Global network with local contacts ENGINEERS MAINTENANCE PURCHASING/QM Expert support reduces downtime and costs When elastomer seals fail, this usually leads to un- pleasant side effects such as downtime costs, complaints, or damage to reputation. However, clear traces can often be found on the seals that allow conclusions to be drawn about the damage mechanism. With the aid of state-of-the-art testing methods and equipment, Freudenberg Sealing Technologies is able to clearly analyze and isolate cases of dam- age. Often there is not just one cause of leakage. In many cases, it is only the interaction of a number of factors that leads to the damage pattern in question. For this reason, it is absolutely crucial for the damage analysis to have the user provide all 16

TEST BENCHES Services – Test Benches ENGINEERS MAINTENANCE PURCHASING/QM Development costs, time, process reliability and high-quality standards – all play an essential role in new or further development. Freudenberg Sealing Technologies continuously invests in new technologies to map the latest test methods. Always with the goal of avoiding cost-intensive trial runs and field tests. By working closely with the customer, FST is the only seal manufacturer to offer this added value across the entire product spectrum of sealing technology and its segments. Test Benches BENEFITS AT A GLANCE y Sealing tests under real conditions y Low development costs and fast development results y Optimized sealing concept (seal, shaft/rod, lubricant, application parameters) y Extended service life of all components y Verification of the service life requirement y Testing of your new and further develop- ments, prototypes & N O I T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 17 17 X E D N I

Services – Laboratory Tests LABORATORY TESTS Due to the direct proximity of material develop- ment, production, simulation and failure analysis, Freudenberg Sealing Technologies is able to take a comprehensive and globally unique approach that no other test laboratory can offer you. Over 170 years of experience, a continuously expand- ing database and a highly motivated team of ex- perts with the most modern testing facilities are waiting for you. Together with you, we will find the right tests and test parameters to solve your problem. Contact FST Laboratory Tests BENEFITS AT A GLANCE y Recognized laboratory with external quality y Vorteil 1 assurance through accreditation according to y DIN EN ISO/IEC 17025:2018 y y Material testing, materials and process know- how from a single source y Active participation in the design and estab- lishment of new testing methods y Individual, personal support, no matter whether it’s a standard test, a development-related question or analysis of damage ENGINEERS MAINTENANCE PURCHASING/QM What goes for the seal, goes for the test From conventional international standard tests to the most specialized elastomeric special tests, Freudenberg Sealing Technologies offers you a self-sufficient, certified and accredited test labo- ratory – with well over 200 tests from all relevant areas of rubber technology and their specific fea- tures. FST has adaptable test benches for specifications or specific questions that arise during develop- ment. This ensures that your general conditions are reproduced optimally and that reliable data is generated that you can build on. 18

TRAINING Services – Training ENGINEERS MAINTENANCE PURCHASING/QM Learning together – successful together With its wide range of online and classroom training courses, the FST Academy not only ensures that FST employees continue to develop their skills. It also offers a customized training program for custom- ers, suppliers and interested parties. Would you like to gain basic knowledge or deepen your un- derstanding of materials, design, and how seals function in various applications? Whether you are a beginner or a budding expert, you will find the right seminar here – tailored to your requirements and role. Self-paced online learning with the help of webinars as well as practice-oriented classroom training are systematically sequenced for an optimal learning process in theory and practice. Besides basic semi- nars, the range is rounded off by thematic master seminars and expert forums on trend-setting technologies and innovations. Discover the current training program of the FST Academy. Simply register for the training portal and sign up for your desired seminar. Freudenberg Sealing Technologies experts also regularly visit partners and customers. At so-called TechDays, they impart product knowledge on site and help solve problems. FST Academy VORTEILE IM ÜBERBLICK BENEFITS AT A GLANCE y Vorteil 1 y First-hand expertise y y Independent online learning y y Virtual training y Special seminars y Expert forums y Also on site & N O I T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 19 X E D N I

Services – LC Freudenberg Xpress® Customized Solutions LC FREUDENBERG XPRESS® CUSTOMIZED SOLUTIONS As a result, Freudenberg Xpress® develops its port- folio beyond CNC machined seal and part services by providing complementary CNC semi-finished products, tools, as well as CNC software and retrofit services. The service landscape is further comple- mented by the LC’s customized solutions service which supports its customers via highly custom- ized rubber-molded and rubber-metal parts. MACHINED SEALS Our state-of-the-art CNC production capabilities make the machining of original designs possible. A drawing, a sample or simply a discussion with our experts is usually all that is needed to develop your customized seal. In terms of quality, we offer original Freudenberg materials as well as industrial standard materials – manufactured and delivered in the shortest time frame. ENGINEERS MAINTENANCE PURCHASING/QM Freudenberg Xpress® becomes Lead Center Freudenberg Xpress® Customized Solutions Traditionally, the Lead Center (LC) Freudenberg Xpress® with its ad hoc CNC services is known for cus- tomer-specific sealing solutions in original Freuden- berg quality. Due to its global footprint and proxim- ity to its customers speed has always been essential. With the acquisition of the Trygonal Group in 2024, Freudenberg Xpress® further expanded its service capabilities becoming the first Industry Service Lead Center within Freudenberg Sealing Technologies. Freudenberg Xpress® Customized Solutions MACHINED SEALS & PARTS y MR O – Maintenance, Repair, and Overhaul y Prototyping y High-Precision y Small Series y Splicing & Welding CUSTOMIZED SOLUTIONS y Rubber-molded Parts y Rubber-metal Parts SEALING UTILITIES y CNC Billets (Components) y CNC Software & Machine Retrofit y CNC Tools Freudenberg Material Competence Compounds Freudenberg Sealing Competence Product Designs 20

Services – LC Freudenberg Xpress® Customized Solutions MRO – Maintenance, Repair, and Overhaul In case of urgent de- mands, we produce and deliver your parts within 24 hours – in original quality and design. The base for that is our global network and the resulting proximity to customers around the world. Prototyping We see the relationship to our customers as a part- nership. That is why we support them to validate their own sealing needs and come up with quick prototypes in original ma- terial quality. High-Precision Our innovative manufac- turing possibilities enable the smallest tolerance bands, whenever other production processes are no longer suitable. Small Series With our small series service, we provide our customers the most cost- efficient sealing and plastic part solutions. A time- consuming and costly tooling production is not necessary. Splicing & Welding With our splicing and welding technology, there are no limits in terms of seal size. Outstanding technical features are achieved throughout the whole seal. SEGMENTS AT A GLANCE y Distribution y Semiconductor y Hydropower y Oil & Gas y Food & Beverage y Pharmaceutical y Chemical y Other Energy & N O I T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 21 X E D N I

Services – LC Freudenberg Xpress® Customized Solutions CUSTOMIZED SOLUTIONS The customized solutions service supports our customers beyond the traditional boundaries of CNC machined seals and parts. It adds rubber-met- al parts, foam products as well as rubber parts or seals in different materials. Rubber Parts Whether your application requires a very large seal, extremely low tolerance bands, or customer-spe- cific solutions in smaller lot sizes – starting from lot-size 1 – our rubber part service is the solution. With the help of a variety of production tech- nologies, we can process and offer anything from industrial standard rubber to materials withstand- ing extreme conditions – in customer-specific dimensions. We can react in the shortest time to any customer-specific seal demand. Rubber-Metal Parts Being able to machine and process any kind of metal in-house, we can offer any kind of rubber- metal part. Starting from rather simple seals requir- ing a metal carrier to sup- port the product in the installation space up to highly-complex rubber-metal combinations re- quiring the bonding of highly demanding metal, thermoplastic, and/or elastomeric compounds. Our vertical integration and broad production portfolio pushes the boundaries of what is possi- ble even further. Foamed Products Whether it is a light yet ultra- stable special foam, a casting component with excellent mechanical properties, or a particularly tough integral foam, we can develop the right solution for you with our polyurethane foam product service. SEALING UTILITIES We support our customers not only with finished sealing products, but also with various products and services in the area of CNC production. This includes semi-finished products, CNC software, machine retrofit or CNC tools. CNC Billets (Components) We produce semi-finished products made for your own CNC production in sizes up to 2.1 metres in over 50 different materi- als. With more than 600 dimensions per material as well as industry-specific certificates (e.g. FDA, 3-A Sanitary Standards or EU (Reg.) 1935/2004), our extensive CNC semi- finished product portfolio provides the right solution for nearly every appli- cation. If specific requirements are needed, we also have the possibilities to develop a customer- specific compound for your individual application. CNC Software & Machine Retrofit We offer state-of-the-art CNC machines specifically tailored to your individual needs. During the respec- tive retrofit service, our experts offer extensive on-site consultation. Whether you need high automation, a high diam- eter range, or the most cost-efficient production equipment – we have the right solution. 22

Services – LC Freudenberg Xpress® Customized Solutions CNC Tools We stock indexable inserts, carbide knives, blades, holders and VD I holders from all well-known man- ufacturers made from the best These high-quality products are tailored to your individual machine system. steels. WORLDWIDE NETWORK A global network of local manufacturing partners and own production sites enables proximity to our customers. Expert advice on site and an extensive local service portfolio make us the right partner. & N O I T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P Discover the Find out more in Explore the website! the brochure! production in the virtual tour! S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B FST Locations Partner locations S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 23 X E D N I

Online tools as a digital aid Freudenberg Sealing Technologies offers a wide range of online tools to make your daily work in the sealing business easier. Whether you use the product catalog and ordering platform to order your new seals or the FST configurators to find the right seal first, the online tools make it a breeze. Services – Online Tools ONLINE TOOLS ENGINEERS MAINTENANCE PURCHASING/QM PRODUCT CATALOG The FST product catalog provides an overview of the portfolio D o you need a Simmerring®, an O-ring or another seal? Whether you are looking for a Freudenberg premium seal or a Dichtomatik seal that meets common industry standards, you will find the right seal here. Explore the possibilities of the product catalog or contact the person you normally deal with if you are looking for an individual sealing solution. ORDERING PLATFORM EASY Order gaskets in the blink of an eye On the EASY ordering platform, you can quickly and easily find and order the seals you need and receive your specific prices and availability in real time. EASY gives you access to a uniquely large portfolio of over 130,000 products from the Freudenberg and Dichtomatik brands. With the EASY Business Connector, FST provides a powerful interface to which all common enterprise resource planning systems can be connected. EBC is thus a real alternative to EDI. 24 24

Services – Online Tools SIMMERRING® SELECTOR Are you looking for a Simmerring® suited for your field of application? With the help of the Simmerring® selector, you can quickly and easily find the right Simmerring® for your application by entering specific application parameters in just a few steps. O-RING CONFIGURATOR Are you looking for an O-ring and the correspond- ing installation space? FST’s innovative, web-based O-ring configurator sets improved standards as an auxiliary application for O-ring selection. The goal of this online tool is to select an optimal combination of O-ring and in- stallation space to ensure a reliable seal. Unlike other O-ring configuration programs, the calcula- tion analyses and target value recommendations are based on the current ISO 3601 and other inter- national O-ring standards. HYDRAULIC SELECTOR Are you in need for sealing solutions of your hy- draulic cylinder? Find the right seal for new designs or replacement seals in just a few clicks! The online application offers you the right sealing solution for your tech- nical requirements and installation space. The selector is connected to our EASY ordering platform to enable quick ordering. & N O I T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 25 X E D N I

Services – Online Tools ACCUMULATOR SELECTOR Our innovative Accumulator Selector simplifies the process of finding the right recommendations for an accumulator. With the selector, you can optimize your workflow and receive tailored solu- tions for your specific requirements. CHEMICAL RESISTANCE GUIDE Get exclusive access to the results of decades of testing and experience. The Chemical Resistance Guide shows you the appropriate sealing materi- als for the common process media used in gener- al industry and process industries, such as acids and sulfates, and helps you optimize your process- es and maximize seal life in the field. CIP/SIP GUIDE Determine the right cleaning agents for your pro- cess based on the Freudenberg materials you use. Or vice versa: find the right seal materials for your cleaning process. 26

CAD DOWNLOADS Use the two- and three-dimensional CAD geome- tries and model drawing sketches of tens of thou- sands of sealing components. These are available to you in a variety of ﬁle formats. The CAD service from Freudenberg Sealing Technologies makes it easier for you to design your components. Why com- plicate things when they can be so simple? 3D ANIMATIONS Discover the innovative sealing solutions for appli- cations in various market segments with the 3D an- imations from Freudenberg Sealing Technologies. Services – Online Tools & N O I T C U D O R T N I S E C I V R E S D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A S C I L U A R D Y H S C I T A M U E N P R E W O P D U L F I R E W O P D U L F I – S N O T A C I I L P P A – S N O T A C I I L P P A S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P X E D N I 27

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I M A T E R A L S A N D P R O C E S S E N G N E E R N G I I 2 9 INDEX STUFFING BOX PACKINGS DIAPHRAGMS BOOTS & BELLOWS HYDRAULIC ACCUMULATORS SPECIAL SEALING PRODUCTS STATIC SEALS FLUID POWER APPLICATIONS – PNEUMATICS FLUID POWER APPLICATIONS – HYDRAULICS SEALS FOR ROTARY APPLICATIONS M a t e r i a l s a n d p r o c e s s e n g n e e r i n g i INTRODUCTION & SERVICES MATERIALS AND PROCESS ENGINEERING

Materials and Process Engineering TABLE OF CONTENTS 1. HISTORY INTRODUCTION TO THE WORLD OF POLYMERS 2.1 Function of a seal 2.2 Polymer materials 2.3 Material abbreviations GENERAL MATERIAL SELECTION AND DESCRIPTIONS 3.1 Material selection 3.2 Material descriptions 3.3 All-purpose Rubbers NR – IR BR SBR 3.4 Speciality Rubbers IIR EPDM CR CSM NBR XNBR AU – EU ECO ACM AEM EVM FKM FFKM HNBR VMQ – FVMQ 3.5 Thermoplastic Elastomers (TPE) TPE-O TPE-V TPE-S TPE-U TPE-E TPE-A 3.6 Technical Thermoplastics PO POM PK PA PBT 2. 3. 30 34 36 36 36 44 48 48 48 50 50 52 53 54 54 55 56 57 58 60 61 62 63 64 65 66 68 69 70 72 72 73 74 75 76 77 78 78 80 81 82 84

3.7 High-Performance Thermoplastics PPS PPA PEI PEEK ETFE / PVDF PFA / FEP PTFE PAI 3.8 Duromers UF UP EP PF PI Composition of FST material designations 3.9 3.10 Variety of materials 4. UNDERSTANDING ELASTOMER FORMULATIONS 4.1 Formulation ingredients Rubber Fillers Plasticizers Processing aids Anti-Ageing agents Cross-linking system Additional additives 5. 5. CROSS-LINKING CHEMISTRY Cross-linking density Cross-linking characteristics Optimization of elastomer processing Compatibility of the cross-linking chemicals Cross-linking agents Cross-linking with Sulfur Cross-linking with Peroxides Tempering 5.1 5.2 6. CARRIER PARTS Design of the composite component Pretreatment of the carrier parts Production of the elastomer composite component Table of contents 85 85 86 88 89 90 92 94 96 97 98 99 100 101 102 103 103 104 104 105 105 107 109 109 111 113 114 114 115 117 117 117 118 120 121 123 124 124 125 I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 31 X E D N I

Materials and Process Engineering 7. 7. FROM RAW MATERIAL TO FINISHED PART 7.1 Procedure 7.2 7.3 Mixture production Shaping and vulcanization Choice of shaping procedure Influence of the rubber compound Tool competence Overview of the shaping process Compression Molding Transfer Molding Injection Molding Cold runner technology Choice of procedure Extrusion process Roller-head System (Press) sintering of PTFE Plastic processing 7.4 7.5 8. TESTING METHODS Processing characteristics Static-mechanical properties Compression set Temperature-frequency behavior Influence of media: Storage tests Heat resistance, aging behavior Chemo-stress relaxation Service life 9. DAMAGE ANALYSIS 9.1 9.2 Damage analysis process Typical damage phenomena, causes and mechanisms Material defects Manufacturing errors Design error Mechanical stress Thermal stress Explosive decompression Climatic stress 10. DEFECT CHECKS 32 126 126 126 130 130 132 132 133 133 133 134 135 135 136 138 139 141 143 144 147 151 152 154 156 157 158 163 163 166 166 167 170 170 172 173 174 177

11. PROPER STORAGE Storage conditions Suggestions for the assessment of elastomer components after the initial storage period 12. CHEMICAL RESISTANCE 13. SUMMARY OF THE STANDARDS MENTIONED 14. EXCURSUS: COMMON TERMINOLOGY IN THE RUBBER INDUSTRY Table of contents 178 178 179 180 213 216 I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 33 X E D N I

Materials and Process Engineering 1. HISTORY A LONG HISTORY Rubber is a fascinating material with a long and varied history. Natural rubber has been used for thousands of years; the oldest known items made of rubber come from Central America and are over 3,500 years old. Natural rubber appears again and again in historical accounts. There are reports of children in the Amazon region playing with a small, bouncy, rubber- like ball, and indigenous peoples who had waterproof raincoats. Rubber is mentioned in Europe for the first time in the 16th century, and this was followed by the invention of the eraser and the impres- sive demonstration by physics professor Jacques Alexandre Cesar Charles, who was able to seal a balloon filled with hydrogen with the help of latex milk in 1783. Groundbreaking discovery Despite all these early uses of latex milk, the real success story only began with the groundbreaking discovery of Charles Nelson Goodyear. Goodyear was a tinkerer and inventor and experimented with natural rubber for many years. He wanted to de- velop a non-sticky, odorless and temper- ature-resistant impregnation for fabrics, which he surprisingly succeeded in doing in 1839. There are various stories about exactly how his discovery came about. One tells how he hid the last of the rubber-sulphur mixture from his wife in his hot oven. When he looked at the mixture again the next morning, he realized that it had changed significantly: from soft and sticky to dry and elastic. Since the transformation of plastic natural rubber into elastic rubber was achieved with the help of sulphur and heat, he named the process "vulcanization," after the Roman god of fire, Vulcan. Unfortunately, Goodyear was not a clever businessman, so despite his revolutionary invention, which even earned him an invi- tation to the first World's Fair in London in 1851, he was never commercially success- ful and died impoverished at the age of 59. Temporary monopoly With the commercialization of the pneu- matic tire by John Boyd Dunlop in the late 19th century, the demand for natural rubber exploded. Rubber trees (Hevea brasiliensis), from whose bark the latex sap is extracted, were mainly native to the Amazon basin, and Brazil was very protective of its economic supremacy. The export of seeds or plants was strictly forbidden – it was punishable by death. Nevertheless, the Englishman Henry Wickham managed to smuggle germinable seeds to England in 1876. This broke Brazil's monopoly and around the turn of the century, the first rubber plantations were established in Ceylon and other English colonies in the tropical and subtropical climates of Southeast Asia. Even today, the majority of natural rubber comes from this region. The former world market leader Brazil has completely lost its economic importance, not least due to a fungus that makes the plantation cultivation of rubber trees in South America largely un- profitable today. The era of synthetic rubber The demand for natural rubber also rose sharply when the wave of motorization began in Europe at the beginning of the 20th century and significantly more tires were needed. 34

1. History The first patent for synthetically pro- duced rubber was granted in 1909: Fritz Hofmann had invented methyl rubber. At the end of the 1920s, an industrial process made it possible to produce styrene- butadiene rubber (SBR) for the first time. The first fully synthetic rubber was in- vented by Ivan Kondakov in 1901. Two other synthetic rubbers were also devel- oped at this time: nitrile rubber (NBR) and chloroprene rubber (CR). Today, the rubber industry uses around 25 classes of synthetic rubber in addition to natural rubber, which still accounts for around 40% of the rubber used worldwide. Exciting future The history of rubber is extraordinary and the triumph of this elastic material con- tinues unabated. Whether hoses or baby pacifiers, shoe soles or V-belts, seals or conveyor belts, tires, vibration dampers or baking tins: the portfolio of rubber products has never been as diverse as it is today. In addition to the ongoing specialization of elastic materials, careful handling is becoming increasingly important. This applies both to the raw materials and their processing as well as to the disposal and recycling of the products. New challenges are currently arising from changes to chemicals legislation and in- creased volatility in supply chains. There is also an increasing focus on legislation and the desire of a growing number of customers for more sustainable solutions and meaningful sustainability reporting. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 35 X E D N I

Materials and Process Engineering 2. INTRODUCTION TO THE WORLD OF POLYMERS 2.1 FUNCTION OF A SEAL GENERAL SEALING EFFECT Surfaces are never smooth; every surface has microscopic imperfections. Surface treatments such as grinding or polishing can reduce the roughness, but this is not enough to seal against liquids or gases. What is needed is a material that adapts so well to the surface roughness that it largely compensates for it and thus clos- es leakage paths. This completely sepa- rates the installation spaces on both sides of a seal. Rubber is by far the first choice here: elastomers have the necessary flexibility to adapt to the surfaces of the compo- nents and at the same time the rigidity to remain dimensionally stable. CLASSIFICATION OF SEALING PRINCIPLES Sealing applications can be divided into two categories: Static seals are used to seal two station- ary components together. Typical appli- cations are seals for closures or flanges – the O-ring is one of the most common static seals. Surface roughness does not create a sealing effect A seal compensates for surface roughness and seals it off Fig. 1 General sealing effect of gaskets 36 Dynamic seals mutually seal two compo- nents that move relative to each other. Depending on the type of movement, a distinction is made between rotary seals (shaft seals) and translatory seals (e.g. piston or rod seals). A distinction is also made between con- tact and non-contact seals. The latter are largely friction-, abrasion- and heat-free, but at the cost of higher leakage rates. The sealing mechanisms of the two categories differ fundamentally and are explained in more detail in the respective chapters of this manual. 2.2 POLYMER MATERIALS Polymer material is a collective term for materials that consist of very large, mostly chain-like molecules, called macromole- cules or polymers. Natural representatives of this class of materials are animal and plant fibers such as silk, wool, cotton or cel- lulose; substances such as starch or gelatin and natural rubber are also natural poly- mers. However, the majority of polymers in use today are produced synthetically (artificially → "plastics"). Low molecular weight building blocks combine in the polymerization reaction to form long polymer chains with molecular weights between 10,000 and 10 million g/mol. Polymers that consist of only one type of monomer are called homopolymers; if they are made from two or more different monomers, they are called copolymers. PROPERTIES Unlike low-molecular substances, polymers do not usually crystallize when a liquid polymer melt cools, but are amorphous

2. Introduction to the world of polymers I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I at rest moving Seals R O F S L A E S Y R A T O R S N O T A C I I L P P A Static seals Dynamic seals rotating moving linear moving Contact Non-contact Shaft seals Rod, piston and linear-guided seals R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P Venting O-ring Bellows seal Profile seal Flat seal Membrane seal Fig. 2 Classification of seals (= non-crystalline) in the solid aggregate state. The arrangement of the polymer chains in the amorphous solid does not follow any rules, the polymer chains are tangled up, a bit like a molecular pile of spaghetti. Polymers with a particularly regular molecular chain structure can crystallize, but never completely, only in sections along the chain; they are partial- ly crystalline. For crystalline solids, the phase transition from solid to liquid is called melting. The reverse process during cooling is called crystallization. In the case of amorphous materials, these processes are referred to as softening and solidification, respectively. The associated phase transition is called the glass transi- tion point. The chemical and thermal resist- ance of polymer materials is also largely Contact Non-contact Contact Stuffing box Mechanical seal Radial shaft seal Gap seal Labyrinth seal Grooved ring Wiper Compact seal S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P determined by the structure of the polymer chains. For example, the main chain of a polymer can consist of carbon atoms strung together, but it can also contain other atoms such as oxygen, nitrogen or silicon. Additional atoms or molecular groups, the so-called side groups, are attached to the atoms of the main chain. These can be hydrogen, chlorine or fluorine atoms as well as alkyl, nitrile or ester groups and many more. amorphous semi-crystalline Fig. 3 Amorphous vs semi-crystalline C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 37 X E D N I

Materials and Process Engineering so great that the molecules of the liquid cannot penetrate the polymer. Non-polar substances There are only weak attractive forces be- tween the molecules of non-polar sub- stances, the Van der Waals forces. These are based on induced dipoles. Non-polar substances are only dissolved by non-polar media. Examples of non-polar media in- clude classic fuels or mineral oils. Polar substances The stronger dipole forces act between the molecules of polar substances. In contrast to the Van der Waals forces, these are based on permanent dipoles. Polar polymers can only be swollen or dissolved by polar media. Water, alcohols, glycols and ester oils are examples of polar media. The temperature resistance of the polymer results from the stability of the chemical bonds of the polymer molecule: a car- bon-carbon (C-C) double bond is less stable than the corresponding single bond, a car- bon-fluorine bond is more stable than a carbon-chlorine bond. C-C double bonds are an easy target for ox- ygen and especially ozone, so that polymers with many double bonds in the main chain cannot withstand high temperatures or ag- gressive media. Saturated polymers with- out double bonds are generally more resist- ant to ageing. To assess the resistance of polymer mate- rials to liquids or gases, it helps to compare the polarities of the two substances. If the polymer and liquid are chemically very sim- ilar, the liquid will interact strongly with the polymer, i.e. penetrate its structure and cause it to swell, or dissolve completely. "Similia similibus solvuntur," or "similar things dissolve in similar things," is one of the basic principles of chemistry. If the polarities of the liquid and polymer are very different, the dissolution process is prevented: The forces between the indi- vidual molecules of the liquid and the indi- vidual molecules of the polymer are then NR NBR Fig. 4 Natural rubber: NR: non-polar – only C and H; nitrile rubber: NBR: polar due to the nitrile group CN 38

2. Introduction to the world of polymers PI PAI TPI PES PEI PPSU PSU PEKK PEEK PTFE LCP PPS PA46 PPA I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P e High Performance Polymers c n a m r o f r e p d n a e c i r P Engineering Polymers PC PMMA PPE PBT PET PA66 PA6 POM PK Commodity Polymers ABS PVC PS SAN PE PP amorphous semi-crystalline Fig. 5 Material pyramid of thermoplastics S L A E S C I T A T S Elevated temperatures promote interac- tion and thus swelling or dissolution. The contact with a liquid often also causes the exchange of certain components of the medium and the polymer material, such as plasticizer oils or anti-ageing agents. This does not necessarily change the volume, but important constituents migrate from the polymer matrix into the surrounding medium, which significantly changes the properties and contaminates the medium itself with the extracted substances. POLYMER CLASSES Polymer materials are usually divided into four classes, which differ significantly in the temperature curve of their stiffness (their modulus) (see also → Material over- view table, page 44). Thermoplastics Thermoplastics are the largest of the four polymer classes in terms of volume. They consist of linear or branched molecular chains. The spatial order of the molecular struc- ture determines whether a thermoplastic is amorphous or semi-crystalline. The crys- tallinity has a considerable influence on the mechanical properties and processing behavior. For example, it determines how hard, ductile, brittle or tough a material is. Thermoplastic materials soften or melt at high temperatures and thus become plastically deformable. Even before the phase transformation point is reached, the tendency to creep under load increas- es significantly. Most thermoplastics are soluble in suitable solvents. Thermoplastics are divided into three class- es: standard thermoplastics, engineering thermoplastics and high-performance thermoplastics and are often shown as a material pyramid as in → Fig. 5. G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 39 X E D N I

Materials and Process Engineering Standard thermoplastics are inexpensive bulk plastics with moderate mechanical properties and temperature resistance not significantly above +100 °C. They are mainly used in the packaging and con- struction industries. They are mainly used in the packaging and construction industries and account for around 80% of the global volume of plastics. Engineering thermoplastics have better mechanical properties and are therefore suited for more demanding technical applications that require higher stiffness and strength or higher temperature or chemical resistance. High-performance thermoplastics, also known as high-performance polymers (HPP), are materials that are used for spe- cial applications and account for signifi- cantly less than 1% of the annual volume of plastics. Their continuous service tem- peratures are above +150 °C, they have high ageing and dimensional stability, cou- pled with high chemical resistance and often outstanding mechanical properties. External applied force leads to a state of higher order At rest Fig. 6 Entropy elasticity 40 Elastomers Elastomers consist of a special type of poly- mer called rubber. Rubbers are generally amorphous and have a low glass transition point of well below 0 °C. Through chemical reaction with suitable cross- linking chem- icals, the individual polymer chains are linked during vulcanization to form a wide- meshed three- dimensional network. This is how elastic rubber is created from rubber that is plastically deformable under heat. Due to the chemical bonding of the rubber chains with each other, elastomers can neither melt nor dissolve, but they swell strongly if the rubber and liquid have the same polarity. The reason for the elasticity of rubber can be found in its molecular structure: The effect of an external force forces the tan- gled polymer chains to align themselves from their state of equilibrium in the direction of the force. This ordering of the macromolecules costs energy, as it is accompanied by a reduction in disorder, or entropy. The chemical cross-linking of the polymer chains in the rubber prevents the chain segments from sliding irrevers- ibly against each other. Once the load has been relieved, the macromolecules seek to return to their (disorderly), energetically more favorable state of equilibrium. The deformation occurs spontaneously as soon as the force is no longer applied. The driving force behind the elastic be- havior of rubber is therefore entropy minimization. This type of elasticity is therefore called entropy elasticity or rubber elasticity. Entropy-elastic behavior is observed in large strains up to several hundred percent.

2. Introduction to the world of polymers Elastomers only behave entropy-elastically above their glass point, below this they are leathery or hard like glass, and often brittle. Rubbers are divided into tire rubbers and special rubbers based on their main ap- plication. Typical elastomer applications in everyday life are rubber bands, balloons and tires, but also all kinds of seals, baby pacifiers and gloves. Duromers Like elastomers, duromers are chemically cross-linked polymers, however the degree of cross-linking is significantly higher, so that a close-meshed network is created after the cross-linking reaction and the molecular chains cannot move against each other. The mechanical properties of duromers are only slightly dependent on temperature. They often have no glass point and undergo a direct decomposi- tion reaction above a certain tempera- ture without softening significantly be- forehand. Duromers are very resistant in contact with solvents: they are insoluble and do not swell. Duromers are characterized by a very low creep tendency and high strength. They are generally very abrasion-resistant and per- meation-tight. Their coefficient of thermal expansion is in the range of common metals such as steel and aluminum and is adjustable to a certain extent. Disadvan- tages of duromers are their usually very low elasticity and lower load-bearing capacity under tension than under compression. Sockets, cladding and casings are often made of duromers, and many adhesives and paints belong to this material class. Due to the weight savings and adjustable thermal expansion, duromer materials are increasingly being used as metal substitutes. More and more frequently, duromers can also be found in sealing applications. Thermoplastic elastomers Thermoplastic elastomers (TPE) are multi- phase systems and consist of solid hard phases and elastic soft phases. The hard phases are physical cross-linking points that disengage at high temperatures. TPE materials combine the properties of thermoplastics and elastomers in that they are plastically deformable under heat and behave elastically at service temperature. The soft phase is responsible for the elas- tic behavior and low-temperature flexi- bility, while the hard phase determines the strength and heat resistance of the material. The service temperature lies between the glass transition point of the soft segment and the glass transition point or melting point of the hard segment. Block copolymer Elastomer alloy Elastic segment Thermoplastic segment Elastomer Thermoplastic Fig. 7 Sketch of two TPE classes I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 41 X E D N I

Materials and Process Engineering TPE Block copolymers Elastomer alloys Types of styrenes (TPE-S) Thermoplastic Polyolefins Polyether esters (TPE-E) (partially) cross-linked (TPE-V) Polyurethanes (TPE-U) non-cross-linked (TPE-O) Polyetheramides (TPE-A) Fig. 8 Classification of TPE materials Other thermoplastic vulcanizates (MPR *, EA **) * Melt Processable Rubber ** Elastomeric Alloys When the temperature is increased, the material becomes flowable due to the melting of the hard phase and can be pro- cessed thermoplastically. After the material has cooled and solidified, the physical cross-linking points form again, so that the TPE material regains its original mechanical properties and is therefore also recyclable. Due to the physical cross-linking, the material prop- erties of TPE are not only determined by their composition, but also to a large extent by their morphological structure. Hard and soft phases can be produced in the same molecule in the form of different molecular segments, but also as a mixture of elastomers in thermoplastics. As out- lined in → Fig. 8, TPE materials are divid- ed into two classes: block copolymers and elastomer alloys (also known as polymer blends or elastomeric alloys). The polymer chains of block copolymers consist of two different monomers. One chain segment (block) is amorphous and has a low glass transition point; these chain segments are flexible at service temperature. The other segment has a high glass transition point or is partially crystalline with a melting point well above the service temperature; these chain segments are rigid. Due to their incompatibility, the segments demelt; hard domains form in a flexible matrix. If the temperature is below the glass transition or melting point of the hard domains, the material behaves entropy- elastically; above this, the block copolymer melts. 42

2. Introduction to the world of polymers Elastomer alloys are mixtures of thermo- plastics and non-cross-linked rubber or cross-linked elastomer. When producing these mixtures, it must be ensured that the rigid thermoplastic phase forms the continuous phase (matrix); the flexible rubber phase is dispersed in it in the form of small flexible beads. The smaller the elastomer beads are, the better the prop- erties of the alloy are. High-quality soft-touch handles and buttons are often made of TPEs. TPEs are also used as mold and profile seals, as cable grommets, in children's toys and, due to their purity, in a wide range of medical and food technology applications. → Fig. 9 shows the modulus of elasticity as a function of temperature for the four polymer classes. Here too, the following applies: below the glass transition or melting temperature of the hard domain, the TPE behaves elas- tically; above this temperature, it softens and can be molded using standard thermo plastic processing methods. Thermoplastic Thermoplastic elastomer Elastomer Duromer l s u u d o m E - l s u u d o m E - l s u u d o m E - l s u u d o m E - Temperature Temperature Temperature Temperature = Service range = Cross-linking points Fig. 9 Schematic structure and temperature behavior of individual plastics I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 43 X E D N I

Materials and Process Engineering 2.3 MATERIAL ABBREVIATIONS OVERVIEW There are common abbreviations for all polymers that make it easier to deal with the often unwieldy material designations; they are defined in internationally valid material standards. Thermoplastics and duromers are usually named according to the abbreviations listed in DIN 7728-1, ISO 1043.1 or ASTM D 1600. For rubbers, the standards ASTM D 1418 and the largely identical ISO 1629 list the abbreviations. Rubbers are subdivided into various groups based on the structure of the main chain. The abbreviations for thermoplastic elastomers (TPE) can be found in DIN EN ISO 18064. The following table summarizes the ma- terial abbreviations of the most relevant sealing materials. The polarities of the polymers have been roughly categorized to provide an initial indication of chemical compatibility. More detailed information on the resistance of the most important rubbers can be found in → “12. Chemical resistance”, page 180. BRIEF DESCRIPTION CHEMICAL DESIGNATION OF THE BASE POLYMERS non- polar semi- polar polar ELASTOMERS BRIEF DESIGNATION ACCORDING TO ASTM D 1418/ISO 1629 R group: unsaturated hydrocarbons NR IR BR SBR IIR CIIR BIIR CR NBR X X X X X Natural rubber Isoprene rubber Butadiene rubber Styrene-butadiene rubber Butyl rubber Chlorobutyl rubber Bromobutyl rubber Chloroprene rubber Nitrile rubber X X X X Tab. 1 Designations and polarities of the most common polymers 44

2. Introduction to the world of polymers BRIEF DESCRIPTION CHEMICAL DESIGNATION OF THE BASE POLYMERS non- polar semi- polar polar R group: unsaturated hydrocarbons XNBR HNBR XHNBR carboxylated nitrile rubber Hydrogenated nitrile rubber Carboxylated hydrogenated nitrile rubber M group: saturated hydrocarbons EPM EPDM CM CSM EVM ACM AEM FKM FEPM FFKM Ethylene-propylene rubber Ethylene propylene diene rubber Chlorinated polyethylene X X Chlorosulfonated polyethylene Ethylene-vinyl acetate rubber Acrylic rubber Ethylene acrylate rubber Fluororubber Tetrafluoroethylene propylene rubber Perfluoro rubber Q-group: Silicon in the main chain MQ VMQ PVMQ FVMQ Silicone rubber Silicone rubber Phenyl silicone rubber Fluorosilicone rubber X X X X X X X X X X X X X X X I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 45 X E D N I

Materials and Process Engineering BRIEF DESCRIPTION CHEMICAL DESIGNATION OF THE BASE POLYMERS non- polar semi- polar polar O group: oxygen in the main chain CO ECO Epichlorohydrin rubber Ethylene oxide- epichlorohydrin rubber U group: carbon, oxygen and nitrogen in the main chain AU EU Polyester urethane rubber Polyether urethane rubber THERMOPLASTICS BRIEF DESIGNATION ACCORDING TO DIN 7728-1, ISO 1043.1, ASTM D 1600 PE PP POM PK PBT PA PPA PPS PEI PEEK PAI ETFE PVDF X X Polyethylene Polypropylene Polyoxymethylene Polyketone Polybutylene terephthalate Polyamide Aromatic polyamide Polyphenylene sulfide X Polyetherimide Polyetheretherketone Polyamideimide Ethylene-tetrafluoro- ethylene copolymer Polyvinylidene fluoride X X X X X Tab. 1 Designations and polarities of the most common polymers 46 X X X X X X X X X

2. Introduction to the world of polymers BRIEF DESCRIPTION CHEMICAL DESIGNATION OF THE BASE POLYMERS non- polar semi- polar polar THERMOPLASTICS BRIEF DESIGNATION ACCORDING TO DIN 7728-1, ISO 1043.1, ASTM D 1600 PFA FEP PTFE Perfluoroalkoxy copolymer Fluorinated ethylene- propylene copolymer Polytetrafluoroethylene THERMOPLASTIC ELASTOMERS ABBREVIATION ACCORDING TO DIN EN ISO 18064 Block copolymers TPS TPU TPC TPA Blends TPO TPV Thermoplastic styrene block copolymers Thermoplastic polyurethane Thermoplastic copolyester elastomers Thermoplastic polyamide elastomers Olefin-based thermoplastic elastomers Thermoplastic vulcanizates X X X X X X DUROMERS BRIEF DESIGNATION ACCORDING TO DIN ISO 1043.1/ASTM D 1600 UF PF UP EP PI Urea-formaldehyde resin Phenol-formaldehyde resin Unsaturated polyester Epoxy resin Polyimide X X X X X X X X I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P ASTM = American Society for Testing and Materials; ISO = International Organization for Standardization; DIN = Deutsches Institut für Normung e.V. 47 X E D N I

Materials and Process Engineering 3. GENERAL MATERIAL SELECTION AND DESCRIPTIONS intended to be a substitute for a materials science book. The selection of represent- ative thermoplastics, TPEs and duromers has been limited to those materials that are relevant for sealing technology. 3.1 MATERIAL SELECTION Selecting the best suited polymer material for a specific sealing application is a key task in material development. It requires in-depth knowledge of the specific prop- erties of polymers and the possibilities of tailoring materials to the application through compounding. A good technical understanding of the seal, its exact installation situation and the load spectrum of operating temper- ature, media contact and mechanical load is also important. Special requirements such as flame behavior or wear protection must also be taken into account. Ultimately, seal development can only succeed if the material, manufacturing process and seal design work together successfully. 3.2 MATERIAL DESCRIPTIONS The following table lists the basic prop- erties of the most important elastomer classes and the typical areas of applica- tion. It should be noted once again that such categorizations are always somewhat imprecise and do not take into account the sometimes considerable ranges within a rubber class. The properties of an elastomeric material can also be varied within certain limits through the clever use of fillers, anti-ageing agents and co- ordinated cross-linking systems. The most important polymer materials are explained below; of course, this level of detail also has its limits and is not Resistance Guide 48

I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P ‒40 / +140 D D + − +++ D +++ +++ +++ D VMQ ‒60 / +200 + D +++ −− −− +++ D +++ − B + + + +++ Oil and fuel hoses, rollers Cables, films, hoses, seals FVMQ ‒80 / +175 B D +++ −− D +++ +++ +++ +++ B +++ +++ Aviation, fuel and turbocharger hoses, diaphragms, seals SBR ‒50 / +100 FKM ‒25 / +200 HNBR ‒40 / +150 NBR ‒40 / +100 + + + + + + + D +++ B D + + + + −− + −− −− − −− D Tires, conveyor belts +++ +++ +++ +++ +++ +++ +++ Aviation, turbocharger hoses, diaphragms, seals +++ +++ +++ +++ +++ −− +++ Toothed belts, rod and piston seals −− + −− +++ D −− D Automotive parts, fuel/oil hoses, for foodstuffs such as milk + + ++ CIIR, BIIR ‒40 / +120 −− D IIR ‒40 / +120 −− D −− +++ +++ D −− +++ +++ +++ + + + −− NR, IR ‒60 / +80 +++ +++ +++ +++ −− −− +++ −− −− ‒60 / +100 B +++ +++ +++ −− −− +++ −− −− + + − − +++ +++ −− + −− −− Inner tubes, inner liners, vibration dampers Inner tubes, inner liners, vibration dampers Tires, conveyor belts, highly elastic articles, high-performance tires, consumer goods for foodstuffs −− −− Tires, conveyor belts, dynamically highly stressed articles + + + + 3. General material selection and descriptions e c n a t s i s e r e r u t a r e p m e T e c n a t s i s e r l a c i m e h C e c n a t s i s e r e m a l F AREAS OF APPLICATION C ° e g n a r e r u t a r e p m e T t e s n o i s s e r p m o C h t g n e r t S e c n a t s i s e r n o i s a r b A e c n a t s i s e r r e h t a e W s s e n t h g i t s a G e c n a t s i s e r r e t a W e c n a t s i s e r e n o z O y t i l i b i x e l f d o C l e c n a t s i s e r l i o l a r e n M i ‒40 / +150 + + + D + +++ + +++ D D −− +++ Oil hoses, seals ‒25 / +150 − D D D D +++ −− + +++ D −− +++ Oil hoses, oil pan seals MATERIAL AEM ACM ECO BR CR ‒45 / +100 B EPDM ‒50 / +150 + +++ Excellent ++ Good/Outstanding + Good + + + + + + + + D + + D +++ + Tires, conveyor belts, dynamically highly stressed articles D +++ +++ +++ −− + −− +++ Automotive profiles, cooling water/ steam hoses, window seals, construction profiles B Sufficient/Good D Sufficient − Moderate/unsuitable − − Unsuitable Tab. 2 Basic properties and typical areas of application of the most important elastomer classes 49 X E D N I

Materials and Process Engineering 3.3 ALL-PURPOSE RUBBERS NR – IR NATURAL RUBBER is the only rubber of natural origin. The rubber tree produces the white latex sap primarily to protect against animal predation and to seal wounds – chemically speaking, it is an aqueous dispersion of small natural rubber droplets – high molecular weight cis-1,4-polyisoprene. Rubber trees only grow in a narrow belt around the equator – the largest producers are Thailand and Indonesia. Like any natural product, the quality of natural rubber can vary signif- icantly over the course of the year and from plantation to plantation. Today, technically specified NR grades guaran- tee consistent quality for sophisticated products. NR vulcanizates are characterized by a number of special features: NR can crystallize spontaneously or under strain. For this reason, NR vulcanizates achieve high mechanical strength even without the addition of reinforcing fillers and are self-reinforcing at high elongations. NR –60° 0° +80° +/- highly elastic – + low TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES They are highly elastic, extremely wear- resistant and exhibit good flexibility at low temperatures. This combination of properties makes natural rubber an important raw material for the tire industry, which requires around 70% of the world's NR volume, mostly in blends with other tire rubbers. NR is also used in the production of vibration con- trol components such as engine, machine and construction mounts, bushings and rubber-metal spring elements. Shoe soles and conveyor belts are also made of nat- ural rubber. There are also a number of products that are made directly from la- tex: These include disposable gloves, baby pacifiers, condoms and balloons. Cis-1,4-polyisoprene is also produced syn- thetically today. The synthetic ISOPRENE RUBBER IR differs in terms of some details from its natural “brother” NR and is also mainly used in the tire industry. 50

3. General material selection and descriptions PROPERTIES y thermal application range of –60 °C to +80 °C. When exposed to higher temperatures for longer periods, natural rubber can soften after pre- viously hardening y good media resistance in diluted acids and bases as well as in alcohols and glycol ether-based brake fluids y not resistant in mineral oils and greases, fuels and aliphatic, aromatic and chlorinated hydrocarbons y not very resistant to ozone and UV light y high strength even without rein- forcing fillers y highly elastic y resistant to abrasion and fatigue I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 51 X E D N I

Materials and Process Engineering BR –70° 0° 0° +85° +/- fatigue-resistant – + low TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES BR BUTADIENE RUBBER or cis-1,4-polybuta- diene is produced from the monomer butadiene. BR is characterized by high elasticity and abrasion resistance, and is very fatigue- resistant and therefore dynamically high- ly resilient. Its low glass transition temper- ature of below –100 °C ensures outstanding flexibility at low temperatures. As a pure hydrocarbon, it has the same chemical re- sistance as natural rubber. BR is difficult to process due to its low tack and is almost always used in blends with NR, IR or SBR. BR improves the fatigue re- sistance and low-temperature behavior of the blends and is mainly used in tires, es- pecially in the tread and sidewall, as well as in higher quantities in winter tires. BR is also used in vibration technology, V-belts, conveyor belts and shoe soles. The core of golf balls is made of BR. Buta- diene rubber is also used for impact mod- ification of brittle thermoplastics. PROPERTIES y thermal application range of –70 °C to +85 °C y good media resistance in dilute acids and bases, in alcohols and water y not resistant in mineral oils and greases, fuels, aliphatic, aromatic and chlorinated hydrocarbons y highly elastic y bending crack resistant y not very resistant to ozone and UV light y mainly used in blends with NR, IR, SBR 52

3. General material selection and descriptions I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I SBR –40° 0° R O F S L A E S Y R A T O R S N O T A C I I L P P A +100° +/- abrasion-resistant – + low + R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES O SBR STYRENE BUTADIENE RUBBER is a static copolymer comprised of butadiene and styrene. SBR rubbers are the most com- monly used synthetic rubbers in terms of volume. A distinction is made between emulsion and solution polymers, E-SBR and S-SBR (E = emulsion, S = solution) according to the two manufacturing processes. glass transition temperature of styrene. SBR vulcanizates are more resistant to abrasion than elastomers made from natural rubber, which is why SBR is mainly used for the production of tire treads. Many SBR rubbers are available in the form of standardized grades with uniform designations. Like NR, IR and BR, styrene butadiene rub- bers are typical tire rubbers. SBR vulcaniza- tes are characterized by a high reinforcing effect of filled grades, low hysteresis loss- es and thus low rolling resistance as well as high wet slip resistance due to the high Besides tires, materials made of SBR are preferred for the production of insulating mats, floor coverings, conveyor belts, con- struction profiles and sealing elements for hydraulic brakes. PROPERTIES y thermal application range of –40 °C to +100 °C y good media resistance in acids and bases as well as in alcohols and glycol ether-based brake fluids y unstable in mineral oils, greases, fuels and aliphatic, aromatic and chlorinated hydrocarbons y highly abrasion-resistant – better than NR y not very resistant to ozone and UV light y high reinforcing effect R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 53 X E D N I

Materials and Process Engineering 3.4 SPECIALITY RUBBERS IIR BUTYL RUBBER IIR – CIIR/BIIR –40° +130° 0° +/- low – + low TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY GAS PERMEABILITY IIR BUTYL RUBBER is a copolymer of isobuty- lene with a small proportion of isoprene. The halogenated rubbers CHLOROBUTYL RUBBER CIIR and BROMBUTYL RUBBER BIIR are obtained by a subsequent reaction with elemental chlorine or bromine. IIR vulcanizates have good resistance to weathering, ageing and ozone, which is due to the low proportion of double bonds in the main chain. The halogenated rubbers show slightly better setting behavior and slightly better heat and fatigue resistance. The gas and water vapor permeability of IIR vulcanizates is low. The media com- patibility is comparable to that of tire rubbers. Butyl rubber is used for insulating cable and sheathing, protective clothing and adhesives. The halogenated types are used to make tire tubes and the inner layers of tubeless tires. Halogenated butyl rubbers are also used for the heating bellows required for the vulcanization of tires, for pharmaceutical articles such as stoppers and closures and for mold seals. PROPERTIES y thermal application range –40 °C to +130 °C y good media resistance in glycol ether-based brake fluids, inorganic and organic acids and bases, hot water and steam up to +120 °C y unstable in mineral oils and greases, gasoline and aliphatic as well as aro- matic and chlorinated hydrocarbons y high damping y low gas permeability y bending crack resistant 54

3. General material selection and descriptions I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I EPDM –50° 150° 0° R O F S L A E S Y R A T O R S N O T A C I I L P P A +/- weather resistant – + low + R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY MECHANICAL PROPERTIES EPDM ETHYLENE-PROPYLENE-DIENE RUBBER is a copolymer of ethylene, propylene and up to 12% of a diene. The most common diene component is the ethylidene nor- bornene shown in the formula. EPD M rubbers with an ethylene content of over 60% can crystallize. The higher the ethylene content, the higher the strength and the lower the flexibility at low temperatures. Ethylene-propylene rubbers (EPM), i.e. copolymers without a diene component, are also widely used. EPD M vulcanizates are highly resistant to ozone, ageing and weathering ("outdoor materials") and therefore the material of choice for sealing profiles in the auto- motive and construction industries and for cable sheathing. Its good resistance to glycol makes it well suited for use in hoses and seals for brake fluids and cooling water. Due to their good resistance to hot water and steam, EPD M materials are used for water-bearing components and for prod- ucts that come in contact with drinking water and aqueous foodstuffs. EPM is used for oil additivation and impact modification of thermoplastics. PROPERTIES y thermal application range of –50 °C to +150 °C y good media resistance in hot water, steam, washing lyes, oxidizing media, acids, bases, polar organic media, ketones, glycol ether-based brake fluids y unstable in mineral oils and greases, gasoline and aliphatic as well as aro- matic and chlorinated hydrocarbons y weather-resistant R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 55 X E D N I

Materials and Process Engineering CR –30° +110° 0° +/- fatigue-resistant – + medium + Cl TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES Like NR, CR tends to crystallize, which is why unfilled vulcanizates also exhibit high strength. Chloroprene rubber is used in the adhe- sives industry. Surfing and diving suits are made of CR, as are many hoses, cables and profiles. Conveyor belts and drive belts are also made from CR. In sealing technology, CR vulcanizates are used for molded seals as well as for bellows and dust caps. CR CHLOROBUTADIENE RUBBER is a poly- merizate based on chloroprene (chloro- butadiene). CR elastomers are known for their good resistance to ageing, weathering, ozone attack and high flame resistance. The polar carbon-chlorine bond is the reason for the good media resistance in simple mineral oils and greases. The chemical resistance of CR vulcanizates corresponds approximately to that of nitrile rubber NBR with an acrylonitrile content of 18%. CR vulcanizates show good mechanical strength and can with- stand dynamic loads. PROPERTIES y thermal application range of –30 °C to +110 °C y good resistance in mineral oils with a high aniline point, fats, alcohol, glycol ether, water, diluted acids and bases y medium resistance in mineral oils, low-molecular aliphatic hydrocar- bons such as gasoline and isooctane y unstable in aromatics, chlorinated hydrocarbons, esters, ketones y flame-retardant y fatigue-resistant 56

3. General material selection and descriptions I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A +/- elastic CSM –30° +120° 0° – + high Cl SO2CL TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES CSM CHLORSULFONATED POLYETHYLENE re- sults from the reaction of thermoplastic polyethylene with chlorine and sulphur dioxide. Simultaneous sulphochlorination and chlorination make it possible to synthesize different types of CSM, which differ in terms of their chemical and tech- nical properties depending on the reaction process. CSM vulcanizates are highly elastic and very weather-resistant due to their satu- rated main chain. PROPERTIES As with chloroprene rubber (CR), the chlo- rine in CSM rubber leads to good flame resistance. CSM is highly resistant to acids and, with a high chlorine content, is also highly resistant to mineral oils. CSM is often used in the chemical indus- try for hoses and container linings. Other applications include colored cable sheath- ing, pond and roof films, coated fabrics, e.g. for inflatable boats, seals and mem- branes. y thermal application range –30 °C to +120 °C y good media resistance in hot wa- ter, steam, washing lyes, oxidizing media, acids, bases, polar organic media, ketones, glycol ether-based brake fluids y medium resistance in aliphatic hy- drocarbons and fats, strong bases y unstable in aromatic, chlorinated hydrocarbons and esters y highly elastic y flame-retardant R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 57 X E D N I

Materials and Process Engineering NBR –30° +100° +/- abrasion-resistant 0° – + medium + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES CN NBR NITRILE RUBBER also called ACRYLO NITRILE BUTADIENE RUBBER is a copolymer of acrylonitrile (ACN) and butadiene. The ratio of the two monomers can be varied within wide limits and significantly in- fluences the property profile of the NBR vulcanizates; ACN contents of between 18 and 50 percent are quite common. The polar nitrile groups ensure good oil and fuel resistance, which increases as the ACN content rises. Elasticity and com- pression set deteriorate with increasing acrylonitrile content, while gas tightness increases. The low-temperature flexibility also depends significantly on the monomer ratio and ranges from –40 °C at 18% ACN to –5 °C at 50% ACN. NBR vulcanizates have high mechanical properties, are wear-resistant and highly damping. NBR vulcanizates are used for hoses, floor coverings and in sealing technology: Seals of all kinds are always made from NBR if the maximum operating temperatures do not significantly exceed +100 °C and good oil resistance is required. Important fields of application include automotive and me- chanical engineering, oil and gas exploration and gas supply. In addition to static seals, NBR materials are also used to manufacture radial shaft seals – Simmerings and sealing elements for hydraulics and pneumatics. Freudenberg Sealing Technologies has been working with nitrile rubber longer than any seal manufacturer in the world. 58

3. General material selection and descriptions PROPERTIES y thermal application range of –20 °C to +100 °C y good media resistance in mineral oils, vegetable and animal oils and greases, light heating oil, diesel fuel y some materials are particularly resist- ant in hot water up to +100 °C, inor- ganic acids and bases at not too high concentrations and temperatures y medium media resistance in fuels with a high aromatic or alcohol con- tent, additivated oils y unstable in aromatic and chlorinated hydrocarbons, esters, polar solvents as well as in glycol ether-based brake fluids I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 59 X E D N I

Materials and Process Engineering XNBR –25° +100° 0° +/- abrasion-resistant – + medium + CN COOH TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES The main applications are drive belts, hydraulic hoses, roller covers and high- quality shoe soles. In sealing technology, XNBR is used when dynamic applications require special wear resistance and the setting behavior is of secondary impor- tance. XNBR CARBOXYLATED NITRILE RUBBER is a ter- polymer made from acrylonitrile (ACN), butadiene and a carboxylic acid. The main properties are comparable to NBR poly- mers, but XNBR is characterized by higher strength, better tear resistance and high dynamic load-bearing capacity. The ageing behavior, setting behavior and low-temperature flexibility are slightly worse compared to NBR. PROPERTIES y thermal application range of ‒25 °C to +100 °C y better compared to NBR: strength and abrasion resistance; better dynamic properties y worse compared to NBR: setting behavior, water and aging resist- ance 60

3. General material selection and descriptions R1 O O O N H R2 N H AU/EU O –35° +110° +/- elastic 0° – + medium + I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES AU – EU URETHANE RUBBER is a rubber that is poly merized from polyol, diisocyanate and chain extenders. Depending on the composition of the polyols used, a distinction is made between polyester urethane rubber – AU and polyether urethane rubber – EU. Vulcanizates made of urethane rubber are characterized by excellent wear and abra- sion resistance, high tensile strength, high elasticity and good resistance to high- energy radiation. They are resistant to oxygen, ozone, mineral oils and greases. Urethane rubbers are only partially resistant to aqueous media. On the other hand, EU rubbers are more resistant to hydrolysis than AU rubbers. The gas permeability is low and compa- rable to butyl rubber (IIR). Typical areas of application are wipers, gear wheels, rollers and roller coverings; these rubbers are also used in sealing technology. Another representative of the large class of polyurethane polymers is thermoplastic polyurethane (TPU): It belongs to the TPE polymer class and is used for seals in pneu- matics and hydraulics (see → “3.5 Thermo- plastic Elastomers (TPE)”, page 72.) PROPERTIES y thermal application range of –35 °C to +110 °C y good media resistance in mineral oils and greases, water-oil mixtures, sili- cone oils and greases y not resistant to polar solvents, chlo- rinated hydrocarbons, aromatics, glycol ether-based brake fluids, acids and bases, amines y also not resistant in hot water and water vapor R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 61 X E D N I

Materials and Process Engineering O O ECO CH2Cl –40° +140° 0° TEMPERATURE RANGE (°C) +/- low – + medium + MEDIA GAS- COMPATIBILITY PERMEABILITY ECO ETHYLENE OXIDE-EPICHLOROHYDRIN RUBBER is the main representative of the O class: it is a copolymer of ethylene oxide and epichlorohydrin. ECO vulcanizates are characterized by low gas permeability and good resistance to ozone and weathering combined with good low-temperature flexibility. They can withstand high dynamic loads and are also highly resistant to oil and fuel, while at the same time offering good re- sistance to acids and bases. PROPERTIES ECO vulcanizates have oil resistance comparable to nitrile rubber but are significantly more heat-resistant. They are used where good resistance to mineral oil and good resistance to weathering and ozone are required. The most important applications include oil and fuel hoses, roller covers and textile rubber linings, engine mounts as well as seals and diaphragms, especially for hy- draulic accumulators. y thermal application range of –40 °C to +140 °C y good media resistance in mineral oils and greases, vegetable and animal oils and greases, aliphatic hydrocarbons (propane, butane etc.) and gasoline as well as water y unstable in aromatic and chlorinat- ed hydrocarbons, flame-retardant hydraulic fluids of the HF D group 62

CSM ACM –30° +150° 0° C = C O = C O = C C O O C2H5 C4H9 CH2 CH2 O CH3 ACM ACRYLATE RUBBER is a copolymer of various acrylic acid esters with a small addition of another monomer required for cross-linking (CSM: cure site monomer). ACM vulcanizates are very resistant to ageing and ozone and show very good re- sistance to hot and highly additivated oils and lubricants. Depending on the monomer composition, they offer moderate to good low-temperature flexibility. PROPERTIES 3. General material selection and descriptions I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A +/- moderately elastic – + medium R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES Elastomers based on ACM are more heat-resistant than those based on NBR or CR, but have more moderate mechanical properties. ACM materials are mainly used in the automotive industry for hoses and seals: radial shaft seals – Simmerrings for gear- box sealing, O-rings and other molded parts such as valve cover or oil pan seals are made from ACM. y thermal application range of –30 °C to +150 °C y good media resistance in mineral oils, also in highly additivated engine, gear and ATF oils y unstable in aromatic and chlorinated hydrocarbons, alcohols, glycol ether- based brake fluids and flame-retard- ant hydraulic fluids y hot water, steam, acids, alkalis and amines have a destructive effect R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 63 X E D N I

Materials and Process Engineering O = C O CH3 COOH AEM ETHYLENE ACRYLATE RUBBER is a copol- ymer of ethylene and methyl acrylate. Compared to ACM vulcanizates, AEM elas- tomers are more heat-resistant and more flexible at low temperatures, and they usually offer higher strength. Chemical re- sistance to mineral oils is lower due to the ethylene component and is comparable to CR, while resistance to water and water/ glycol mixtures is higher than with ACM. Materials based on AEM are highly damping. PROPERTIES AEM –40° +160° 0° +/- damping – + medium + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES Like ACM, AEM rubber is also frequently used in the automotive sector: due to its high damping properties, oil and temper- ature-resistant vibration dampers are made from AEM vulcanizates. In addition to cable sheathing, AEM materials are used in hoses and seals for air ducting systems such as turbochargers as well as in engines and gearboxes. y thermal application range of –40 °C to +160 °C y good media resistance in additivated- and paraffin-based mineral oils y good weather and ozone resistance y unstable in ATF and gear oils, aro- matic-rich mineral oils, glycol ether- based brake fluid, esters, ketones and concentrated acids y in contrast to ACM, stable in water and water/glycol mixtures y high damping 64

3. General material selection and descriptions I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I EVM –40° +160° 0° R O F S L A E S Y R A T O R S N O T A C I I L P P A +/- ﬂame-retardant – + medium + R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY MECHANICAL PROPERTIES R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 65 X E D N I O O = C CH3 EVM ETHYLENE VINYL ACETATE RUBBER is a copolymer of ethylene and vinyl acetate with vinyl acetate contents of between 40 and 80%. EVM materials have good heat resistance and show a good balance between oil resistance and low-temper- ature flexibility. In contrast to ACM and AEM, EVM-based materials are not only highly resistant to water but also to vapor. EVM vulcanizates are halogen-free and yet flame-retardant; in the event of fire, the smoke gas density is low and the fire gases are not corrosive. Often blends with HNBR are used. One of the main areas of application for EVM vulcanizates is the cable industry due to its favorable fire behavior. Elastic floor coverings, roller coverings and the outer shells of fuel hoses are also made from EVM. EVM is also used in the adhesives industry, primarily as hotmelt and solvent adhesives and in sealing technology. PROPERTIES y thermal application range of –40 °C to +160 °C y good media resistance in water and water vapor y good resistance to weathering and ozone; sufficiently resistant in aliphatic hydrocarbons, mineral oils and greases y unstable in aromatic and chlorinat- ed hydrocarbons and esters y flame-retardant

Materials and Process Engineering FKM –20° 0° 0° +200° TEMPERATURE RANGE (°C) +/- low – + high MEDIA GAS- COMPATIBILITY PERMEABILITY In addition to FKM, there is the class of FEPM rubbers synthesized from TFE and propylene. They have a fluorine content of 57%, show excellent resistance to hot water, steam and basic media such as amines and amine-containing liquids with medium resistance to mineral oils. FKM-based materials are used in the auto- motive and commercial vehicle industry, in the aerospace industry, in food appli- cations and in oil production and plant engineering. In addition to turbocharger and fuel hoses, dynamic and static seals such as valve stem seals, radial shaft seals – Simmerrings, molded parts, O-rings, flat gaskets and diaphragms are manu- factured from FKM vulcanizates. Under the name Fluoroprene XP, Freuden- berg Sealing Technologies offers a special range of materials for use in the process and food industry whose properties sig- nificantly exceed those of conventional FKM materials. F F F F F CF3 FKM FLUORORUBBER is synthesized by poly- merization of vinylidene fluoride (VDF) and optional use of variable proportions of other monomers such as hexafluoro- propylene (HFP), tetrafluoroethylene (TFE) and perfluoromethyl vinyl ether (PMVE). Co-, ter- or tetrapolymers with different structures and fluorine contents of 65 to 71% and thus different media resistance and low-temperature flexibility (standard types –20°C; special grades –40°C) can be produced. FKM rubbers can be cross-linked using diamines, bisphenols or organic peroxides, depending on the type. The special importance of FKM materials lies in their high temperature resistance and chemical stability, both of which are the result of the high stability of the car- bon-fluorine bond. The gas permeability is low, the resistance to ozone, weathering and light cracking is outstanding. FKM vulcanizates are flame-retardant; bisphe- nolic cross-linked grades are more resistant to temperature and wear, but less resistant to acids and steam than peroxide cross- linked grades. Amines have a destructive effect on FKM materials, and standard FKM vulcanizates swell strongly in ketones and esters. 66

3. General material selection and descriptions PROPERTIES y thermal application range of –20 °C to +200 °C y good media resistance in mineral oils and greases (especially highly additivated engine oils), aliphatic and aromatic hydrocarbons such as gasoline y good resistance to weathering, hot air and ozone; sufficiently stable in aliphatic hydrocarbons, mineral oils and greases y FKMs with special peroxide cross- linking are also highly resistant to alcohols, hot water, steam and alco- hol-based fuels y unstable in ketones, esters, amines and additive oils and fats with a high amine content y low gas permeability I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 67 X E D N I

Materials and Process Engineering F F R F F F F F FFKM PERFLUORINATED RUBBER is produced by using special perfluorinated (i.e. com- pletely hydrogen-free) monomers and special compounding and processing techniques. FFKM combines the elastici- ty of an elastomer with a media and tem- perature resistance that surpasses FKM materials even further and comes very close to PTFE ("elastic PTFE"). FFKM com- pounds are not easy to process, the vul- canizates have poor low-temperature flexibility and the physical properties are rather moderate; FFKM materials are very expensive. FFKM vulcanizate is used wherever temperatures prevail that cannot be reached by any other elastic material or PROPERTIES FFKM –20° +/- abrasion-resistant 0° 0° +300° – + high + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES where near-universal chemical resistance is required. High-performance materials based on FFKM are mainly used as sealing materi- als in the chemical, oil production and processing industries, in apparatus and power plant construction and in the aerospace industry. Due to their high purity, vulcanizates made from FFKM are also used in the semiconductor industry and photovoltaics, in medical technology and in the pharmaceutical and food sectors. Freudenberg Sealing Technologies has been offering customized sealing solutions made from the company’s proprietary perfluoro- elastomer Simriz® for many years. y thermal application range for standard types of –10 °C to +230 °C (special grades –30 °C to +320 °C) y nearly universal chemical resistance, including to esters and ketones, amines, concentrated acids and bases y not resistant to alkali metals and per- fluorinated hydrocarbon materials y combines the durability of PTF E with the elasticity of an elastomer 68

3. General material selection and descriptions I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I HNBR –20° +150° 0° R O F S L A E S Y R A T O R S N O T A C I I L P P A +/- abrasion-resistant – + medium + R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES CN HNBR HYDROGENATED ACRYLONITRILE-BUTA- DIENE RUBBER is obtained from NBR pol- ymers by a subsequent hydrogenation step in which the double bond content of the butadiene component is reduced to < 1 – 7%. This increases the heat and oxi- dation stability, especially in the case of peroxide cross-linking. High mechanical strength even at high temperatures as well as improved abrasion resistance and good dynamic resistance characterize the materials produced from this material. The media resistance is similar to that of NBR. As with NBR, there are CARBOXYLATED HNBR RUBBER, XHNBR with improved abrasion and tear resistance; also grades with special heat resistance and low-tem- perature grades. HNBR is often used in the automotive sector as a standard material for timing belts and hoses. However, this material is also used as a rod or piston seal, and radial shaft seals– Simmerrings are also made from HNBR. Due to its good resistance to crude oils, HNBR is also a common sealing material in oil exploration. PROPERTIES y thermal application range of –20 °C to +150 °C y media resistance comparable to NBR y very good weather and tempera- ture resistance y resistant to abrasion and fatigue R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 69 X E D N I

Materials and Process Engineering CH3 CH = CH2 CH3 R VMQ: R = – CH3 Si O Si O FVMQ: R = – CH2 – CH2 – CF3 PVMQ: R = O VMQ – FVMQ SILICONE RUBBERS are synthesized from different siloxane monomers. The polymer backbone consists alternately of oxygen and silicon atoms. VMQ vulcanizates are characterized in particular by high thermal stability and good low-temperature flex- ibility as well as very good resistance to oxygen, ozone and high-energy radiation. Tear resistance and abrasion resistance are moderate, the temperature depend- ency of the technological properties is low compared to other elastomers and the permeability for gases is significantly higher. Materials based on VMQ are highly electrically insulating, flame-retardant and physiologically inert. VMQ vulcaniza- tes are degraded by depolymerization at high temperatures in the absence of oxygen. PHENYL-VINYL-METHYL-POLYSILOXANE, PVMQ is a particularly cold-flexible variant of silicone rubber that retains its elastic properties down to –90 °C. FLUOROSILICONE RUBBER, FVMQ is com- posed of side groups that contain fluorine. Elastomers made from FVMQ are consid- erably more resistant in fuels, mineral, synthetic and aromatic oils than those VMQ –50° 0° 0° +/- elastic – + +200° medium + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES made from VMQ and PVMQ, their oper- ating temperatures range from –55 °C to +175 °C. Due to their purity and physiological in- ertness, silicone elastomers are used in the pharmaceutical industry, medical technology and in contact with food. Due to their high electrical resistance, they are used as potting compounds in electronics and as insulators on overhead power lines. In addition, hoses, membranes, cables and seals in the automotive and electrical in- dustries are made from VMQ. FVMQ vulcanizates are particularly well suited for inner hose layers (e.g. in turbo- charger hoses) and for seals in contact with fuels. Other fields of application include natural gas plants and natural gas con- veying equipment as well as aerospace technology. 70

3. General material selection and descriptions PROPERTIES y thermal application range of VMQ –50 °C to +200 °C y good media resistance in mineral oils, animal and vegetable fats (com- parable to CR materials) and in glycol ether-based brake fluids y can be used in water up to +100 °C; sufficiently resistant in aqueous salt solutions, monohydric and poly- hydric alcohols y unstable in low molecular weight esters and ethers, aromatic hydro- carbons y concentrated acids and bases, water and steam at temperatures above +100 °C and under pressure have a destructive effect y flame-retardant, not very gas-tight I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 71 X E D N I

Materials and Process Engineering 3.5 THERMOPLASTIC ELASTOMERS (TPE) TPE-O –40° 0° +100° +/- weather and ageing resistant – + medium TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY MECHANICAL PROPERTIES TPE-O POLYOLEFIN-BASED ELASTOMER ALLOYS WITH A NON-CROSS-LINKED RUBBER PHASE: Elastomer alloys based on EPD M and isotactic polypropylene (iPP) are cur- rently the most important TPE-O material class for technical applications. The iPP forms semi-crystalline phases in the ma- terial and thus enables the material to be processed thermoplastically above the melting temperature. TPE-O are charac- terized by their high resistance to polar media, high resistance to weathering and ageing and their low density. The products cannot be used above +100 °C. TPE-O are mainly used for haptic applica- tions, in particular elastic ergonomic soft- touch handles (toothbrushes, tools and hair dryers, for example). They are also used in car interiors and for children's toys. PROPERTIES y thermal application range of –40 ˚C to +100 °C y good media resistance in water, washing lyes, acids and glycol- based brake fluids y low resistance to mineral oils, greases and gasoline y good resistance to weathering and ageing 72

3. General material selection and descriptions I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I TPE-V +120° –50° 0° R O F S L A E S Y R A T O R S N O T A C I I L P P A +/- weather and ageing resistant – + medium R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY MECHANICAL PROPERTIES TPE-V POLYOLEFIN-BASED ELASTOMER ALLOYS WITH A NON-CROSS-LINKED RUBBER PHASE: Like TPE-O, TPE-V are elastomer alloys made of thermoplastic and elasto- mer material, whereby the latter is often chemically cross-linked in the melt dur- ing production (dynamic vulcanization), resulting in the formation of stable elas- tomer domains. The size and degree of cross-linking of the elastomer domains are decisive for the mechanical properties of the material. EPDM/PP alloys, which are characterized by their good resistance in polar media and good resistance to weathering and ageing, are increasingly used in technical applications. Special grades are also available for applications in non-polar media. Conventional TPE-Vs generally cannot be used above +120 °C. TPE-V based on EPDM/PP are used for grommets, brake hose sheathing, plugs and cable glands. They are also widely used in consumer goods and in the healthcare sector. TPE-V is used to pro- duce profile seals for the automotive and construction industries. Molded seals of all kinds in medical and food technology, in drinking and wastewater, but also in household appliances are made from TPE-V. PROPERTIES y thermal application range of –50 ˚C to +120 °C y high media resistance in (hot) water, washing lyes, acids and glycol-based brake fluids y special grades for media resistance in oils and greases y high resistance to UV, weathering and ageing y increased mechanical strength values R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 73 X E D N I

Materials and Process Engineering n m n TPE-S –40° 0° +80° +/- scratch-resistant – + low TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES TPE-S STYRENE BLOCK COPOLYMERS: TPE-S are characterized by a three-block structure consisting of thermoplastic polystyrene hard segments as end blocks and an elas- tomer middle block. The following sty- rene block copolymers are differentiated according to the type of middle block: Butadiene (SBS), isoprene (SIS), ethylene/ butylene (SEBS), ethylene/propylene (SEPS), polyisobutylene (SIBS). The ratio of polystyrene to polydiene segments de- termines the mechanical properties of the material; its stiffness increases with increasing polystyrene content. The elastomer segment, on the other hand, significantly determines the material's resistance to thermo-oxidative ageing at the service temperature. Ready-to-use TPE-S materials are produced by com- pounding with other plastics, plasticizer oils, fillers and other additives. The softening point of the polystyrene hard phase deter- mines the application temperature limit: creep and loss of tensile strength occur above +100 °C. TPE-S are used to modify bitumen and asphalt. They are used as adhesives and hot-melt adhesives, in children's toys, in packaging and elastic soft-touch handles. Special grades based on SEBS and SEPS are used in medical technology, in food and drinking water applications and in car interiors. Simple sealing applications can also be realized with styrene block co- polymers. PROPERTIES y thermal application range of –40 ˚C to +80 °C y high media resistance in water, washing lyes, acids and glycol- based brake fluids y high resistance to UV, weathering and ageing y increased mechanical strength values 74

3. General material selection and descriptions I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I O O O O R O X X O o N H N H O n O 4 N H N H m TPE-U THERMOPLASTIC POLYURETHANE ELASTO- MERS: TPE-U are multiphase block co- polymers obtained from the reaction be- tween isocyanates, chain extenders and polyols. The long-chain polyol forms the soft segments, which determine the material's low-temperature properties and resistance to media and ageing. Iso- cyanate and chain extenders (e.g. short- chain diols) form thermally reversible physical cross-linking points. TPE-U are among the materials that are particular- ly characterized by their high strength, high flexibility, high resilience and low abrasion. They are resistant to fats and oils at extremely low temperatures (–50 °C) and high temperatures (up to +120 °C for short periods). PROPERTIES TPE-U +120° –50° 0° R O F S L A E S Y R A T O R S N O T A C I I L P P A +/- abrasion-resistant – + high R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES This material is therefore often used in hydraulic applications. However, TPE-U is not resistant to acids or hot water. TPE-U is used to make sporting goods such as parts of sports shoes and ski boots, and certain types are suited for contact with food and skin. Hoses, cable sheathing, belts, films and profiles are also made from TPE-U, as are high-quality instrument panels. In sealing technology, TPE-U materials are used for highly stressed diaphragms and especially for rod and piston seals and wipers for hydraulics and pneumatics. y thermal application range of –50 ˚C to +120 °C y high media resistance in greases and oils y unstable in acids and hot water y very high mechanical strength values y high resilience y highly resistant to abrasion and fatigue R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 75 X E D N I

Materials and Process Engineering O O 4 O O O n O o O m O TPE-E THERMOPLASTIC COPOLYESTER-POLY- ETHER-ELASTOMERS: TPE-E are multi- block copolymers that consist of oxyalky- lene glycol units of different lengths that are connected to each other via polyester blocks. The polyether segments form the soft elastomer phase, while the polyester segments form physical cross-linking points. TPE-E are particularly characterized by their durability under dynamic loads, high strength and wear resistance. They have good low-temperature flexibility and are thermally resistant up to +120 °C. They are also resistant to non-polar media, but are not resistant to concentrated acids and PROPERTIES TPE-E +120° –65° 0° +/- fatigue-resistant – + high TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY MECHANICAL PROPERTIES alkalis as well as hot water. TPE-E materials are a halogen-free and flame-retardant alternative to PVC. Cable insulation and sheathing, connec- tors and suspension systems are made from TPE-E, as are rollers and belts. TPE-E are used in air ducts, pipes and hoses. They are also used in sports equipment and medical technology. In the sealing sector, TPE-E are the ideal choice for dynamically highly stressed components subject to buckling, such as axle boots and bellows. y thermal application range of –65 ˚C to +120 °C y high media resistance in lubricants and oils y unstable in concentrated acids and alkalis, hot water and steam y very high mechanical strength values y high resilience across a wide tem- perature range y fatigue resistant 76

3. General material selection and descriptions I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I TPE-A –40° +120° 0° H N O O 11 n 4 4 m O O O R O F S L A E S Y R A T O R S N O T A C I I L P P A +/- impact-resistant – + medium R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES TPE-A POLYETHER POLYAMID E BLOCK COPOLY- MERS: TPE-A are block copolymers in which the polyether blocks form the elastomeric phase, while the polyamide blocks act as the thermoplastic hard phase. They are characterized by high flexibility and high resilience over the entire service temperature range. In addition, TPE-A have good abrasion and sliding properties and high notched impact strength even at low temperatures. They are only partially resist- ant to acids, alkalis and non-polar media. They are used in medical technology, for example, and are temperature-resistant up to +120 °C. TPE-A are used in sporting goods such as the outsoles of sports shoes and parts of ski boots. Conveyor belts, belts, transmission parts such as gear wheels, pressure lines and airbag covers are made from TPE-A ma- terials. Special grades are used in medical technology, particularly in catheters. PROPERTIES y thermal application range of –40 ˚C to +120 °C y limited resistance to acids, lyes, oils and greases y high mechanical strength values y high notched impact strength y high elasticity y special grades for use in medical technology R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 77 X E D N I

Materials and Process Engineering 3.6 TECHNICAL THERMOPLASTICS PE: PP: PO –40° 0° +110° +/- ﬂexible – + high TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES PO POLYOLEFINS: Polyethylene PE and poly- propylene PP are the most important representatives of the polyolefin class. There are many different grades within both families of materials, the vast majority of which are semi-crystalline. Polyolefins exhibit good wear and friction behavior as well as good insulating properties. They are resistant to many different media, to near- ly all non-polar liquids such as oils, greases and gasoline, but also to water, acids, bas- es and alcohols. They also have very low water absorption, which makes them ide- al for use in the process industry. cable sheathing and other non-conductive components in the electrical industry as well as tubing and fibers for surgical sutures. PP are also mainly used in the packaging industry and in the food and cosmetics sectors. Wastewater pipes are also made of PP, as are housings for small electrical appliances, car body parts (bumpers) and garden furniture. PP fibers are used in moisture-repellent and mite-proof mat- tress covers, but also in clothing, as poly- propylene fabrics are breathable and dry very quickly. PE and PP are the most commonly used thermoplastics in the world with a wide range of everyday applications. Due to their high flexibility, polyolefins are also ideal for sealing, e.g. as screw caps for beverage bottles. The main areas of application for PE are bags and films for packaging, canisters, 78

3. General material selection and descriptions PROPERTIES y thermal application range: PE: –60 °C to +90 °C; PP: –40 °C to +110 °C y excellent wear resistance y very good friction behavior y excellent insulation properties y low water absorption y high media resistance (e.g. to acids, diluted bases, oils and greases); special grades with food and drink- ing water approvals y higher flexibility than other thermo- plastic materials such as PA, POM and PEEK I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 79 X E D N I

Materials and Process Engineering O POM –50° 0° +110° +/- low friction – + medium + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES POM POLYOXYMETHYLENE: POM is a semi-crys- talline plastic and one of the mechanical- ly highly resilient thermoplastics. Thanks to its rigidity, hardness and strength, combined with excellent dimensional stability up to approx. +80 °C, it can often replace parts made of die-cast metal, brass or aluminum. Due to its high resilience, POM is also frequently used for snap-fit connections and spring elements. Its low water absorption is remarkable. Compared to molded parts made of polyamide, it ensures better dimensional stability even under the influence of moisture. POM is used in a wide range of applications in mechanical engineering and the auto- motive industry: gear wheels, parts of tank caps and pumps, valves, fittings, screws and nuts, but also precision parts for elec- trical engineering are made from POM. POM is also used for door and window handles as well as for zippers, tooth- brushes and children's toys. PROPERTIES y thermal application range: approx. –50 ˚C to +110 °C y excellent friction and wear behavior y low water absorption y high media resistance to many or- ganic solvents, oils, weak acids, bases and alcohols y unstable in strong acids and oxidizing agents y special grades with food and drink- ing water approvals 80

3. General material selection and descriptions I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I O O PK POLYKETONE is a semi-crystalline thermo- plastic. It combines the good sliding and friction properties, low water absorption and excellent hydrolysis resistance of POM with the higher melting temperature of PA6. Polyketones are used in similar appli- cations to POM, e.g. in components and gears for fully automatic coffee machines or in switches and housings in the elec- tronics industry. The high wear resistance and good barrier properties against oxygen and many media PROPERTIES PK –40° +120° 0° R O F S L A E S Y R A T O R S N O T A C I I L P P A +/- ﬂexible – + medium R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES as well as its generally good chemical re- sistance allows it to be used in precision parts in the aerospace and automotive industries as well as in shipbuilding and mechanical engineering, in components of fuel systems, for example. PK housings are often provided with an elastomer seal in 2K processes. Polyketone is used in sealing technology, as a hydraulic seal, for example. y thermal application range: approx. –40 ˚C to +120 °C y excellent friction and wear behavior y low water absorption y high media resistance to many organic solvents, oils, acids, weak bases and alcohols. y unlike POM, PK is highly resistant to acids y strong bases can attack PK y special grades with food and drinking water approvals or a flame-retardant finish R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 81 X E D N I

Materials and Process Engineering PA: PA 6.6: N N O O N O PA –40° +130° 0° +/- stiﬀ – + medium TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES PA6.6 PA ALIPHATIC POLYAMIDES comprise a large class of different polymers. The most im- portant representatives are PA 6, PA6.6, PA 4.6, PA11 and PA12. Polyamides are tough plastics with high strength and stiffness, excellent impact resistance and good abrasion and wear resistance. PA6, PA11 and PA12 are synthesized from one monomer, where the number indicates the number of carbon atoms between the nitrogen atoms in the main chain. PA6.6 and PA4.6 are produced from two differ- ent monomers, the diamines and the dicarboxylic acids, so that the number of carbon atoms between the nitrogen atoms and the carbonyl functions can differ. PA6, PA6.6 and PA4.6 are mostly used for glass fiber reinforced molded parts; The range of applications is broad and extends from gear wheels to truck oil pans. These polyamides absorb several percent by weight of water under ambient conditions, which must be taken into account when designing components and makes high dimensional stability difficult. PA6 is also processed in large quantities into fibers and textiles. Fishing lines are also made of PA6. PA11 and PA12 absorb much less moisture than the aforementioned types. Due to their high diffusion resistance, they are used as a barrier layer in fuel hoses. In sealing technology, seals made of elas- tomers, liquid silicone (LSR) or TPE are often directly molded onto PA housings using 2K processes, opening up complete- ly new product designs. There are also pneumatic seals made of PA. 82

3. General material selection and descriptions PROPERTIES y thermal application ranges: PA11 and PA12: –70 °C to +110 °C PA6: –40 °C to +130 °C PA6.6: –40 °C to +140 °C PA4.6: –40 °C to +180 °C y high mechanical strength and stiff- ness y very good wear and friction behavior y low creep tendency y very good resistance to lubricants and gasoline, resistant to hydrocar- bons (aliphatic, cyclic and aromatic) y resistant to halogenated solvents and superheated steam y unstable in organic and mineral acids and bases y many special grades, e.g. with flame protection or friction optimization I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 83 X E D N I

Materials and Process Engineering O O O O O PBT POLYBUTYLENE TEREPHTALATE is a semi- crystalline, thermoplastic polyester mate- rial. PBT is characterized by high stiffness and strength, good sliding properties and very low water absorption. This makes it ideal for dimensionally stable housing and structural components and connectors. Typically, grades with medium to high glass fiber contents are used here. Many products made of PBT are used in the automotive and electrical industries. PBT can be given an excellent flame- retardant finish, so that even the high fire PROPERTIES PBT –50° +130° 0° +/- stiﬀ – + medium TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES protection requirements in electric vehicles can be met. Due to its good tribological properties, in particular its good sliding behavior, PBT is also used in moving parts. Types that are suited for drinking water are used in the sanitary sector, in shower heads, for example. In sealing technology, PBT housings are usually overmolded with elastomers or liquid silicone (LSR), thus reducing the assembly effort. y thermal application range of –50 °C to +130 °C y good tribological properties y very low water absorption y resistant to lubricants containing mineral oil and all hydraulic fluids, diluted bases, acids and alcohols y unstable in hot water and strong acids and bases y special grades with approvals for contact with drinking water or flame- retardant types 84

3. General material selection and descriptions 3.7 HIGH-PERFORMANCE THERMOPLASTICS PPS –100° 0° 0° +/- stiﬀ – + +240° medium + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES flame retardant. The UV and weather stability is low. PPS is available in two structural variants: PPS with purely linear chains has a higher toughness, while PPS grades with branched chains have slightly higher strengths. Due to its excellent mechanical properties, PPS is used as a molded part in demanding applications. Pump housings and lamp bases are made from PPS. The material is frequently used in the electrical and auto- motive sectors, as well as in aerospace and oil production. y poor resistance to hot steam and low resistance in strongly oxidizing media y low UV and weather resistance y inherently flame-retardant S PPS POLYPHENYLENE SULPHID E is a semi- crystalline thermoplastic whose aromatic monomer units are linked to each other via sulphur bridges. At up to 70%, the degree of crystallization is significantly higher than that of most other semi-crystalline plastics. The drop in mechanical properties at the glass transition is therefore lower with PPS than with other thermoplastics. The material is characterized by very good mechanical properties and high heat deflection temperature as well as high chemical resistance and stiffness, is electrically insulating and is naturally PROPERTIES y thermal application range of –100 °C to +240 °C y good tribological properties y very low water absorption y good chemical resistance to alcohols, ketones, aliphatic hydrocarbons, acids and alkalis I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 85 X E D N I

Materials and Process Engineering O O O NR N PPA –40° +180° 0° +/- stiﬀ – + medium + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES PPA PARTIALLY AROMATIC POLYAMIDES, also known as "polyphthalamides" or " partially aromatic polyamides," have an aromatic structural element in their molecular structure, usually benzenedicarboxylic acids; the most important representa- tives are PAMXD6, PA6T/6I, PA 6T/66, PA 10T/X, PA4T, PA9T. PPAs are semi-crystalline, highly temper- ature-resistant and have high glass tran- sition temperatures; this means they have good heat resistance. The materials have high stiffness and tensile strength, good dimensional stability, are creep- resistant and have little tendency to warp. Polyphthalamides have better chemical resistance than standard polyamides and have good corrosion resistance. They can be used in contact with biodiesel, brake fluids, synthetic engine oils, gear and transformer oils and glycols. PPAs are often used as metal substitutes in structural components, often where high heat resistance combined with high mechanical stability is required, e.g. in the engine compartment or in pumps and supply lines. The grades used are usually filled with large quantities of glass or carbon fibers. Due to their low moisture absorption, partially aromatic polyamides are used in sanitary systems, e.g. as housings for thermostats, valve bodies in shower fittings and in electronics as connectors and in household electrical appliances. PPAs are also used in medical technology and in contact with drinking water and foodstuffs, and as carrier parts in taps and shower heads. In sealing technology, PPAs are usually used for housing components onto which elastomer seals are molded. 86

3. General material selection and descriptions PROPERTIES y thermal application range: –100 °C to +180 °C, special grades also higher y high stiffness, high modulus of elas- ticity, creep-resistant, heat-resistant y good wear resistance y lower water absorption than PA6 and PA4.6 y good chemical resistance to a wide range of oils, greases and other hydro- carbons y unstable in acids and alkalis y highly insulating I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 87 X E D N I

Materials and Process Engineering O O N O O O O PEI POLYETHERIMIDES are amorphous high- performance plastics that are characterized by very high stiffness even at high tempera- tures and have very good creep resistance. The mechanical stability of PEI can be significantly increased by adding glass fibers. The material is highly resistant to acidic chemicals, while ketones and chlo- rinated hydrocarbons attack PEI. PEI are highly resistant to high-energy radi- ation and have the highest flame resistance of all non-fluorinated polymers. In normal atmosphere, PEI are non-flammable. PROPERTIES PEI –100° 0° 0° +/- ﬂame-retardant –– + +170° medium + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES They only start to burn when the oxygen content exceeds 40%. This is why PEI materials are often used in aircraft interiors in the aerospace industry, as smoke gas development in the event of fire is minimal. Because many properties are very constant over a wide range of temperatures and electrical frequencies and PEI materials have high dielectric strength, PEI are used in the electronics industry for coils and fuses. Diaphragms and films are also made from PEI. y thermal application range of –100 °C to +170 °C y adequate tribological properties y high stiffness, good creep resistance y PEI absorbs water, but slightly less than polyamides y good chemical resistance, good hy- drolysis resistance y inherently flame-retardant y highly electrically insulating 88

3. General material selection and descriptions I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I PEEK –65° 0° 0° O O O O O O R O F S L A E S Y R A T O R S N O T A C I I L P P A +/- wear-resistant – + +260° medium + R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES PEEK POLYETHERETHERKETONE is a semi-crys- talline thermoplastic with almost universal chemical resistance to nearly all organic and inorganic chemicals. Exceptions in- clude acidic oxidizing media such as concentrated nitric and sulphuric acid as well as UV radiation in combination with atmospheric oxygen. While the chemical resistance approaches that of PTFE, PEEK shows clearly superior mechanical properties and maximum wear resistance compared to PTFE, which can be further optimized by add- ing various fillers such as glass or carbon fibers. The material can also be processed using conventional injection molding processes. The material is often used in applications with hot water or steam, in steam tur- bines, for example. Due to its high tem- perature resistance and resistance to aggressive chemicals, it is particularly well suited for the process industry. PEEK is also used in engine, compressor and pump components, drives, valves, support and backing rings and many other areas. Some material variants have the relevant approvals for applications in the food and beverage industry. PEEK is also used in medical technology to create permanent implants. PROPERTIES y thermal application range: –65 °C to +260 °C y nearly universal chemical resistance y excellent mechanical strength y highest wear resistance y not resistant to strongly oxidizing chemicals and special solvents y special grades for use in electronic applications and medical technology R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 89 X E D N I

Materials and Process Engineering PVDF: F F ETFE: F F ETFE/PVDF –30° +150° 0° +/- extremely durable – + high TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY CHEMICAL PROPERTIES PVD F has mechanical properties compa- rable to POM and is quite gas-tight. Most other partially fluorinated thermoplastics, including ETFE, have significantly lower stiffnesses and higher elongations. This makes them ideal for sealing technology, but also for membranes and films, which are increasingly being used in architecture. In addition to PVD F and ETFE, there are a number of other partially fluorinated thermoplastics, but most of these are optimized for very specific applications and are not widely used. F F ETFE PVDF The two most important representatives of the polymer class of partially fluori- nated thermoplastics are ETHYLENE TETRAFLUORO ETHYLENE COPOLYMER ETFE and POLY VINYLID E FLUORID E PVDF. Both are semi- crystalline plastics. In con- trast to the most common fluoroplastic PTFE, partially fluorinated thermoplastics can be processed using most thermoplas- tic shaping processes such as injection molding, extrusion or welding. However, processing requires special measures such as the use of acid-resistant steels in contact with the hot thermoplastic melts and sufficient extraction and ventilation. The mechanical properties of the partially fluorinated thermoplastics can be further improved by using fillers such as carbon fibers. 90

3. General material selection and descriptions PROPERTIES y thermal application ranges: PVD F –30 °C to +150 °C y ETF E –100 °C to +150 °C y adequate to good tribological prop- erties y no water absorption y high thermal expansion coefficient limits dimensional stability y very comprehensive chemical resist- ance y not resistant to alkali metals, fluor- inated solvents and specific acids and bases y inherently flame-retardant I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 91 X E D N I

Materials and Process Engineering PFA: FEP: F C F F C F F F F C F F F C O m FC F CF3 F F F n F F PFA FEP The two most important representatives of the polymer class of fully fluorinated thermoplastics are PERFLUOROALKOXY COPOLYMERS PFA (copolymers made of tetrafluoroethylene and perfluoroalkoxy- vinyl ether) and FLUORINATED ETHYLENE- PROPYLENE COPOLYMER FEP (copolymers made of tetrafluoroethylene and hexa- fluoropropylene). Both are semi-crystalline plastics that are largely chemically inert. Just like the partially fluorinated plastics described above, fully fluorinated thermo- plastics can also be processed using most thermoplastic molding processes, although processing requires taking a few special measures. Fully fluorinated thermoplastics are sometimes marketed as "thermoplas- tic PTFE." The designation is appropriate for temperature and chemical resistance. PFA/FEP +/- extremely durable 0° – + –200° +250° high + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES Certain mechanical properties such as flexural fatigue strength or even scratch resistance are significantly lower, however. This is due to the fact that the polymer chains of PTFE are significantly longer. The mechancal properties can be further improved by using fillers such as carbon fibers. Fully fluorinated plastics have significantly lower moduli and higher elongation than non-fluorinated types and are susceptible to high-energy radiation. PFA and FEP are transparent, highly elec- trically insulating and UV-resistant. They are used in a wide range of applications in the aerospace, petrochemical, electronics and semiconductor industries as well as in medical technology and the food industry. 92

3. General material selection and descriptions PROPERTIES y thermal application ranges: PF A –200 °C to +240 °C FEP –200 °C to +200 °C y adequate to good tribological prop- erties y no water absorption y high thermal expansion coefficient restricts dimensional stability y very comprehensive chemical resist- ance, UV-resistant y not resistant to alkali metals, fluor- inated solvents y inherently flame-retardant y many grades are approved for the pharmaceutical and food sectors I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 93 X E D N I

Materials and Process Engineering F F F F PTFE +/- low friction 0° – + –200° +260° high + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES PTFE POLYTETRAFLUOROETHYLENE is another fully fluorinated, semi-crystalline plastic. In addition to its complete fluorination, its outstanding properties result from the significantly longer molecular chains compared to other polymers. As a result, PTFE cannot be melted and cannot be processed using classic thermoplastic shaping processes such as injection mold- ing. A semi-finished product is usually produced in a sintering process and then machined into the final geometry. Its property profile is comparable to that of FEP. It is chemically highly resistant; only liquid alkali metals and some fluorine compounds attack PTFE at higher pressures and temperatures. Nothing sticks to the smooth surface of PTFE (anti-adhesive). PTFE is not very resistant to high-energy radiation and is difficult to adhere to. Due to its high cold flow and low resistance to abrasion and wear, pure PTFE is only used in sealing technology for low requirements. PTFE mixtures with special fillers are used for high-performance seals. The most im- portant fillers include bronze and steel, glass fibers, glass beads, carbon fiber, graphite, ceramic fillers and solid lubricants such as molybdenum sulfide. PTFE materials are indispensable in nearly all areas of industry. PTFE applications include mechanical engineering, the chemical industry and plant construction, electrical and semiconductor technology, the pharmaceutical and food industries as well as medical and analytical tech- nology. 94

3. General material selection and descriptions PROPERTIES y thermal application range: approx. –200 °C to +260 °C y nearly universal chemical resistance y best electrical insulation values and good dielectric properties y resistant to light and weathering y no ageing y physiologically harmless in the range up to +200 °C y very good sliding properties, no "stick-slip" effect y self-lubricating, so that bearings and motion seals can also run dry under certain conditions y anti-adhesive behavior y non-flammable y no water absorption y grades with food and drinking water approval are available I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 95 X E D N I

Materials and Process Engineering O N O N O O O O PAI –100° 0° 0° +/- wear-resistant – + +260° medium + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES PAI POLYAMIDE-IMID E is an amorphous ther- moplastic that has various aromatic structural units in the polymer chain, making it one of the most thermally sta- ble polymers with a carbon backbone. After molding, articles made of PAI must be cross-linked in a complex 17-day tem- pering process. Only this thermal post-treatment gives the products their unique mechanical properties, which are retained at temperatures of up to +260 °C. In addition to a high degree of tensile and compressive strength, PAI exhibits low thermal expansion, which enables very dimensionally stable components. There are friction and wear-optimized grades that can be used at temperatures up to +275 °C, as well as grades with glass and carbon fibers for optimized stiffness and strength. These properties, together with the in- herent flame retardancy, make PAI the ideal choice for many applications in the aerospace industry and in power plant technology. Highly heat-resistant coatings are also made from PAI. Applications can also be found in the automotive industry for extreme tribo- logical requirements such as rectangular sealing rings and thrust washers. PROPERTIES y thermal application range –100 °C to +260 °C y high compressive strength and creep resistance y excellent tribological properties y good chemical resistance y susceptible to hydrolysis at higher temperatures y inherently flame-retardant 96

3. General material selection and descriptions 3.8 DUROMERS Duromers are highly cross-linked materials that neither soften nor melt in the heat. After curing, they are more dimensionally stable than non-cross-linked plastics. Duromers have the lowest tendency to creep and the highest strength of all poly- mer materials. They are particularly attrac- tive for structural applications because their thermal expansion is in the same order of magnitude as that of steel and aluminum, and can be adjusted within limits. Due to their brittleness, duromers are often filled with fibers. For example, short and long fibers (BMC), continuous fibers (SMC) and resin-impregnated fabrics and scrims (prepregs) are used. The type of fiber reinforcement determines what processing methods are possible. Most duromer components are manufac- tured using compression molding (SMC, prepregs). However, granulates suited for injection molding (BMC) are also increas- ingly available. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 97 X E D N I

Materials and Process Engineering CH2 N CH2 N CH2 N CH2 N C=O C=O N CH2 N CH2 N CH2 N CH2 C=O C=O UF Urea-formaldehyde resins are among the oldest class of industrially used duromers, the aminoplastics. The oligomers (some- times polymers) are produced by a con- densation reaction of methylol ureas with urea. The cross-linking is acid-catalyzed (with latent curing catalysts). The thermal application range is rather restricted at +80 °C for continuous use. UF resins are characterized by good color- ability and lightfastness. They are also highly scratch-resistant and very cost-ef- fective. Like most duromers, UF resins are quite brittle and stiff. UF resins are resistant to organic solvents, greases and oils as well as cold water. UF resins are not resistant to hydrolysis and UF +80° +/- colorfast 0° – + –200° low + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY MATERIAL PROPERTIES are therefore not suited for even weak acids and bases, or for hot water. In addi- tion, they are prone to stress cracking due to high shrinkage. UF resins are widely used in the wood and furniture industry, for door and wall cov- erings as well as for decorative laminate, pressed and façade panels, for example. They are also used in textile finishing and as a binder for paper. PROPERTIES y thermal application range: –200 °C to y unresistant to acids and bases, un- +80 °C y cost-effective y good weather and light resistance y resistant to many solvents, oils and greases, as well as cold water suited for hot water applications y high gloss, high scratch resistance y brittle 98

3. General material selection and descriptions O O O O O O O CH2 CH2 O O CH2 CH2 O O C C O CH CH CH CH O C C O CH3 O CH2 CH O O CH2 CH O CH3 UP UNSATURATED POLYESTER RESINS are produced in two steps. First, unsaturated linear polyester resins are produced by polycondensation of unsaturated dicar- boxylic acids or their anhydrides with diols. These are then cross-linked in the second step with vinyl-containing monomers such as styrene or methacrylic acid methyl ester in radical copolymerization. The thermal resistance depends on the monomers used and is higher the more aromatic monomers are used. UP is char- acterized by good resistance to hydro- carbons, but is susceptible to hydrolysis. Unsaturated polyester resins are inex- pensive and often show lower shrinkage UP 0° 0° +/- good electrical Insulation – + –200° +185° low + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY MECHANICAL PROPERTIES and better dimensional stability due to lower water absorption. UP resins are used to make heating oil tanks and pipes, as well as furniture, car body parts, caravans and molded parts with electrically insulating proper- ties such as distribution boxes, plug connectors and housings for household appliances. PROPERTIES y the thermal application range is high- ly dependent on grades: –270 °C to +100 °C; special grades up to +185 °C y cost-effective y resistant to mineral oil, benzene, greases and hydrocarbons y good insulation properties y suited for contact with food y good colorability y brittle, low elasticity y poor resistance to acids, bases, hot water, ketones and halogenated hydro carbons I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 99 X E D N I

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Materials and Process Engineering N O R[ O ] n HO HO HO HO N O R[ O ] n N O R O N HO HO N n OH HO N O R[ O ] n O R[ O ] n HO HO EP EPOXY RESINS are usually oligomeric di-glycidyl ethers of bisphenol A, which are functionalized by a reaction with epichlorohydrin with a different number of epoxy groups per molecular chain. The cross-linking of these epoxy groups is then carried out with amine hardeners. A distinction is made between cold curing (aliphatic amines) and hot curing (aro- matic amines), as the type of curing also determines the maximum application temperature. Epoxy resins are classified as duromers since their properties can be adjusted very variably. On the one hand, many dif- ferent monomers and cross-linkers are available to create a specific structure. On the other hand, the functionality of the building blocks and therefore also the re- sulting cross-linking density can be con- trolled quite easily. PROPERTIES y thermal application range: –40 °C to +80 °C (cold curing), or +170 °C (hot curing), special grades up to +200 °C y wide range of properties y cold and hot cross-linking y suited for food contact y high elasticity (for duromers) N N EP +/- ﬂexible 0° – + –200° +170° medium + TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES This means that EP duromers can also be produced with comparatively high elas- ticities. The main applications of epoxy resins are components for electric motors, insulators and capacitors, paints and chemical- resistant floors. Rotor blades for wind tur- bines and helicopters as well as boat hulls are also made from EP resins. In addition, they are often the basis for printed circuits, pipelines, containers, pump components and adhesives for rubber-metal compos- ites. y good resistance to organic solvents, mineral oil, gasoline and water y low shrinkage, good heat resistance y low resistance to strong acids, bases and oxidizing agents 100

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3. General material selection and descriptions I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I OH PF –30° R O F S L A E S Y R A T O R S N O T A C I I L P P A +/- abrasion-resistant 0° – + +250° high + R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H n TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES PF PHENOL-FORMALDEHYD E RESINS The reaction of phenol with formaldehyde produces resinous condensation products. A distinction is made between Novolake (amine-cross-linking) and Resole (self-cross- linking). DIN-typed compounds differ in terms of various fillers and reinforcing agents and their contents. Like all duromers, phenolic resins have high hard- ness and strength and are flame-retardant. In addition to their good media resistance, phenolic resins also have high abrasion re- sistance. The continuous operating tem- perature can be up to +250 °C. Tempered parts can even be exposed to temperatures of up to +300 °C for short periods. PROPERTIES y thermal application range: –30 °C to +250 °C y high hardness and strength y low creep tendency y flame-retardant y high pressure resistance y yellow to brown coloration, darkening in use (light, heat) PF resins are used to make sockets, switch housings, lamp sockets, bearings and pump parts. They are also suited for manu facturing all kinds of handles, e.g. for pots and pans, irons and barbecues; as well as for billiard balls, gear wheels, binders for brake disk friction linings and as an adhesive agent in the manufacture of rubber-metal composites. In the field of sealing technology, PF resins are used in tribologically challenging applications, such as gearbox thrust washers, piston rings for hydraulic seals and other wear protection rings, as well as seals for intake manifolds or in brake cylinders. y brittle, notch-sensitive y not for contact with food y resistant to organic solvents, acids, alkaline and salt solutions y low elasticity and tensile strength y not resistant to strong acids and bases R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 101 X E D N I

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Materials and Process Engineering PI +/- low friction 0° – + –270° +260° high n TEMPERATURE RANGE (°C) MEDIA COMPATIBILITY DYNAMIC PROPERTIES and the radiation resistance of polyimides are excellent. The materials are largely resistant to solvents, greases, fuels, oils and acids. Only strong bases can attack polyimides. Polyimides are used to manufacture en- gine and compressor parts, aircraft parts, high-quality cable and wire sheathing, circuit boards and valve seats as well as fibers for fireproof protective suits. In sealing technology, the focus is on tri- bological applications: gearbox thrust washers, sealing applications for the aerospace industry, piston rings and other wear protection rings. y flame-retardant y strong bases can attack polyimides y high price y very hard and brittle O N O O N O O PI POLYIMIDES The starting materials for polyimides are bismaleimide or other tetracarboxylic acid anhydrides. From these, duromeric polyimides with different molecular structures are formed by poly- condensation with diamines. A common feature of these heterocyclic polymers is the very stable imide ring within the main chain. Polyimide components are charac- terized by high temperature resistance up to over +260 °C, in the short term also up to over +300 °C, while largely retaining their mechanical properties. The materials are also characterized by good sliding and wear properties, which can be further improved by adding appro- priate additives. The electrical properties PROPERTIES y thermal application range: –270 °C to +260 °C (briefly above +300 °C) y high hardness and strength y good sliding and wear properties y very resistant to solvents, greases, fuels, oils and acids y high radiation resistance 102

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3. General material selection and descriptions I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I In addition, Freudenberg's internal safety standards, which often go far beyond the legal requirements, particularly in the area of environmental protection and occupational safety, encourage the development teams to find ever more sustainable solutions. In particular, the use of raw materials in our formulations that are harmful to health or potentially hazardous to the environment is subject to strict internal safety standards. The continuous adaptation and further development of our materials portfolio is only possible under three conditions: y a large team of well-trained and expe- rienced materials developers and pro- cess engineers y in-house laboratories with comprehen- sive testing expertise y well-equipped pilot plants for constant monitoring and optimization of the processing behavior of the materials 3.9 COMPOSITION OF FST MATERIAL DESIGNATIONS Freudenberg Sealing Technologies uses standardized material designations for its elastic materials. 70 75 EPD M FKM 120209 585 Hardness (Shore A) Rubber designation Mixture number y Hardness: The prefix indicates the hardness of the material in Shore A y Rubber designation: The base rubber according to standard ISO 1629:1995 is named in second place y Mixture number: The number after the rubber designation is an internal FST code that can contain 3 to 6 digits and codes the formulation 3.10 VARIETY OF MATERIALS As a global market and technology leader in sealing technology, FST serves the needs of its customers with a portfolio of over 1,300 different materials made from 1,000 different raw materials. Every year, newly developed formulations are added to the portfolio, while out- dated formulations are abandoned. Our continuous efforts at product devel- opment serve and respond to the constant- ly growing demands of our customers, the ever more stringent requirements of chemicals legislation and the changing availability of raw materials. R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P Map-Marker-Exclamation Adaptation and further development of materials S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 103 X E D N I

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Materials and Process Engineering 4. UNDERSTANDING ELASTOMER FORMULATIONS Everything starts with the formulation – whether it’s a standard elastomer for a wide range of applications or specially designed compounds. This chapter exam- ines in detail the raw materials used and which properties of an elastomer they influence. FORMULATION INGREDIENTS The rubber industry uses a variety of raw materials that differ significantly in terms of their composition: rubber in bale, chip or pellet form is used along with other solids – usually in the form of powders, granules or pellets – and liquids. As confusing as a formulation may seem at first glance, its ingredients can be summarized into seven main groups of raw materials. Raw material rebbuR 1 relliF 2 relliF rezicitsalP Processing aid Anti-ageing agent 1 Anti-ageing agent 2 Vulcanization media ruhpluS rotareleccA Co-accelerator Activator zinc oxide Activator stearic acid Vulcanization retarder tnemgiP Total phr 001 03 51 01 1.5 2 2 1 3 1.5 4 2 1 3 176 Weight % 28.65 50.71 25.8 86.5 0.85 1.14 1.14 75.0 07.1 0.85 2.27 1.14 0.57 07.1 100 Fig. 10 Example of a rubber compound with sulphur cross-linking 104 7 Raw material groups of a formulation 1. Rubber 2. Fillers 3. Plasticizers 4. Anti-ageing agents 5. Processing aids 6. Vulcanization media • Cross-linkers • Accelerators • Activators • Retarders • Coagents 7. Special additives When selecting the raw materials for a rub- ber compound, it is important to consider not only the desired final properties of the elastomer but also the storage stability of the compound and its processability. Not every formulation necessarily contains all seven raw material groups. The quantities of raw materials used in a formulation are specified in the unit phr (=parts per hundred rubber). Phr denotes the mass fractions of theindividual raw materials in the formulation. They are always specified in terms of 100 parts by the mass of rubber. The advantage of the phr unit compared to a quantity in percent by weight is that the differences between formulations can be recognized at a glance when com- paring them. → Fig. 10 shows a general example of a formulation.

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4. Understanding Elastomer Formulations Different raw materials are used in very different quantities. The variety of raw materials used, the different proportions in the formulation and their different physical delivery forms place high demands on the mixing technology (see also → “7.2 Mixture production”, page 126). RUBBER The most important properties of an elastic material are its temperature limits and chemical resistance: both are largely determined by the rubber. The other properties can be varied in many ways through the appropriate selection and clever combination of all other com- pound components and can be tailored to the respective application. The following general questions should be asked in order to find the most suitable rubber for the application: y what media does the material come into contact with? y in what temperature range is the material used? y what are the ambient conditions? These can be varied – from direct sun- light to pressure and sea air y what mechanical stresses does the material experience? Strong defor- mation, dynamic stress or stress due to wear The most important rubber classes and their property profiles are described in → “3.3 All-purpose Rubbers”, page 50, und “3.4 Speciality Rubbers”, page 54. FILLERS Fillers are solid, usually particulate, some- times also platelet or fibrous solids in the size range between 10 nm and 500 µm. Contrary to what the word "filler" sug- gests, this class of material is not usually used to increase the volume of the com- pound at low cost. Rather, the targeted use of fillers can influence and optimize important properties of an elastomer such as hardness, stiffness, tensile strength and tear resistance, maximum elongation or wear. Special fillers are also used to influence the thermal or electrical conductivity or the fire behavior of elastomers, or to make the materials magnetic or magnetizable. The vast majority of rubbers do not ex- hibit sufficient tear and tensile strength if fillers are not used. Common filler classes used to reinforce elastomers are carbon blacks, mineral fillers such as chalk, silica, kaolin and talc as well as synthetic silicic acids and a range of metal oxides, sulphates and hydrox- ides. More and more fillers such as cellu- loses, lignins or carbon blacks obtained from used tires are now also being put to use. MEDIA STRESS Fillers are mainly described based on the following parameters: TEMPERATURE ENVIRONMENT y specific surface area y geometric structure y chemical nature of the surface I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 105 X E D N I

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Materials and Process Engineering Depending on the particle size and there- fore the specific surface area, a distinction is made between active (reinforcing) and in- active (non-reinforcing) fillers. The particle diameters of reinforcing fillers are between 10 and 100 nm, while inactive fillers have particle diameters between 500 and 1000 nm. In any case, the prerequisite for optimal properties of the rubber compounds is the most uniform possible distribution of the fillers as well as good dispersion (see also → “7.2 Mixture production”, page 126). Reinforcing fillers interact strongly with the rubber matrix. As a result, this filler class significantly influences the properties of the rubber compound and the vulcanizate. Reinforcing fillers increase the viscosity of the rubber compounds and the hard- ness of the vulcanizates. They improve the strength and abrasion behavior of the vulcanizates. There is an optimal filler dosage for each of these properties, i.e. these properties deteriorate again with high filler quantities. → Fig. 11 shows that certain properties cannot be opti- mized independently of each other. Inactive fillers have little or no reinforcing effect. In order to understand how the reinforcing effect of fillers (FS) in rubbers (R) works, four forces must be considered, which are of very different magnitudes and interact with each other: Internal cohesion of the FS particles >> Adsorption forces FS – R > Interaction forces R – R > Interaction forces FS particles – FS particles The rubber molecules attach to the sur- face of the filler particles during the mix- ing process (→ Fig. 12). The resulting adsorption forces contribute to the strength, which initially increases as the filler content rises. If a certain degree of filling is exceeded, there are no longer enough rubber molecules to adhere to the filler particles, and direct contact between filler particles increasingly occurs. As these interaction forces are much lower than those between rubber molecules and filler particles, the strength decreases again at high filler dosages. Properties such as viscosity or hardness, on the other hand, increase steadily as the amount of filler increases. This is due to the fact that solid particles are many times y t i s o c s V i s s e n d r a H i e c n a t s s e r r a e T i n o s a r b A Filler quantity Filler quantity Filler quantity Filler quantity reinforcing inactive Fig. 11 Influence of active and inactive fillers in elastomers 106

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4. Understanding Elastomer Formulations Fillers whose surfaces are designed to chemically bind to the rubber molecules during vulcanization enable special prop- erty profiles of the rubber compounds: above all, a good combination of strength, abrasion, wear and elasticity. Map-marker-edit Special property profiles of the rubber compounds I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P PLASTICIZERS Plasticizers are liquids, greases or resins that are added to rubber mixtures for various reasons. There are advantages both in the processing of the rubber mixture and in the properties of the vulcanizate. y As a processing aid Plasticizers reduce the viscosity of the mixture and make the rubber com- pounds easier to process y To increase the filling level The use of plasticizers enables high filler dosages. Rubber compounds with large quantities of fillers are very viscous and therefore usually difficult to mix and pro- cess. The addition of plasticizers lowers the viscosity and allows the use of larger quantities of fillers while maintaining good filler distribution and dispersion. y To reduce the stiffness and hardness of the vulcanizate As the word "plasticizer" suggests, plasticizers reduce hardness and stiff- ness; at the same time, they increase the elongation of the vulcanizate H O H O Si Si Si Si SiSi H H O O CH3 CH3 Si CH3 O H O Si Si Si Si SiSi S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B CH3 Si O O CH3 S M G A R H P A D I X O B G N I F F U T S I S G N K C A P O H O H O H O CH3 Si CH3 CH3 Fig. 13 Hydrophilic and modified hydrophobic silica surface 107 X E D N I Fig. 12 Polymer chains attached to a filler particle stiffer than rubbers. The higher their pro- portion in the rubber, the more viscous the mixture becomes and the stiffer and hard- er the vulcanizate becomes. The chemical nature of the surface of fill- er particles also has a major influence on the mixing properties. It determines how well the filler particles can be mixed into a rubber and how strong the adsorption forces are between the rubber molecules and filler particles. Fillers with a strongly polar, hydrophilic (water-loving) surface such as silicic acids are more compatible with polar rubbers and tend to be more difficult to mix in be- cause the interaction forces between FS particles and FS particles are very high. High strengths can be achieved with such fillers, but the elastic recovery behavior is often not optimal. Fillers with a non-polar, hydrophobic (water dissimilar) surface such as carbon blacks or chemically modified (hydropho- bized) silicas exhibit weaker interaction forces between the FS particles. They are therefore easier to mix in, have less influ- ence on the viscosity of the mixture and enable materials with high elasticity.

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Materials and Process Engineering Fig. 14 Rubber matrix with filler particles (left) and mixed-in primary plasticizer (right) y To improve low-temperature flexibility By adding appropriate plasticizers, the glass transition temperature of the vul- canizate can be lowered and thus the minimum application temperature can be shifted to lower temperatures The addition of plasticizers causes various properties of a vulcanizate to change simul- taneously. For example, plasticizers can be used to improve flexibility at low tempera- tures, but this often also leads to a deteri- oration in resistance to hot air. The mode of action of plasticizers can be divided into two groups: y Primary plasticizers (→ Fig. 14) This type of plasticizer is very similar in its molecular structure to the rubber used, which is why the plasticizer mixes very well with the rubber. Individual plasticizer molecules attach them- selves to the polymer chains, which considerably improves the mobility of the polymer chains. This results in a significant reduction in the viscosity of the mixture as well as improved low-temperature flexibility and re- duced stiffness The combination of EPD M with paraffinic mineral oils is one example. The rubber and plasticizer molecules differ considerably in size. However, they are chemically very similar and can therefore be easily mixed with each other y Secondary plasticizers (→ Fig. 15) This type of plasticizer differs so much in terms of its chemical structure and polarity from rubber that it mixes with the rubber only with difficulty and therefore cannot be absorbed by the rubber matrix, or only in small quanti- ties. Secondary plasticizers act like inter- nal lubricants. They have hardly any in- fluence on the viscosity, tend to sweat out due to their low rubber compatibil- ity. This effect depends on time and temperature: After the compound has cooled down, the plasticizer may sweat out, as the amount of secondary plasti- cizer that the rubber compound can ab- sorb decreases rapidly as the tempera- ture drops. This effect can significantly facilitate the demolding of the vulcani- zate from the mold One example is the use of paraffinic mineral oils in oil-resistant NBR rubbers The most common plasticizers can be found in the following list: 108

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4. Understanding Elastomer Formulations MINERAL OIL PLASTICIZERS (CRUDE OIL REFINING) NATURAL SUBSTANCES AND MODIFIED NATURAL SUBSTANCES SYNTHETIC PLASTICIZERS y paraffinic y naphthenic y aromatic y highly aromatic y fatty acids y fatty acid esters y wool grease (lanolin) y vegetable oils y resins y factice y Ester plasticizer y Ether plasticizer y Thioether ester y Polyether, Polythioether y Polyester y Chlorinated hydrocarbons PROCESSING AIDS Processing aids are a class of chemicals that are added to rubber compounds in small quantities to improve processability. Their use is often closely linked to a special pro- cessing or molding process. In addition to improving the flow behavior or wall slip, processing aids are also used to reduce or increase the stickiness of the raw com- pounds and to improve demolding. Processing aids that improve the flow behavior act similarly to secondary plas- ticizers, but their lubricating effect is par- ticularly pronounced. Even at a very low proportion in the compound, they ensure that the rubber chains slide against each other, which often significantly improves not only the flow but also the demolding behavior of the compound. These chem- icals are used when rubber compounds need to flow very well, especially when molding in the injection molding process. Processes with long flow paths, filigree distributors and those in which the tem- peratures remain low during flow, such as in cold runner technology, place particu- lar demands on the flow behavior (see also → “7.3 Shaping and vulcanization”, page 130). ANTI-AGEING AGENTS The rubbers used in the rubber industry are organic molecules that essentially consist of the atoms carbon, hydrogen, oxygen and nitrogen. Some rubbers also contain silicon, chlorine or fluorine atoms and in some cases, sul- phur is also added during vulcanization. The chemical bonds between these atoms vary in terms of stability, with the least stable bond determining the life of the vulcanizate. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P Fig. 15 Rubber matrix with filler particles (left) and an attached secondary plasticizer (right) 109 X E D N I

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Materials and Process Engineering Rubber molecules age at different rates and to different degrees; the least resist- ant to ageing are R-rubbers with many double bonds and sulphur-cross-linked vulcanizates. The maximum application temperatures shown in → Fig. 16 provide an initial indication of the ageing resist- ance. The shaded areas indicate temper- ature ranges to which standard grades can only be exposed for a short time or that can only be reached by special grades. The term “ageing” covers a large number of physical and chemical processes that irre versibly change the material proper- ties and which occur under the influence of oxygen, ozone, UV light, temperature, hot water, steam, acids, alkalis or other media as well as under mechanical stress. Ageing can have different effects on dif- ferent elas tomers: Ageing effects depend on the type of change in the polymer network and can be divided into three groups: y chain dismantling y reduction of cross-linking points y additional cross-linking As shown schematically in → Fig. 17, age- ing can lead to a breakdown of polymer chains or cross-linking points. As a result, hardness, stiffness and elasticity decrease and elongation increases. On the other hand, ageing can also gen- erate additional cross-linking points; in this case, hardness, stiffness and elastic- ity increase, while elongation decreases significantly. The mechanisms of ageing are complex and in many cases not fully understood. Several effects often overlap. Ageing vulcanizates can first soften and then harden and become brittle after pro- longed ageing or at higher temperatures. The higher the application temperatures, the faster the vulcanizates age. As a first rule, one can say that an increase in tem- perature by +10 °C accelerates ageing by a factor of 2 (Arrhenius law). The ageing of organic materials cannot be prevented, but it can be significantly delayed by using the right chemicals (anti- ageing agents). The anti-ageing agents are used up over time and their protective effect diminishes. Two modes of action of anti-ageing agents are explained briefly below: y Surface protection Paraffin waxes have the property of migrating to the surface of the vulcan- izate and forming a protective film there. Paraffins are hydrocarbons without double bonds and effectively protect rubber from ozone attack. In particular, rubbers with double bonds in the main chain benefit from this built-in “sun cream” protection. y Protection against ageing due to oxygen and heat (thermo-oxidative ageing) Oxygen is one of the media that can attack and destroy rubber molecules. When oxygen reacts with a rubber molecule, highly reactive radicals are formed that can attack and damage other molecules in a chain reaction. To prevent this, anti-ageing agents are added, which are attacked instead of the polymer network and thus inter- cept the radical attack. 110

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4. Understanding Elastomer Formulations s r e b b u R AU FFKM PVMQ FVMQ VMQ FKM AEM ACM HNBR ECO IIR/CIIR NBR EPDM CR SBR NR –100 –50 0 +50 +100 +150 +200 +250 +300 Temperature [°C] Fig. 16 Temperature application limits of the most important rubbers The use of anti-ageing agents must be adapted to the base rubber, the other components of the formulation and the subsequent use of the elastomer. For the best possible protection, two or three anti-ageing agents are often combined to provide a synergistic effect, especially in the case of R rubbers that are not highly resistant to ageing. CROSS-LINKING SYSTEM The topic of cross-linking is covered in detail in → “5. Cross-linking chemistry”, page 114. Therefore, the most impor- tant substance classes that belong to the most common cross-linking systems are described only briefly below. Cross-linking agents Cross-linking agents are chemicals that form covalent bonds, so-called cross- linking bridges, between the individual rubber molecules. These include elemental sulphur, sulphur donors and peroxides. Accelerators Sulphur alone only reacts very slowly with the rubber molecules, even at high temperatures. Although vulcanization with pure sulphur at +150 °C takes sever- al hours, the cross-linking remains incom- plete and the elastomers produced in this way have only a moderate property pro- file and age quickly. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 111 X E D N I

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Materials and Process Engineering Cross-linked polymer chains + Attacking medium (e.g. oxygen, oil, water, ozone, UV light ...) Chain degradation (loss of tension) Additional cross-linking (increase in tension) Reduction of cross-linking points (loss of tension) Polymer molecule (rubber molecule) Cross-linking points Fig. 17 Aging of elastomers Accelerator chemicals are added to reduce reaction times, temperatures and the amount of sulphur required. Common rep- resentatives of this substance class are or- ganic compounds that contain nitrogen or sulphur, such as benzothiazoles, benzothi- azole sulfenic amides, dithiocarbamates, guanidines or amines, which are used in- dividually or in combination. Activators Metal oxides and fatty acids are used to improve the effectiveness of the acceler- ators. The most common is the combina- tion of zinc oxide and stearic acid. Vulcanization retarders Retarders are sometimes used in sulphur- based vulcanization systems, especially for thick-walled components or in manu- facturing processes with long flow paths. These chemicals delay the vulcanization, i.e. they extend the time until the start of the cross-linking reaction (scorch time) without significantly affecting the over- all speed of the reaction. Organic acids such as benzoic acid, salicylic acid and phthalic anhydride are often used, which have a retarding effect by lowering the p H value. Coagencia If rubber compounds are peroxide cross- linked, coagents are often used in addition to the peroxide cross-linking agent. These chemicals increase the cross-linking den- sity, and some members of the substance class additionally accelerate vulcanization. The use of coagents often allows the amount of peroxide used to be reduced and the vulcanizates exhibit higher elasticity. Coagents have at least 2 active double bonds, typical representatives are triallyl- cyanurate, trialyl isocyanurate, di- or tri- functional acrylates and methacrylates as well as short-chain 1.2-polybutadienes. 112

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4. Understanding Elastomer Formulations ADDITIONAL ADDITIVES Other chemicals can be used in special applications. y Color pigments if colored elastomers are needed, light-colored fillers are used and appro- priate color pigments are mixed in y Blowing agents for the production of foamed rubber or sponge rubber, blowing agents tailored to the respective cross-linking system are added to the rubber mixtures, which release a gas during vulcanization that produces the foam structures y Fire protection additives most rubbers are flammable. For fire protection applications, special addi- tives are therefore mixed into the rub- ber compounds so that the elastomer self-extinguishes even in direct contact with a flame, i.e. neither continues to burn nor afterglow I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 113 X E D N I

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Materials and Process Engineering 5. CROSS-LINKING CHEMISTRY Anyone familiar with the history of rubber knows that the decisive step was not taken until 1839 with the discovery of vulcanization by Charles Goodyear. Be- fore that, natural rubber was certainly a useful material in many respects, but its properties had little in common with those of a vulcanized elastomer. Unvulcanized rubber compounds are plastically deformable and flow under pressure. It is only through the chemical reactions that take place during vulcani- zation that a rubber compound becomes a cross-linked elastomer with high dimen- sional stability and elastic properties. unvulcanized vulcanized rubber Fig. 18 Cross-linking points due to vulcan- ization As can be seen in → Fig. 19, uncured rubber compounds also exhibit elastic material behavior to a small extent, al- though the plastic component always clearly predominates. In the same way, vulcanized rubbers, which behave mainly elastically, also show plastic material be- havior to a small extent, depending on the degree of cross-linking, the polymer and the rest of the formulation. Modern manufacturing processes require close coordination between the formula- tion and the manufacturing process. The composition of the compound and, in particular, the type and quantity of cross-linking chemicals must be selected in such a way that the rubber article can be reliably produced in the selected manufacturing process and has the de- sired end properties. CROSS-LINKING DENSITY The number of chemical bonds formed between the polymer chains during rub- ber, but primarily depends on the amount of cross-linking chemicals used and is called the degree of cross-linking or cross-linking density. before with deformation after deformation before with deformation after deformation unvulcanized rubber vulcanized rubber Fig. 19 Behavior during deformation (difference between unvulcanized and vulcanized rubber) 114

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s e i t r e p o r p Tear propagation Fatigue i t e a z n a c u V l 5. Cross-linking chemistry Elasticity Hardness Stiffness (modulus of elasticity) Tensile strength Hysteresis, damping Permanent deformation Coefficient of friction Elongation at break Cross-linking density Fig. 20 Influence of cross-link density on elastomer properties The cross-linking density also depends on the temperature and the duration of vulcanization and has a major impact on the material properties (→ Fig. 20). Stiff- ness (modulus of elasticity), hardness and elasticity increasing cross-linking density, while elongation at break, damping and permanent defor- mation decrease. Tear propagation resist- ance and tensile strength each reach a maximum. increase with As can be seen from → Fig. 20, it is not possible to achieve an optimal result for all material properties by selecting a specific cross-linking density. The degree of cross-linking is always selected in such a way that the best possible compromise of physical properties is achieved for the respective application. CROSS-LINKING CHARACTERISTICS The course of the cross-linking reaction can be determined using vulcometry. In a special rheometer, the change in the stiff- ness of a rubber compound is measured over time at a constant temperature. The sample is oscillated between two plates at a fixed frequency and the change in torque, which is proportional to the degree of cross-linking, is recorded as a function of time. Typical vulcameter curves are shown schematically in → Fig. 21. There are three characteristic segments of the curve (→ Fig. 21) 1. The flow period covers the time interval from the start of the measurement to the start of cross-linking, i.e. until the torque increases. It characterizes the range of viscous flow. Initially, the torque decreases due to the heating of the rubber compound. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 115 X E D N I

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Materials and Process Engineering The period until the cross-linking reac- tion starts is known as the incubation time. During this time, the mold filling of the tool must be completed. 2. The torque increases significantly during the cross-linking period. This time is re- quired to convert the rubber compound into the optimal cross-linked state. The slope of the curve depends heavily on the type of rubber and the cross-linking chemicals used. 3. Cross-linking is complete when the torque has reached its final value. All chemical reactions are now complete. Curves are also sometimes observed in which the torque reaches a maximum and then decreases again (reversion) or where the torque continues to increase steadily (marching modulus). Every rubber compound shows its own typical curve; the vulcameter curve thus represents a kind of fingerprint of the cross-linking behavior of each rubber compound. The appropriate choice of cross-linking chemicals is used to adjust the cross-linking characteristics of a rubber compound and adapt it to the processing method. This ensures the quality and eco- nomic manufacturability of the rubber components. In addition to development of the formu- lation, vulcanization tests are mainly used for incoming goods inspection and for release testing of rubber compounds. Flow period Cross-linking period T = const ] m N [ e u q r o T 1,0 0,8 0,6 0,4 0,2 0 0 1 2 3 4 5 6 Time [min] Fig. 21 Typical volcameter curves for measuring the cross-linking process 116

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5. Cross-linking chemistry OPTIMIZATION OF ELASTOMER PROCESSING For robust process control to produce flawless rubber articles with as little waste as possible, the flow behavior of the rubber compound must be taken into account in addition to the cross-linking characteristics (cross-linking kinetics). This is because it is not only knowledge of the speed of the cross-linking reaction that is of importance in the molding process, but also how quickly the mold can be filled. In the end, both properties – flow behav- iour and cross-linking characteristics – to- gether significantly determine the overall cycle time, i.e. the time in which the mold can be filled, the rubber compound vulcan- ized and the finished component removed from the mold. The targeted coordination of both parameters with each other and with the manufacturing process allows both material savings by reducing waste and energy savings through shorter heat- ing times and thus a cost-effective produc- tion of the elastomer molded part. The complex relationships between mold filling and vulcanization can be calculat- ed and optimized with the help of filling simulation. Even during the development phase of a rubber compound for a specific application, flow velocities and tempera- ture distributions can be simulated on the computer and the influences quantified. Processing errors such as air inclusions or premature scorching are thus detected at an early stage and avoided by adjust- ing the composition of the formulation or the processing procedure. This reduces the development effort con- siderably. COMPATIBILITY OF THE CROSS-LINKING CHEMICALS It should be noted that not every type of rubber can be vulcanized with every type of cross-linking chemistry. For example, cross-linking with sulphur only works with rubbers that contain double bonds. The active sites for sulphur cross-linking are the hydrogen atoms on the carbon atom next to the double bond, the hydrogen atoms in the allylic position. Some types of cross-linking can only be used if the rubber molecules contain special functional groups. These are al- ready created during the synthesis of the rubber by polymerization of special cure- site monomers. CROSS-LINKING AGENTS The cross-linking system determines the processing behavior of the rubber com- pound as well as the chemical structure of the polymer network and thus the physical properties of the elastomers. Many classes of rubber can be cross-linked in several ways. The manufacturing process and the desired property profile of the elastomer compo- nent must be taken into account when se- lecting the best suited cross-linking system. The two most common types of cross-link- ing are cross-linking with sulphur and with peroxides, both of which are described in more detail in the following chapters. Sulphur cross-linking is primarily used in the class of diene rubbers. (R rubbers) are used, and peroxides can also be used to cross-link rubbers without double bonds. There are also various other types of rubber cross-linking, most of which have been developed specifically for certain classes of rubber. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 117 X E D N I

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Materials and Process Engineering The cross-linking points in vulcanized elastomers are usually 30 to 100 monomer units apart. An overview of the possible types of cross-linking chemistry of the most com- mon rubbers can be found in → Tab. 5, page 122. 5.1 CROSS-LINKING WITH SULFUR Elemental sulphur or sulphur donors are used for sulphur cross-linking. Sulphur donors are molecules that release sulphur at high temperatures. Cross-link node structures As already mentioned, cross-linking with sulphur works with all rubber classes that have a sufficient number of C=C double bonds and whose structures have hydro- gen atoms on the carbon atom next to the double bond, so-called allylic hydrogen atoms. S S S S S S S S8 ring S Ring opening S S S S S S S S S S S SX Fig. 22 Types of sulphur bridges in sulphur cross-linking: mono-, di- and polysulphidic 118 TYPE OF BINDING C-S binding S-S binding S-S-Sx binding C-C binding BINDING ENERGY [kJ/mol] 285 268 < 268 356 Tab. 3 Binding energies at a glance When cross-linking with sulphur, the rubber molecules are chemically linked by sulphur bridges. These can form in different ways; depending on the cross-linking system used, cross-link node structures are formed from just one sulphur atom (monosulphidic sulphur bridges, S1), from two sulphur atoms (disulphidic, S2) or from more than two sulphur atoms (poly sulphidic, S-S-Sx). Properties of the cross-link nodes Monosulphidic bridges have the highest binding energy of the three types of sul- phur bridges and are therefore the most stable, while polysulphidic bridges have the lowest binding energy. Sulphur bridges are always less stable than bonds between two carbon atoms (→ Tab. 3). Elastomers with predominantly mono- and disulfide structures exhibit less per- manent deformation, better thermal re- sistance and are less prone to reversion than elastomers with a high proportion of polysulfide bridges. In contrast, elastomers with predominant- ly polysulphide structures are more resist- ant to fatigue. This is due to the fact that poly-sulphide cross-linking sites can mi- grate along the polymer chain at elevated

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5. Cross-linking chemistry Rubber elasticity Leathery condition Steel elasticity I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A 0.25 … 7 phr sulphur 7 … 25 phr sulphur 25 … 40 phr sulphur R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P y t i c i t s a E l Degree of cross-linking Fig. 23 Influence of the sulphur content on the material properties S L A E S C I T A T S There are no clear boundaries between the cross-linking systems. The amount of sulphur used not only in- fluences the type of sulphur bridges, but also the number of cross-linking points. If the usual sulphur content in the rubber compound is a few percent by weight, it is referred to as soft rubber, while very high sulphur contents of over 25 percent by weight are referred to as hard rubber. temperatures without causing chain scis- sion. This leads to a certain self-healing effect, local stress peaks can be reduced and early failure under dynamic load is avoided. Cross-linking systems Which type of linkage is created depends heavily on the amount of sulphur used. At higher sulphur levels, predominantly S-S-Sx compounds are formed; in low-sul- phur systems, S2 bridges tend to form. Sul- fur donor systems predominantly produce S and S2 bridges. In addition to sulphur and/or sulphur donors and activators such as zinc oxide and stearic acid, a sulphur crosslinking system also contains one or more accelerators. The ratio of accelerator to sulphur char- acterizes the cross-linking system. A low ratio is called a "Conventional Vulcaniza- tion System" or CV system; a high accel- erator: the sulphur ratio is referred to as an "Efficient Vulcanization System" or EV system. The "Semi-efficient Vulcaniza- tion System" or SEV system lies between the "Conventional" and the "Efficient Vul- canization System" (→ Tab. 4). CROSS-LINKING SYSTEM Conventional Vulcanization (CV) Semi-efficient Vulcanization (SEV) Efficient Vulcanization (EV) SULPHUR ACCELERATOR RATIO S-S-SX BRIDGES S1 BRIDGES [phr] [phr] ACCEL. : SULPHIR 2.0 … 3.5 0.4 … 1.2 0.1 … 0.6 1.0 … 1.7 1.2 … 2.5 0.7 … 2.5 0.4 … 0.8 2.0 … 5.0 2.5 … 12.0 [%] 95 50 20 [%] 5 50 80 Tab. 4 Sulphur cross-linking systems G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 119 X E D N I

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Materials and Process Engineering At medium sulphur doses, leather-like materials are obtained that have no useful properties. Typical products made of hard rubber in- clude ice hockey pucks, mouthpieces for woodwind instruments such as the clari- net or saxophone and high-quality combs. 5.2 CROSS-LINKING WITH PEROXIDES Peroxide cross-linking is a radial cross-link- ing process in which coagents are often used in addition to the peroxides. Peroxides are usually used that decompose within a few minutes in the temperature range of +150 to +220 °C and form active radicals. In a subsequent step, these radi- cals react with the main chain of the rubber and transfer the radical function to the rubber molecule. The linking of two such polymer radicals provides a cross-link node. The two chains are linked directly via a thermally very stable C-C bond (→ Fig. 24). The use of coagents, also known as coac- tivators, can increase the efficiency of the crosslinking reaction: the cross-linking density increases and some coagents ad- ditionally accelerate the vulcanization. Their use makes it possible to reduce the amount of peroxide used and the vulcan- izates exhibit higher elasticity. Coagents have at least 2 active double bonds that tend to form radicals; typical representatives include triallyl cyanurate, triallyl isocyanurate, di- or tri-functional acrylates and methacrylates as well as short-chain 1.2 polybutadienes. The use of coagents changes the cross-link node structure of the radical crosslinking: the polymer radicals formed in the first step now react with the coagent molecule and transfer the radical function to the polymer. A single radical transfer then results in several crosslinking-effective subsequent reactions. The coagence mol- ecule acts as a bridging molecule and in- creases the distance between the bridged rubber chains (→ Fig. 25). The formation of radicals requires higher temperatures during vulcanization than is the case with sulphur cross-linking. A re- arrangement of the formed cross-linking bridges is not possible here. Decomposition of the peroxide → Radical formation R O O R Peroxide Temperature 2 R O● Radical Transfer of the radical on the polymer chain R O● H ● R OH Recombination → Networking point ● ● Fig. 24 Reaction mechanism of peroxide cross-linking 120

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5. Cross-linking chemistry Polymer chain Polymer chain O N N O N O Fig. 25 Peroxide crosslinking: cross-link node with coagent triallylcyanurate (TAC) Polymer chain There are also peroxide-crosslinked mate- rials that do not benefit from a tempering step or where post-heating is not possible due to the manufacturing process (e.g. continuous production by extrusion) or component size. Excessive tempering leads to ageing and can damage the com- ponent. Compared to sulphur-crosslinked elasto- mers, peroxide-crosslinked elastomers are more heat-resistant and exhibit less permanent deformation (lower compres- sion set). The disadvantages of peroxide crosslinking are, in addition to the sensi- tivity to oxygen and the lower flexibility in the adjustment of the crosslinking characteristics, above all the lower tear resistance and a lower tear propagation resistance as well as poorer fatigue resist- ance under dynamic stress. Peroxide crosslinking is mainly used for elastomers with only a few or no double bonds in the main chain (→ Tab. 5). TEMPERING Peroxide-crosslinked molded parts are often tempered after vulcanization. In this process, the elastomer component is reheated at an elevated temperature in the oven for a certain period of time. The dwell time and temperature depend on the polymer and compound, and the thickness of the component also plays an important role. Common post-heating temperatures are between +150 °C and +220 °C, usual reheating times between 4 and 24 hours. Post-heating serves to optimize the com- ponent properties. The cross-linking re- action, which may not have fully taken place during vulcanization, is terminated. Volatile components and unwanted re- action products can escape from the ma- terial, which reduces the odor and im- proves some physical properties, especially strength and setting behavior. Tempering allows certain formulation components such as antioxidants or ozone protection agents to migrate to the component surface and develop their full effect there. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 121 X E D N I

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Materials and Process Engineering RUBBER SULPHUR PEROXIDE BISPHENOL DIAMINE METAL OXIDE PLATINUM RESIN NR IR BR SBR IIR XIIR CR NBR HNBR EPDM CM CSM EVM ACM AEM FKM VMQ/FVMQ ECO B B B B B B F B B B F F D D D D B B B B B B B B B B B B D D D B B B B B B B F F B B B F B = possible D = possible, but unusual F = special chemistry or special types Tab. 5 Types of crosslinking chemistry for the most common rubber classes 122

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6. CARRIER PARTS 6. Carrier parts I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I If rubber elasticity and high rigidity have to be realized in one component, elasto- mers are mechanically or chemically bonded to metal or plastic carriers. The carrier or stiffening element then gives the elastomer molded part the necessary dimensional stability. Suitable reinforc- ing elements are either made of metallic materials or thermoplastic or duromer plastics. Depending on the application, quenched and tempered steels as well as stainless and acid-resistant steels are used in ad- dition to unalloyed steels. Non-ferrous metals are also used, in particular non-ferrous metals such as copper, zinc, brass or bronze as well as light metal alu- minum alloys. In the field of plastics, technical or high- performance thermoplastics such as ali- phatic or partially aromatic polyamides, polybutylene terephthalate, poly-phe- nylene sulphide, polyether ether ketones and duromers are used. Extensive stiff- nesses are achieved here in particular by using glass or carbon fiber-reinforced grades. Examples: Unalloyed steels according to DIN EN 10139 y D C 01 (1.0330) Rust and acid-resistant steels in accordance with DIN EN ISO 3506 y 1.4301 (X 5 Cr Ni 1810) y 1.4404 (X2CrNiMo17-12-2) y 1.4571 (X 6 Cr Ni Mo Ti 17122) y 1.4112 (X 90 Cr Mo V 18) y 1.4542 (X 5 Cr Ni Cu Nb 174) R O F S L A E S Y R A T O R S N O T A C I I L P P A Fig. 26 Section through a single-layer system; scanning electron microscope image R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P Rubber Cement Pre-treatment Rubber Cover Primer Pre-treatment Metal Metal S L A E S C I T A T S Fig. 27 left: One-layer system (cement), right: two-layer system (primer + cover) Quenched and tempered steels according to DIN EN 10132 y 1.0501 (C35) y 1.0503 (C45) y 1.1191 (CK 45) Plastics y PA 6.6 GF30 y PPS GF30 y PEEK Today, the majority of all elastomer com- posite parts are produced with an insep- arable chemical bond that is created si- multaneously via the vulcanization of the elastomer in the molding tool under pres- sure and temperature. In some applica- tions, physical anchoring of the elastomer to the reinforcing part is sufficient to en- sure the function of the composite part. G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 123 X E D N I

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Materials and Process Engineering Both the design and manufacture of composite components, in which the bonding partners are chemically bonded, require some attention. DESIGN OF THE COMPOSITE COMPONENT y the rubber layer on the carrier part should be at least 0.5 mm so that the flow speed of the elastomer is kept as low as possible during the filling pro- cess. If the gaps are too narrow, there is a risk that the binder will be pushed off the carrier part by the nozzle effect, resulting in bonding and/or flow de- fects y if the carrier part is only to be partial- ly overmolded with elastomer, the carrier part must provide sufficient surface area for the imprint edges of the tool. If possible, the width of the impression surface should be at least 1 mm y in the case of fully encapsulated mold- ed parts, the carrier part must be centered in the tool using centring cams or pins. In addition, the bonding forces can be increased if undercuts or holes on the carrier part enable addi- tional mechanical anchoring of the elastomer y for tight tolerances or fits, the carrier parts should be large enough for any necessary finishing work y with thermoplastics in particular, care must be taken to ensure that the carrier parts are still dimensionally stable at vulcanization temperature so that they do not deform during the vulcanization process PRETREATMENT OF THE CARRIER PARTS In order to ensure good chemical bond- ing and thus a long service life of the composite component, appropriate surface treatment of the carrier parts is essential. y the carrier parts must be cleaned of adhering dirt and degreased. The sur- face is then enlarged and roughened using the following methods: • mechanical roughening: under the influence of a solid abrasive, e.g. sand, under pressure, impurities are removed from the surface and the surface is roughened • acid-cleaning: the reaction with acid is a cleaning step to remove unwanted metal oxides such as rust, corrosion and tarnish layers, which are usually associated with the base metal • phosphating: the chemical process of zinc or iron phosphating gives unalloyed steels a fine crystalline needle-shaped layer of metal phos- phates on the surface. The metal phosphate layer is firmly anchored in the metal surface, increases the sur- face area and provides protection against rust. It also enables the ap- plication and adhesion of binding agents y after surface pre-treatment and acti- vation, the binder system is applied. The aqueous or solvent-based binders are applied in one or more layers by brushing, spraying, tumbling or dipping onto the pre-treated carrier parts. The water or solvent used must then be completely removed. In many cases, the binder system must be baked in a subsequent step by heat treatment in an oven 124

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6. Carrier parts If the carrier part has a large volume and a large mass has to be heated during vulcanization of the rubber compound, it is advantageous to preheat the car- rier parts in prepared ovens y particularly in the injection molding process, there is a risk that the binder will be sheared off the carrier part by the high injection pressures of the rubber mixture and the chemical bonding will be faulty. The design of the injection molds should therefore provide for a right-angled arrangement of the injection nozzles to the carrier part y the process parameters (pressure, temperature, heating time) must be selected in such a way that not only the vulcanization of the rubber com- pound is largely completed when demolding, but also the chemical re- actions that must take place to form the bond between the elastomer and the carrier part have been completed y activated carrier parts treated with a binder must be stored properly. The environment must be dry and free of dust and grease. Temperatures that are too high or too low will impair the subsequent bonding of the elastomer, as will excessively long storage times for the pre-treated carrier parts y for the best possible bonding of the elastomer to the carrier part, the bonding agent system used must be matched to the rubber compound to be bonded and the material of the carrier part to be bonded. Water-based systems are preferable in terms of environmental and health protection, but are more challenging to use. The following three binder systems are commonly used. • phenolic resins with a hardener • polymer dispersions with a filler and a crosslinker • reactive silanes These systems are safe to work with and offer very good mechanical, thermal and chemical resistance of the elastomer composites after vulcanization. PRODUCTION OF THE ELASTOMER COMPOSITE COMPONENT y good chemical bonding of the rubber compound to the carrier part is only achieved if the total cycle time re- quired to heat up the carrier part in the vulcanization process is taken into account in the total cycle time. In par- ticular, if the carrier parts are placed cold in the hot shaping tool, the time required for heating up to temperature must be taken into account, otherwise the degree of cross-linking of the elastomer and the chemical bonding to the carrier part will be insufficient. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 125 X E D N I

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Materials and Process Engineering 7. FROM RAW MATERIAL TO FINISHED PART 7.1 PROCEDURE Various processing steps are necessary to produce the elastomer molded part from the many raw materials. Specialist knowl- edge and suitable machine technology are required in each individual process step so that rubber components can be manufactured economically and to a high quality. The most important processing steps are 1. Incoming inspection and weighing of the raw materials mixer and two downstream rolling mills, one for mixing and the second for mold- ing. This is usually followed by a batch-off unit, in which the mix in the form of con- tinuous skins or continuous strips is cooled to room temperature and in some cases provided with a release agent so that the skins and strips do not stick to- gether during storage of the finished mixtures. The mixing process in the internal mixer consists of the following four steps: 2. Production of the rubber compound 1. Shredding of the rubber supplied as including strainers bales 3. Production of a preform (blank) 4. Article production through shaping 2. Incorporation of fillers and plasticizers (incorporation) and vulcanization 3. Separation of the filler agglomerates 5 Reheating 6. Post-processing (deburring, grooving, washing, etc.) 7. Final inspection (dispersive mixing) 4. Distribution of the comminuted fillers in the rubber matrix (distributive mix- ing) Not all process steps are always run through to the finished article. For exam- ple, many rubber mixtures are not strained and some molding processes do not re- quire a special preform. Post-heating of elastomer components is only necessary for certain compounds and not necessar- ily for all applications. Not all items re- quire special post-processing either. 7.2 MIXTURE PRODUCTION In the mixing process, all raw materials are processed into a homogeneous rubber compound. A mixing line in a typical mixing plant for the production of rubber compounds consists of a kneading unit, the internal First, the raw rubber is prepared by crush- ing the raw bales and bringing them up to temperature using the high shear forces that occur in the internal mixer. The vis- cosity of the rubber is reduced, it be- comes flowable and can therefore absorb the other components of the mixture more easily. The next step is to add fillers and plasti- cizers, known as incorporation. The mix- ture is initially very inhomogeneous and has hardly any cohesion. Through further mixing, an externally homogeneous mass is gradually formed. The air, which is caught up between the filler particles is displaced and the empty spaces on the surfaces of the particles are filled with rubber. 126

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7. From raw material to finished part Once this process is complete, the mix- ture appears to be homogeneous. How- ever, there are still filler agglomerates in the mix at this point. These are broken up (divided) by the subsequent dispersive mixing, so that their volume decreases and their surface area increases. This is necessary in order to optimally wet the fillers with the rubber; this is the only way to achieve the reinforcing effect of the fillers in the subsequent product. At this stage, the other components of the formulation, such as anti-ageing agents, pigments, processing aids, acti- vators, coagents and possibly also crosslinking chemicals, are usually added. Finally, so-called distributive mixing achieves the optimal distribution of all raw materials in the rubber matrix. Only now is a completely homogeneous rub- ber mixture created. A size comparison of the individual com- ponents shows the great demands that the entire mixing process has to meet for the various components that must be mixed together as homogeneously as possible. Viewed in a proportion model, in which spaghetti illustrates the polymer molecules, the sizes range from 8 mm to 30 m (→ Fig. 28). Polymer ball Carbon black aggregate ZnO particles (detail) Proportion model: Spaghetti Length [nm] Diameter [nm] Particles Length Diameter [m] [m] 1,000 … 3,000 0.15 Rubber molecule 10 … 30 0.015 50 190 320 4 5,000 0.8 0.5 1.9 3.2 0.04 50 0.5 0.5 1.8 0.015 50 I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 50 50 Polymer ball Carbon black aggregate 330 180 Carbon black aggregate N990 0.15 5,000 0.8 Plasticizer ZnO Sulphur/Accelerator 0.008 0.008 Fig. 28 Comparison of the size of the components of a rubber compound 127 X E D N I

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Materials and Process Engineering In addition to the common technology of mixing in batches in kneaders (→ Fig. 29) and on mixing rollers, rubber compounds can also be produced continuously using extruder processes. These are less com- mon and, due to the longer start-up and shut-down times, are mainly used in mixing plants where large-volume com- pounds are produced with only a few formulation changes. The schematic structure of an internal mixer, also known as a ram mixer, is shown in → Fig. 29: The heart of the mixer is the temperature-controlled mixing chamber, which is closed by the ram and the fold- ing saddle in which two rotating mixing blades (rotors) provide the mixing power. Fig. 29 Structure of an internal mixer (here with a tangential rotor geometry) 128 They are either tangential (run next to each other with friction) or intermeshing (run in parallel with overlap). The mixing chamber, the rotors and the discharge saddle are temperature-con- trolled so that the heat introduced into the mix by the shear forces can be dissi- pated in a controlled manner. The advan- tage of the intermeshing rotor system is the higher energy input into the mix and therefore a significantly better dispersive mixing effect compared to tangential systems. Tangential internal mixers mix more gently and offer more mixing vol- ume for the same size. The pre-weighed raw materials are fed into the mixing chamber through the feed chute, which is closed with the plunger during the mixing process and thus keeps the mix under pressure. At the end of the mixing process, the saddle at the bottom of the mixing chamber is opened and the mix falls downwards out of the mixer. The mixing chamber volumes of conven- tional inline mixers range from 30 l to large mixers with over 700 l. Depending on the density of the raw materials, batch weights of 25 kg to over 500 kg can be achieved with these mixers. Due to the mixing and shearing energy required, high drive power is needed. Rolling mills are generally used as down- stream aggregates after internal mixers. The rollers of a rolling mill are operated at different speeds. The rear roller runs 10 to 30% faster than the front roller (friction), which creates the shear forces required for a good mixing effect in the roller gap.

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7. From raw material to finished part The gap width of the roller mills is adjusta- ble; the addition of mixing components takes place with a large gap width and the gap is reduced for subsequent homogeni- zation (→ Fig. 30). On the first roller mill, the mix, which can reach temperatures of more than +140 °C during the mixing process in the internal mixer, especially with high filler contents, is cooled to temperatures below +80 °C and homogenized again in the narrow roller gap. Temperature-sensitive raw materials such as cross-linking chemicals can be mixed in safely on the first roller mill. The second rolling mill is essentially used for remixing, shaping and transfer to the downstream batch-off system. Alternatively, mixtures can also be pro- duced in several stages. In the first step, the basic mixture is produced without temperature-sensitive chemicals and runs through the same mixer line again completely after depositing, whereby heat-sensitive raw materials such as cross-linking chemicals can be mixed in the internal mixer in the second pass. A higher mixing quality is often required for safety components or delicate sealing shapes such as sealing lips. Therefore, downstream homogenization via a mix- ing roller or a multi-stage mixing process is mandatory for these applications. Rub- ber compounds of these product groups are often subjected to an additional pro- cess step, straining. Using an extruder with fine-mesh nets, the compounds are strained under high pressure so that all particles as of a certain size, such as un- sheared mixture components or undivided oversized grains, are reliably removed. At the end of the mixing line, either mixing skins are cut, a wide endless belt is deposited or narrow strips are cut and also deposited endlessly in containers. For further processing, it may be neces- sary to change the shape of the rubber mixture, to continuously fill the molding machine or to be able to insert precisely fitting blanks into molding tools, for ex- ample. The mixture is therefore often formed into sheets, cords, strips or indi- vidual blanks using an extruder. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P Fig. 30 Illustration of a mixing roller 129 X E D N I

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Materials and Process Engineering This step is used exclusively for pre- forming and not for mixing in other raw materials. tolerances, the rubber compound is approved for further processing in the forming area. All steps in the production and preparation of the mix are subject to continuous quali- ty monitoring. In a certified mixing plant, all raw materials are sourced from certified suppliers. In addition to the manufacturer certificates of the individual raw material batches, the quality of the raw materials is randomly tested as part of the incoming goods inspection. After a positive result, the raw materials are approved for use. The mixing processes are precisely de- fined by operating formulation specifica- tions and exact mixing instructions with regard to weighing tolerances and the time at which the raw materials are added to the kneader or rolling mill. During the individual mixing phases, process param- eters such as energy input into the rubber mixture, rotor speed, temperature, mixing times, as well as stamp movement and pressure etc. are precisely controlled. Pro- cess specifications are also defined for the rolling mills, so that all process steps can be controlled until the finished com- pound webs are discharged into the batch-off system. If only a few batches of a rubber com- pound are produced, each batch is final- ly checked; for this purpose, the rheolog- ical properties as well as the density and the mechanical values (hardness, tensile strength, breaking strain, compression set, possibly others) are determined. For larger campaigns, the testing effort can be reduced in accordance with QS speci- fications by means of skip-lot random sample testing procedures. If all the measured values are within the specified 7.3 SHAPING AND VULCANIZATION Elastomer molded parts are usually man- ufactured using processes in which the shaping and vulcanization of the rubber compound take place in the same place and at the same time. In the manufacture of continuous rubber products such as hoses and profiles, however, the shaping is separated from the vulcanization in tems of space and time. CHOICE OF SHAPING PROCEDURE Various processes are available today for the production of elastomer molded parts. The choice of the most technologically and economically suitable process depends on the following parameters: y Number of units y Dimensions of the component y Flowability of the rubber compound y Component geometry and tolerances Tool costs play an important role in a profitability analysis and must be in a rea- sonable proportion to the requested number of units. The design of the molded part is also im- portant when considering costs, especial- ly the required tolerances and the finished processing state. Burr-free molded parts are often required on the inquiry drawings, which necessitates the complete deburr- ing in an additional process step. This is often not technically required for the ap- plication and can cause costs in individual 130

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7. From raw material to finished part cases that are higher than the total manufacturing and material costs of the molded part itself. It makes sense to specify the permissible burr expansion on the drawing, e.g. 0.3 × 0.5 mm (maximum dimension of the thickness and length of the burr). In the production of molded parts, dimension- al deviations occur due to manufacturing tolerances during tool production, the process for producing the elastomer com- pound, the molding process and the shrinkage behavior of the elastomer com- pound during vulcanization. The permissible tolerances for molded rubber parts are described in DIN ISO 3302. The following → Table 5 is an excerpt from part 2 of this standard. The stand- ard distinguishes between dimensions linked to the mold (F) and dimensions linked to the positive fit (C). Due to the process, the dimensions linked to the form fit (C) have a greater tolerance than the dimensions linked to the mold (F). CLASS M1 CLASS M2 CLASS M3 CLASS M4 F ± C ± F ± C ± F ± PERMISSIBLE DIMENSIONAL TOLERANCES IN mm 6.3 10 16 25 40 63 100 160 0.10 0.10 0.15 0.20 0.20 0.25 0.35 0.40 0.10 0.15 0.20 0.20 0.25 0.35 0.40 0.50 0.15 0.20 0.20 0.25 0.35 0.40 0.50 0.70 0.20 0.20 0.25 0.35 0.40 0.50 0.70 0.80 0.25 0.30 0.40 0.50 0.60 0.80 1.00 1.30 PERMISSIBLE DIMENSIONAL TOLERANCES IN % C ± 0.40 0.50 0.60 0.80 1.00 1.30 1.60 2.00 F ± 0.50 0.70 0.80 1.00 1.30 1.60 2.00 2.50 C ± 0.50 0.70 0.80 1.00 1.30 1.60 2.00 2.50 I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P NOMINAL DIMENSION FROM TO 0 6.3 10 16 25 40 63 100 160 0.30 (* 0.50 (* 0.80 (* 1.50 1.50 Tab. 6 Permissible dimensional tolerances for molded parts (DIN ISO 3302) (* – Values by agreement only) 131 X E D N I

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Materials and Process Engineering If no tolerance class is specified in the product drawing, class M3 (medium de- gree of accuracy) usually applies. Produc- tion in tolerance classes with a higher de- gree of accuracy only makes sense if this is crucial to the function of the compo- nent. Excessively tight tolerances make the product unnecessarily expensive. INFLUENCE OF THE RUBBER COMPOUND Not every rubber compound can be pro- cessed using every process. Formulations often have to be adapted when switching from one molding process to another. In order to assess the processing behavior of a rubber compound, its flowability and the speed of vulcanization (cross-linking kinetics) must be determined as a function of temperature. These rheological tests are carried out using appropriate rheome- ters, which are also used to perform a constant control of the materials – see also → „5. Cross-linking chemistry“, Fig. 21, page 116. The rheometer curve shows the change in torque over time at a fixed tempera- ture. As the cold rubber compound in- serted into the mold heats up, it initially begins to flow and the torque decreases. As soon as the cross-linking reaction be- gins, the flowability decreases and the viscosity of the mixture and thus also the torque increase. After vulcanization is complete, the torque no longer changes and reaches a stable final value (→ Fig. 21, page 116). It is the task of the compound developer to adapt the flow and cross-linking be- havior of the rubber compound to the re- spective processing method by adjusting the compound viscosity, selecting the cross-linking system and the remaining compound structure. TOOL COMPETENCE In addition to the compound composi- tion, the tool must also be matched to the selected shaping process. The right choice of tool steels and the manufacture and maintenance of the tools are important prerequisites for successful toolmaking and optimal elastomer processing. In general, tools are manufactured by machining such as turning, milling and drilling. How- ever, electro-erosion is also used as a machining process for many tools today. The correct choice of steel grade and the correct surface treatment of the molding tools are of particular importance, as rub- ber compounds sometimes contain a high proportion of wear-promoting fillers and cause corrosion on the tool steels due to ox- idizing precipitates during vulcanization. Stainless steels with more than 15% chro- mium as the main alloy component are of- ten used, which have a sufficiently high chemical resistance. Alternatively, the ground and polished tool surfaces can be made sufficiently wear-resistant and corro- sion-resistant by subsequent hard chrome plating or special coating. The quality of the tools and especially their surfaces must be monitored constantly and maintained through preventive main- tenance and repairs. The easiest way to do this is to assess the surface quality of the molded part itself. Even the slightest changes to the tool surface are visible as a mirror image on the molded part, often long before the dimensional change can be measured. 132

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7. From raw material to finished part However, the professional molding pro- cess is also suited for the production of very large component dimensions, for wind turbine seals, for example. The disadvantage is the longer heating times compared to the other methods, as the blank has to be heated from ambient temperature to mold temperature (usu- ally +160 – +180 °C). Depending on the size of the blank, this can take several minutes because rubber compounds generally conduct heat poorly. TRANSFER MOLDING The transfer molding process (TM) is a further development of compression molding. Here too, a blank is used, which in contrast to CM, is placed in a transfer unit that is connected to the actual mold via small channels. When the piston of the transfer unit is moved in, the blank is pressed and the rubber mixture is inject- ed via the channels into the hot, closed mold cavity, where it begins to vulcanize. The finished component and the remain- ing material in the transfer pot can be demolded as soon as vulcanization is complete. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P Fig. 31 Principle of compression molding – CM 133 X E D N I 7.4 OVERVIEW OF THE SHAPING PROCESS In discontinuous processes, the shaping of rubber compounds generally takes place at the same time as the chemical cross-linking reaction (vulcanization). In most cases, molding and vulcanization take place in closed molds (cavities). The most important molding processes for technical rubber products are: y Compression molding (CM) y Transfer Molding (TM) y Injection molding (IM; hot runner and cold runner technology) y Extrusion processes; roller head systems COMPRESSION MOLDING Compression molding (CM) is one of the oldest molding processes in elastomer processing. A prefabricated blank of a de- fined weight is placed in the open mold, which is preheated to vulcanization tem- perature, and formed by closing the mold in a press. The heated mold plates heat the blank, which begins to flow and fills the mold, allowing air and excess mate- rial to escape from the parting line of the mold. Once the flow process is complete, the rubber compound begins to vulcanize. The finished component can be demolded as soon as vulcanization is complete. The burr created along the parting line of the two mold halves must be removed in a subsequent process step. The advantages of compression molding lie in low-cost tools, which means that smaller quantities can also be produced economically. Efficiency can be increased by using multiple cavities, possibly with automated blank loading.

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Materials and Process Engineering The advantage of transfer molding is that several cavities can be filled simultane- ously with one blank and that the rubber mixture is better distributed through the channels, making more complicated designs possible. In addition, the blank is already heated in the transfer pot, which results in shorter closing times and reduces the formation of burrs on the component. INJECTION MOLDING In the injection molding (IM) process, the rubber compound is fed into a plasticiz- ing unit in the form of continuous strips or round cords, where it is preheated and then injected under high pressure via hot distribution channels into the hot, closed mold cavity, where the rubber compound begins to vulcanize once the mold is com- pletely filled. Transfer molding can therefore be used to produce medium to high-precision components economically. Vulcanized material in the channels and in the transfer unit as well as burr forma- tion on the component result in waste that must be disposed of. Components usually have to be reworked. The demands on the rubber compound are higher compared to CM: In order to be pressed through the channels, the rub- ber compound must flow better, and the early addition of heat and the longer flow paths must not lead to premature vulcan- ization. Fig. 32 Principle of transfer molding – TM 134 With this so-called hot runner technolo- gy, once vulcanization is complete, the vulcanized residual material is removed from the divider channels (sprues), sepa- rated from the component and disposed of in addition to the finished component. The position and number of injection points can be precisely matched to the component geometry and the compo- nent volume; working with multiple cav- ities, which can be individually injected, is also common. As the rubber compound is already pre- heated by the heatable screw conveyor and the mechanical work caused by plas- ticizing, it can flow much more easily through the narrow distribution chan- nels. The required vulcanization temper- ature is thus reached more quickly and very short closing times can be achieved, making the injection molding process the fastest of the three molding processes. Injection molding processes do not re- quire blank production and can be fully automated. Similar to transfer molding, the rubber mixtures must have good flowability; the advantages of short cy- cle times can be achieved above all with compounds that vulcanize quickly, which sometimes limits their storage stability.

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7. From raw material to finished part Fig. 33 Principle of injection molding – IM With increasing quantities, TM and IM processes become more interesting; CM is often the most economical for large outer diameters, even with larger quan- tities (→ Fig. 35). I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P Fig. 34 Principle of cold runner technology 135 X E D N I With hot runner technology, the sprues produced must be removed and disposed of after each cycle. This type of shaping is associated with high investment costs for injection mold- ing machines, tools and distribution channels, which is why injection molding processes are particularly economical for large quantities. COLD RUNNER TECHNOLOGY In the injection molding process with cold runner technology, the manifold plate in which the channels are located is thermally separated from the hot mold and can be individually temperature-controlled. This means that the rubber mixture re- maining in the channels does not vulcanize and there are no sprues that have to be separated from the component and dis- posed of. In addition to this additional process step, considerable material can also be saved, which can lead to a significant reduction in costs, especially with expensive rubber compounds. The injection molding process with cold runner technology is particularly well suited for the fully automated production of molded parts, as the use of so-called flashless tools means that rework-free components can be produced without waste. Here, too, the high investment and tool costs mean that the process only pays off for larger quantities. CHOICE OF PROCEDURE The cost-effectiveness of the three shap- ing processes depends primarily on the size of the component to be produced and the required quantities.

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Materials and Process Engineering EXTRUSION PROCESS Extrusion processes allow for the contin- uous production of endless components such as hoses, cables, profiles or sheet ma- terial. The rubber compound is drawn into the extruder and continuously conveyed by the rotating screw, heated and pushed out through a die nozzle at the end of the extruder. The profile cross-section is shaped in the process. In addition to prod- ucts such as round cords, cables or hoses with simple cross-sections, complicated geometries, such as those used in sealing or hollow chamber profiles, can also be re- alized (→ Fig. 37). A frequently occurring phenomenon in the extrusion of polymers, in which a polymer strand is pressed through a die to produce the desired sample, is strand expansion. Depending on the rubber compound and the process parameters, it ensures a significant increase in the di- ameter of the rubber strand after it has passed through the narrow openings of the die (→ Fig. 37). Fig. 36 Examples of strand expansion The reason for this is the viscoelastic ma- terial behavior of the rubber compound, whose polymer molecules disperse sig- nificantly as they pass through the tool nozzle and then return to their lower- energy ball state. When running in a new nozzle disc, an iterative adjustment process is usually required until the desired target contour is achieved. The extruder is followed by equipment used to vulcanize the extrudate. The cross-linking of the rubber mixture is either continuous or discontinuous. y t i t n a u Q TM Transfer Molding IM Injection Molding CM Compression Molding Fig. 35 Influence of component size and quantity on the economic efficiency of shaping processes Outer diameter [mm] 136

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7. From raw material to finished part y sufficient surface quality: both after extrusion and after the vulcanization process Both the expansion of the strand and changes in shape until the elastomer is fully cross-linked are subject to certain fluctuations and are the reason why the usual tolerances cannot be realized in the extrusion production of elastomer articles. Manufacturing tolerances for extrudates are specified in DIN EN ISO 3302-1 E1 to E3. The usual standard E2 is approx. 3 times higher than the usual standard M3 for mold-bound processes, which must be taken into account when designing the product (→ Table 6). Deviations from the standard can occur and must be checked depending on the material, vulcanization process and contour complexity. Profiles used in sealing technology can be supplied by the meter or in prefabricated form (e.g. sealing rings, profile sections). Water Steam Filling opening I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P Fig. 37 Extruder for the production of sealing profiles 137 X E D N I With continuous production, the heat re- quired for vulcanization is introduced into the molded rubber compound using infra- red radiators (IR), hot air systems (HL) or microwave systems (UHF), often in com- bination. Alternatively, the extrudate can also be passed through a hot salt bath. In all processes, the material is brought to temperature without pressure and cross- linked. The rubber mixture must be adapt- ed to the pressureless vulcanization and must not contain any components that can outgas or form gaseous components in the heat, as the extrudate would other- wise foam up and form an irregular sur- face. In discontinuous production, cross-linking takes place in an autoclave with steam. The pressure acting on the material pre- vents the outgassing of volatile compo- nents and thus the formation of pores in the component. The composition of the rubber compound is less critical here. The choice of the appropriate production process is primarily dependent on the ma- terial as well as the geometry and thick- ness of the cross-section. For example, an inherent curvature required for the appli- cation can be vulcanized into the profile in the autoclave, which is not possible in con- tinuous production. Regardless of the manufacturing process, an extrudable rubber compound must meet the following criteria: y reproducible strand expansion y stability: The still uncured mixture must not deform or “flow away” in an undefined manner after molding, but must have sufficient dimensional sta- bility for the subsequent process steps

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Materials and Process Engineering During assembly, a seal is produced from the finished vulcanized yard goods in fur- ther work steps. The most common prod- uct is a closed sealing ring in which a joint is created by gluing or impact vulcaniza- tion. From a technical point of view, this joint always represents an area of lower quality (surface quality, tensile strength, elongation at break), which must be tak- en into account in the subsequent appli- cation. When bonding, the sealing profile is usu- ally cut at an angle; this increases the bonding surface and leads to a higher load-bearing capacity of the joint. The choice of adhesive must be matched to the elastomer. Above all, the temperature and media resistance, but also the stiff- ness and elasticity of the adhesive should be comparable to those of the elastomer. During butt vulcanization, the sealing profile is usually cut at right angles. The ends to be joined are joined under pres- sure and temperature in a vulcanization tool that reproduces the negative shape of the sealing profile. Before the mold closes and the two ends are joined to- gether, a thin film of the elastomer raw compound is placed between the ends, which enables the two profile ends to form a tight fit. The joint created in this way has the same flexibility and identical media and temperature resistance as the base material of the sealing profile. From a technical point of view, butt vulcanization is therefore the preferred solution. ROLLER-HEAD SYSTEM Flat material is also produced from sheets and webs. This is primarily used in sealing technology as a semi-finished product for further processing into flat gaskets and NOMINAL DIMENSION [mm] TOLERANCE CLASS [mm] FROM TO E1* E2 E3 0 1.5 2.5 4.0 6.3 10 16 25 40 63 1.5 ±0.15 ±0.25 ±0.40 2.5 ±0.20 ±0.35 ±0.50 4.0 6.3 ±0.25 ±0.40 ±0.70 ±0.35 ±0.50 ±0.80 10.0 ±0.40 ±0.70 ±1.00 16 25 40 63 ±0.50 ±0.80 ±1.30 ±0.70 ±1.00 ±1.60 ±0.80 ±1.30 ±2.00 ±1.00 ±1.60 ±2.50 100 ±1.30 ±2.00 ±3.20 Tab. 7 Manufacturing tolerances according to DIN EN ISO 3302-1 (* partially possible in individual cases) membranes. The flat material is produced using pressing tools as individual sheets or continuously as sheet material in so- called roller head systems. An extruder – equipped with a wide ex- trusion head and wide slot die – feeds the plasticized and heated rubber mixture into a 2-roll calender. In the roll nip, the web is calendered to a defined thickness and width and then pressed against a rotating heating roll with the help of a steel belt and continuously vulcanized. Map-Marker-Exclamation Connection points must be taken into account in the application 138

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7. From raw material to finished part I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A Extruder Two roll calender Filing R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H Fig. 38 Principle of a roller head system The edges are then trimmed, the surface powdered if necessary and the sheets rolled up or cut into strips or individual sheets. When producing sheet material, a second component (e.g. PTFE film as a permea- tion barrier, fabric for mechanical rein- forcement) can also be fed into the system and be chemically bonded with the elas- tomer during vulcanization. The flat material is assembled into flat gaskets by means of separating post- processing (e.g. punching, drilling, plotting, cutting, laser or water jet cutting). (PRESS) SINTERING OF PTFE Sintering is generally a process in which powdery or granular starting materials are mixed and "baked" together by pressing, usually under temperature and pressure. There are processes in which agglomer- ates are first pressed into a mold and baked under high pressure and tempera- ture. There are also processes in which work can be carried out without pressure. ticles, the process differs from casting processes in that in the latter the entire component is formed from a melt. Sintering processes are widely used in ceramics production and metallurgy, but are also used in the manufacture of semi-finished products made from non- fusible plastics such as the ultra-high- molecular-weight plastics polyethylene (UHMPE) and polytetrafluoroethylene (PTFE). Pressing and sintering technologies enable the production of geometrically simple semi-finished products such as solid rods, hollow rods and sheets. Due to its high molecular weight and the associated high melt viscosity, PTFE can- not be processed using typical thermo- plastic processing methods such as injec- tion molding or blow molding, although it is a representative of the thermoplas- tic material class. In the melting range of approx. +340 °C, PTFE still has a solid, gel- like consistency. For this reason, the press- sintering process is used for shap- ing (→ Fig. 39). Even though sintering processes are ulti- mately based on the melting of solid par- The production of molded parts made of PTFE takes place in several steps: R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 139 X E D N I

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Materials and Process Engineering 1. the PTFE compound is premixed and filled into the mold 2. the PTFE compound is pressed into a green compact at specific pressures > 250 bar 3. the greenling is sintered into a semi-finished product at tempera- tures > +360 °C 4. the semi-finished product is processed mechanically after completely cooling To improve certain properties, fillers are added to the PTFE powders before sinter- ing to increase the hardness of the mate- rial, improve its wear resistance and re- duce the tendency to cold flow. Organic fillers such as glass, carbon, graphite, bronze, molybdenum sulphide and ceramic powder are commonly used. Powdery, high-melting thermoplastics such as polyether ether ketone (PEEK) are also used. The PTFE compound is mechanically sealed at pressures of between 250 and 700 bar. Further processing of these blanks, known as "green compacts," then takes place in special sintering ovens. Here, the green compact is sintered into a homogeneous structure in defined sintering cycles, which are selected de- pending on the PTFE type, the fillers and the wall thicknesses. The usual sintering temperature is between +360 °C and +380 °C. As the individual PTFE particles do not melt, pores remain in the finished product. The pore size can be adjusted very precisely by selecting the starting material used, its particle size and the process parameters. After sintering, the pressed part must be cooled slowly under defined conditions. When the crystallization temperature is reached, the pressed parts shrink consid- erably and can sometimes build up high stresses, which can lead to cracks if they cool down too quickly. After the semi-finished products have cooled down completely, they are ma- chined into foils and punch outs by using machining processes such as turning, drilling or milling or by peeling them into form. The most common processing technolo- gies are listed below: Open tool Fill tool Close tool and press Mold opened – green compacts demolded Fig. 39 Production of hollow cylinders by way of press-sintering 140

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7. From raw material to finished part Press position p Filling position p Cooling PTFE granules Heated extrusion tool (approx. +380 °C) Fig. 40 Principle of ram extrusion y manual press-sintering process for the production of semi-finished products (→ Fig. 39) y ram extrusion for the production of endless rods and tubes (→ Fig. 40) y tableting process – fully automated press-sintering process for the produc- tion of complex molded parts with or without mechanical post-processing y automatic press-sintering process for the production of thin-walled hollow cylinders In ram extrusion, the free-flowing PTFE compound is sealed into the shaping ex- trusion cylinder in batches using a ram. The ram is lifted after a certain time and new powder is metered into the cylinder. Various heating zones along the ram extrusion die ensure that the individual dosing batches are sintered together to form a continuous extrudate. Ram extru- sion is used to produce rod-shaped semi-finished products (solid rods, hollow rods, hoses) quasi-continuously. 7.5 PLASTIC PROCESSING Thermoplastics and thermoplastic elasto- mers such as thermoplastic polyurethane can also be molded into components using a variety of different processes. Classic plastic injection molding is certainly the most widespread alongside extrusion. In contrast to the injection molding of rubber compounds, the injection mold- ing of thermoplastic materials does not include an additional vulcanization step. The main differences between the two I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 141 X E D N I

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Materials and Process Engineering Elastomer → long cycle time → vulcanization Thermoplastic → short cycle time → physical solidification or crystallization +160 °C … +190 °C +60 °C … +80 °C String or strip +30 °C … +70 °C +170 °C … +350 °C Granules recyclable Fig. 41 Comparison of rubber and thermoplastic injection molding IM processes lie in the way the materials are fed, the temperature control and the requirements placed on the molds (→ Fig. 41). In contrast to rubber injection molding, thermoplastic injection molding involves injecting the polymer melt, which has been heated above the glass or melting point, into the cold mold, from which the component can be demolded after com- plete solidification or crystallization. Thermoplastic and TPE melts are generally much thinner than heated rubber mixtures – which is why tools for thermoplastic in- jection molding must be manufactured with significantly higher precision. For further details, please refer to the relevant literature. 142

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8. TESTING METHODS 8. Testing methods Material testing Elastomers must be able to withstand a wide range of stresses in their applications. A wide variety of properties such as strength, setting behavior, abrasion, per- meation or resistance to media are re- quired, which can only map the complex situations of real applications in combina- tion. The user must therefore be able to evaluate these properties neutrally, reproducibly and unambiguously. For this reason, test methods and test procedures are developed, standardized and applied in qualified laboratories such as those of the Freudenberg Group (see also → chapter “Services”, page 7). Freuden- berg laboratories are regularly certified or accredited in order to meet their own high standards. The following chapter is intended to in- troduce the reader to the most common test methods and provide an overview of the test procedures. The use of the test methods goes beyond the mere description of the requirements for the application of the sealing prod- ucts. It begins with raw material control and material development and extends to the processing phase of the compounds, vulcanization and damage analysis in the event of a complaint (→ Fig. 42). The various test methods can be divided into groups that describe their purpose and background. The illustration → Fig. 43 shows a selection of the methods used and classifies them according to the over- riding effects. TESTING OF ELASTOMERS Development: Recipe development Test specimen production Approval Material testing Production: Mixing process Processing process Approval Testing: Vulcanized raw mix Material testing Testing of the finished part Failure analysis: Material testing Testing of the finished part Fig. 42 Testing elastomers I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 143 X E D N I

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Materials and Process Engineering PROCESSING PARAMETERS Cross-linking kinetics Flow behavior Batch variance STATIC-MECHANICAL PROPERTIES Density Hardness Stress/strain (tensile test) DVR tear propagation property Volume change DYNAMIC-MECHANICAL PROPERTIES Frequency behavior Temperature-frequency superposition Fatigue test Tg determination RESISTANCES CALORIC PROPERTIES ELECTRICAL PROPERTIES Storage • Media • Ozone • Light Relaxation Chemiluminescence Thermal capacity (DSC) Thermal conductivity Thermal expansion Surface and contact resistances Dielectric strengths DIFFUSION PROPERTIES TRIBOLOGICAL Gas and liquid permeation Leakage measurements Pore distribution Coefficient of static and dynamic friction Wear measurements Speed-, pressure- and media-dependent tribology studies Fig. 43 Types of tests for rubber PROCESSING CHARACTERISTICS Density Density is one of the most basic param- eters and is determined according to the DIN EN ISO 1183 standard. density of elastomer materials is largely independent of the selected measure- ment method and can be regarded as spe- cific. This is referred to as a "fingerprint method." Material mix-ups can usually be clarified using a density measurement. The individual composition of each raw compound from different base materials makes it easy to differentiate between materials on the basis of density. The Density: p = m  V 144

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8. Testing methods Torque detection with every oscillation Oscillation with variable frequency and amplitude Fig. 44 Schematic structure of a volcametric measuring cell As the degree of cross-linking increases, the torque increases until the cross-link- ing process is complete. The course of the vulcanization can be read off directly. By varying the temperature, the mixture- dependent crosslinking kinetics can be determined and transferred to the pro- duction process. +190 °C +180 °C +170 °C Cross-linking kinetics The speed at which the raw mixture be- comes an elastomer in the hot mold through crosslinking is important from a technical and economic point of view. On the one hand, the raw mixture is no longer capable of flowing after cross- linking begins, so it must therefore have plastically mapped the cavity of the manufacturing tool. On the other hand, the elastomer product should not remain in the subsequent mold longer than necessary in order to avoid reversion effects, for example, and to make it possible to work economically. The vulcanization parameter test is the best way to describe the cross-linking process. A fixed volume of the raw mix- ture is placed between two oscillating, structured chamber halves that are heat- ed to the crosslinking temperature. The measured variable is the time-dependent torque required to carry out the oscillation movement. ] m N [ e u q r o T 0 1 2 3 4 5 6 7 8 9 Time [min] Fig. 45 Rheometer curve I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 145 X E D N I

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Materials and Process Engineering 1ste Newtonian region Shear thinning area Stick-slip Area with possible wall sliding ] s a P [ y t i s o c s V i 1,000,000 100,000 10,000 1,000 100 10 1 1E-03 1E-02 1E-01 1E+00 1E+01 1E+02 1E+03 1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 Shear rate [1/s] Fig. 46 Shear rates Flow behavior Modern injection molding processes re- quire precise knowledge of the behavior of the raw mixture during the injection process. Shear thinning, wall slip, strand swelling and melt fracture are just some of the phenomena that should be de- scribed depending on the material. An ex- ample of this is viscosity, which decreas- es significantly in rubbers over the shear rate (speed at the same channel cross-section). High-pressure capillary rheometry provides reliable measured values for this, which are required to de- sign the vulcanization tools or their flow channels (→ Fig. 46). However, measure- ment technology alone would not be able to adequately describe flow behavior. Only in combination with simulation methods can the measured values gen- erated help to achieve the tool design with minimal reworking. This interplay between a suitable test method, deter- mined characteristic values and suitable simulation tools will be discussed again elsewhere in this chapter. Practical combination of vulcanization and flow behavior In production-related applications, it has proven useful to use a method that forms an intersection of the two methods de- scribed above. With the “Rheovulcame- ter" measuring method, it is not possible to determine exact characteristic values for viscosities or reaction times during 146

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8. Testing methods The individual hardness tests differ accord- ing to the geometric shape of the indent- ers (cone, truncated cone or ball), size and type of load as well as other parameters during the test (measurement duration, contact surface, thickness of the test specimen, distance to the edge of the test specimen, etc.). The local deformation of the material is made up of different parts of compressive, tensile and shear deforma- tions. The determination of the hardness is therefore dependent on the visco elastic properties of the materials. → Fig. 48 shows an overview of the most commonly used methods. There is no linear correlation between the individual methods and it is not possible to convert Shore A to IRHD, for example. Experience shows that for soft, highly elastic compounds, the Shore A and IRHD standard measurement values are almost identical, whereas for materials with higher hardnesses, the IRHD measure- ment results in higher measured values in comparison. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P Fig. 47 Rheovulcameter: Test device setup and use of the tool 147 X E D N I vulcanization, however comparative tests between different compounds or, in the case of a compound development, the influence of individual components on the flow behavior can be carried out very quickly and meaningfully. An exact amount of raw mix is pressed through a capillary into a defined test tool. If the test parameters are kept constant, the filling level of the tool is an indicator of the quality of the manufacturing process as a whole. Parameters for simulations cannot be determined here. STATIC-MECHANICAL PROPERTIES Hardness test One of the most basic mechanical tests is the so-called hardness test. It is a simple, quick and therefore inexpensive method. In principle, the term "hardness" refers to the resistance of a body (mate- rial) to the penetration of a harder body (indenter) under a defined force. In the case of metals, this creates a plastic im- pression that must be measured after the force has been removed in order to deter- mine the hardness value. As elastomers recover elastically after being deformed by the indenter, the indentation depth is measured here during the application of force. (With plastics, both methods are used depending on the type.) With elastomers, the test basically follows two different procedures. One is the applica- tion of a constant weight force (IRHD) or deformation by a defined spring force (Shore). The hardness numbers represent units derived from the penetration depth and cover a range from 0 to 100 degrees of hardness. The measured values are dependent on the viscoelastic properties, in particular the stiffness or the stress value.

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Materials and Process Engineering Shore A (DIN 53505) IRHD sub-range soft (DIN 53519) 10 10 90 40 35 98 IRHD sub-range normal (DIN 53519) Shore D (DIN 53505) Ball pressure hardness (DIN 53456) 30 90 1.0 48 Fig. 48 Overview of common hardness testing methods for rubber and TPE softer harder hardness y uneven test specimens; the specimen and the measuring device must always be kept parallel Standards: y ISO 48: IRHD (method M describes the microhardness test with a significantly smaller indenter (half sphere 0.4 mm) y ISO 868: Replacement for DIN 53505: Shore hardness Hardness measurements and specifica- tions are generally subject to a fluctuation range of ±3 hardness points due to the system. This information does not take material variations into account. In principle, the hardness tests are carried out on test specimens prepared from so- called test plates (the geometry is deter- mined by the standard). Small residual samples or finished parts can be deter- mined using the microhardness test. The measuring accuracy decreases, however. Areas of application for hardness testing include batch control, undercrosslinking, material mix-up, hardening or softening of the material due to ageing and mate- rial homogeneity. Possible errors are: y sample thickness is too low → leads to higher measured values (standardized thickness: 6 mm). The same applies to excessive contact pressure y measurements are too close to the edge, e.g. if the molded parts are too small → the values are too low 148

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8. Testing methods I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A Tensile strength R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H Elongation at break R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P 200 mm/min S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P ] a P M [ i n o s n e T 30 25 20 15 10 5 0 Span value at 300 % 0 100 200 300 400 500 600 700 Elongation [%] Fig. 49 Stress-strain diagram i n o s n e T Steel i n o s n e T High deformation speed Low deformation speed Thermoplastic Elastomer Pseudo-static behavior Fig. 50 Stress-strain diagram. Left: Comparison of steel, thermoplastic, elastomer. Right: Behavior of elastomers at different deformation speeds. Stretching Stretching C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 149 X E D N I

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Materials and Process Engineering Tensile tests After the hardness test, the tensile test is the most widely used test method for elas- tomers. Defined test specimens in rod or ring form are clamped in appropriate clamping or holding devices and stretched at a constant speed until they break. The speed is low and constant; this is referred to as the quasi-static characteristic value (→ Fig. 49). The primary measurement variables are the force required for stretching and the path or distance covered. From this, the variables stress (from specimen geome- try and force) and relative strain (from specimen geometry and displacement) are determined and displayed in the stress-strain diagram. The course of the stress over the elonga- tion is non-linear in elastomers, which is why no modulus of elasticity can be deter- mined. Instead, the stress value deter- mined at a fixed strain (e.g. 50, 100, 200% etc.) is a reliable variable. For elastomers, this value is also referred to as the modulus, e.g. modulus 100 (stress value at 100% elongation). It re- flects the "stiffness" of the material at the corresponding elongation and correlates within limits with the hardness (→ Fig. 50). A C D B Fig. 51 Shoulder bar according to ISO 37 (edition 12-2011) 150 All values determined are characteristic values and not material constants. They are therefore dependent on the test conditions, e.g. specimen geometry and pull-off speed. Tensile tests are carried out as standard on virgin samples, i.e. the test specimen has not previously been subjected to any load. This eliminates the effect of stress softening (Mullins effect), which can occur when products are used later. Elastomers can be regarded as isotropic, which means that their properties are independent of direction if they are manufactured ideally. However, the manufacturing process of the test specimens or their removal from finished parts can lead to orientation of the polymer chains. These effects must be taken into account during testing. The tensile properties are dependent on tem- perature and humidity and must therefore be tested in a standardized climate. Areas of application are the determina- tion of static strength values, quality and batch controls as well as testing the im- pairment of elastomers due to influenc- es during use, e.g. operating media, light, heat and oxygen. When using the values determined for component design, the standardized tensile test can hardly be used, as effects such as changes in entro- py with temperature, stress softening, dynamic hardening and geometric influ- ences are not taken into account. Depending on the standard (e.g. DIN 53504 or ISO 37), the tests are carried out with test rods or rings that are machined from a test plate. The direction of removal must be kept the same. The production of the test plate blank can lead to an anisotropic influ- ence on the actually isotropic elastomer.

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8. Testing methods I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I SHOULDER BAR R O F S L A E S Y R A T O R S N O T A C I I L P P A 75 50 35 12.5 ± 1 8.5 ± 0.5 6 ± 0.5 25 ± 1 16 ± 1 12 ± 0.5 TYPE 1 TYPE 1A TYPE 2 TYPE 3 TYPE 4 DIMENSIONS [mm] Total length A Width of heads B Length of the bar C 115 25 ± 1 33 ± 2 100 25 ± 1 21 ± 1 Width of the bar D 6.2 ± 0.2 5 ± 0.1 4 ± 0.1 4 ± 0.1 2 ± 0.1 Thickness of the shoulder bar 2 ± 0.2 2 ± 0.2 2 ± 0.2 2 ± 0.2 1 ± 0.1 Initial gauge length 25 ± 0.5 20 ± 0.5 20 ± 0.5 10 ± 0.5 10 ± 0.5 Tab. 8 Dimensions of the shoulder bars according to ISO 37 (issue 12-2011) Standards here are, for example, DIN 53504 and ISO 37. Care must be taken to air- condition the samples (→ Fig. 51 and → Tab. 8). Elastomers react sensitively to changes in temperature and possibly also humidity. DIN 53504 specifies a feed speed of 200 m/min for S2, S3 and S3A. Larger bars (S1 and S1A) are tested at a higher speed of 500 mm/min. COMPRESSION SET When it comes to assessing the suitabil- ity of an elastomer as a sealing material, testing the compression set is extremely important. It describes the viscoelastic behavior of elastomers under constant pressure and constant deformation. ISO 815 is one of the most widely used test standards. A cylindrical specimen of a certain height (h0) is compressed by a percentage of its height (standard: 25%). Hard materials are compressed less. In this state, the test specimen is subjected to stress at an increased/decreased tem- perature. The duration and temperature level are regulated by the respective spec- ification or result from the question to be answered (e.g. application temperature). After temperature storage, the specimen is relaxed again, removed from storage and its new height measured. From the initial height, pressed height and height after removal from storage, the percent- age recovery can be determined. If the specimen has almost completely recov- ered, i.e. its height after storage almost corresponds to the initial value, its residual deformation and thus also the compression set is low. If the specimen remains deformed after storage, i.e. its height almost corresponds to the height in the compressed state, the compression set is high. The specified numerical value is a percentage expression of the residual deformation (→ Fig. 52). R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 151 X E D N I

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Materials and Process Engineering Delivery Deformation at constant temperature h0 F F hs Recovery after deformation Calculation of the compression set C h1 C = h0-h1 h0-hs · 100 % Fig. 52 Calculation of the compression set Depending on the instructions, the body is removed from the device before or after cooling and the height (hs) is meas- ured again. The compression set is then determined using the following formula. In addition to being able to make a state- ment on sealing behavior/ageing under operating conditions by using long test times, the compression set can also allow for a statement to be made on the state of vulcanization with short test times. The suitability of the material for static sealing can be determined by measuring the temperature near the glass transition or crystallization points. TEMPERATURE-FREQUENCY BEHAVIOR Elastomers are entropy-elastic materials. The key to this property is the ability of the macromolecules, often called chains in the case of rubber, to move. Their elasticity is based on the tendency of these polymer chains to repeatedly bring themselves back into a "knotted" state (similar to a ball of wool) and increases with increasing temperature. If energy is removed from this system, e.g. by lowering the temperature, the movement of the polymer chains is re- stricted or completely frozen (→ Fig. 53). In this state, the elastic, stretchable material has become a rigid, brittle body that with- stands compressive or tensile stresses with a stiffness higher by several factors, or breaks. The temperature at which the struc- ture transitions from rubbery to glass-hard is called the glass transition temperature. Compared to the very precisely defined melting temperature of water, the glass transition temperature is more of a tran- sitional range in the temperature spec- trum and is heavily dependent on the test method. In the past, many different test methods were standardized to describe the behav- ior of elastomers at low temperatures and to determine the glass transition tempera- ture. The characteristic values determined for the "freezing" of the elastomer differ considerably in some cases and are not systematic (→ Tab. 9). 152

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8. Testing methods The interpretation is therefore by no means simple and must be left to the experts. This is partly due to the fact that the be- havior of elastomers is not only depend- ent on temperature, but that their reac- tion also depends on the speed at which the stress is applied. As already shown in the tensile test, the resistance to a movement increases with the speed at which it is carried out. The explanation can again be found in the macro-molecular structure of the mate- rials. In the event of stretching, the elas- tomer matrix is forced into an external order. The chain structure is brought from the "ideal" ball into a stretched structure. In addition to the effort to re- turn to the lower-energy, free-moving state, energy must also be absorbed to organize the molecular strands when the chains are stretched. The faster the elas- tomer has to perform the movement, the greater the energy required. TEST PARAMETER Gehmann test T100, T10, T5, T2 Cold brittleness TS, TB Temperature retrac- tion test TR10, TR30, TR50, TR100 Torsional vibration test Differential thermal analysis TÜ, TR TR Tab. 9 Different methods for describing the glass transition temperature 10.000 ] a P M [ G 1.000 100 10 1 glass-elastic area rubber-elastic area TG –150 –100 –50 0 +50 +100 +150 +200 +250 Temperature [°C] Fig. 53 Modulus behavior of polymeric materials over temperature Duromer Thermoplast Elastomer I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 153 X E D N I

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Materials and Process Engineering Temperature behavior at constant frequency Frequency behavior at constant temperature glass elastic glass elastic l G s u u d o m r a e h S rubber elastic rubber elastic –150 –100 –50 0 +50 +100 +150 +200 +250 10-4 10-2 100 102 104 Temperature [°C] Frequency [Hz] Fig. 54 Mirror image diagrams of the temperature and frequency behavior of elastomers If the speed is so high that these ordering processes cannot be carried out properly, the chains hinder each other, the move- ment is even prevented. The elastomer then stiffens to the same extent as when it passes the glass transition point and can also break in the process. If the frequency is selected as a measure of the time dependency instead of the speed, the result is a mirror image of the temperature dependency (→ Fig. 54): high frequencies and low temperatures both lead to stiffening of the elastomer. Even in the state of limited mobility, the suitability as a sealing material depends on the respective application and must be determined experimentally. With dynamic mechanical analysis, a method can now be used in which the frequency, amplitude and temperature can be adapted to the load on a seal, mak- ing its behavior easier to predict. If the statement cannot be made directly, the results of a DMA test can at least be used as parameters in a component simulation. INFLUENCE OF MEDIA: STORAGE TESTS One of the main functions of a seal is to separate media. For example, a plug-in coupling sealed with an O-ring separates water from air in the garden, and the seal in the area of a cylinder liner separates coolant from engine oil. In each case, elas- tomeric sealing materials are influenced by the respective medium. For the mate- rial developer and for the user, the key factor is whether the effects are suffi- ciently small so as not to jeopardize the service life of the seal in the application. With regard to the effect of media, a general distinction can be made between physical and chemical influences. In the case of physical interaction or physical "swelling," the medium to be sealed in the elastomer becomes soluble due to 154

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8. Testing methods the chemical similarity (e.g. polarity). If the solubility is high, the additional liquid molecules now present in the elastomer cause the seal to increase in volume (swell). With poorly selected material combinations, the increase in volume can be several 100%, but is completed after a certain time (equilibrium reaction). Caused by the volume change/media ab- sorption, other properties of the sealing material such as hardness, elongation at break and strength as well as damping properties also change. In contrast to chemical interaction or chemical attack, this effect is largely reversible. If the me- dium can be driven out of the elastomer again, the elastomer behaves as it did be- fore the medium was absorbed. A related effect is the extraction of in- gredients from the elastomer into the surrounding liquid. Due to their better solubility in the liquid, constituents of the elastomer diffuse out of the matrix and into the liquid. If the elastomer consists of a significant percentage of these soluble substances, the result can be volume shrinkage, which can lead to leakages in seals due to a lack of compression. If key parts of the elastomer, such as poly- mer chains or crosslinking points, are af- fected by the medium, a chemical attack takes place. In this case, in addition to a superimposed physical absorption of the medium, the ongoing chemical change (e.g. chain degradation) can lead to an in- definite increase in the volume of the elastomer. In addition, embrittlement without further volume increase is also possible. In any case, the process is not reversible. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P ] C ° [ e r u t a r e p m e t g n i t a r e p o m u m x a M i +275 +250 +225 +200 +175 +150 +125 +100 +70 +50 PTFE FFKM FKM FVMQ ACM HBNR ECO TPE-E NBR VMQ PVMQ AEM CR AU SBR EPDM IIR NR 0 20 40 60 80 100 120 140 160 Swelling in reference oil IRM 903 [%] Fig. 55 Heat and oil resistance of elastomers (according to ASTM D 2000) C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 155 X E D N I

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Materials and Process Engineering Temperature and concentration influ- ence both the speed and strength of the observed effects of all three phenomena described. Not just liquids, but also gases can trigger the phenomena described. The selection of the correct sealing ma- terial cannot be made without having knowledge of its behavior under the in- fluence of media. Therefore, the exact de- termination of the phenomena described above plays an important role. In the simplest case, the necessary test specimens (e.g. tensile bars or circular blanks for volume determination, etc.) are placed in a glass vessel in such a way that they are surrounded by a predetermined excess volume of the respective medium. The vessel is stored in the heating cabinet at a defined temperature for various peri- ods of time and the change in the material properties relative to the properties be- fore the start is determined. Such a test must be carried out according to precisely defined parameters, as the normative Media attack Pressure Radiation Heat Oxygen Swelling Shrinkage Temperature Dynamic stress Ozone Wear and tear Friction Fig. 56 Ageing processes 156 basis (e.g. ISO 1817) alone is not sufficient to achieve good reproducibility. Without the appropriate expertise and experi- ence, results are not reliable. This applies equally to the determination of media stability in complex storage conditions such as in pressure vessels, in the vapor phase or with media that change over time and need to be replaced regularly. Low volume swelling of the seal does not pose a risk to the function if the installa- tion space is designed properly. Volume shrinkage, on the other hand, is to be looked at critically. There is no elastomer that meets all requirements for oil resist- ance, heat resistance and cold resistance in equal measure. The ambient medium and the temperature conditions in the application must therefore be taken into account when selecting the right sealing material. The chemical principle "like dis- solves like" applies. This means, for exam- ple, that polar elastomers (e.g. NBR) swell strongly in polar media (e.g. glycol), while non-polar elastomers (e.g. EPDM) are not resistant in non-polar media (e.g. mineral oil). Further information on the suitability of elastomer materials in selected sealing media can be found in the appendix to this chapter (→ “12. Chemical resistance”, page 180). HEAT RESISTANCE, AGING BEHAVIOR Elastomers, like all organic materials, change their properties during use. This is triggered by external influences (such as oxygen, temperature, media, radiation, dy- namic stress, etc.) that affect them during their service life. The generic term is ageing. The extent to which the effects affect the elastomer depends on the duration and strength of the effects. The higher the act- ing temperature, for example, the shorter

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8. Testing methods Exposure to oxygen and temperature O2 Chain dismantling Networking reduction Post-networking Fig. 57 Effects of ageing on the polymer structure the service life of a part. This results in dif- ferent maximum permissible operating temperatures for short and continuous loads for the individual materials (cf. → “4. Understanding Elastomer Formula- tions – Anti-Ageing Agents”, page 109). On the other hand, the limits depend on the suitability of the elastomer and, above all, the base polymer. The properties of the respective polymer class can certainly be improved by skillful compounding. To assess the ageing behavior, the changes in hardness, tensile strength and elonga- tion at break as well as the compression set are usually determined. This is done after storage in a heating cabinet (DIN 53508). Ageing is recorded at an increased temperature and with a shortened test time. Test temperature and actual oper- ating temperature should not differ too much, however (cf. → “14. Common terminology – RGT rule”, page 219). For the entropy-elastic material family of elastomers, it is mainly the changes in their cross-link structure that are decisive during ageing. A distinction is essentially made between three processes: chain scission, the degradation of cross-linking sites and the formation of new cross-link- ing sites, known as post-cross-linking. In the first two cases, ageing leads to sof- tening of the material, which can go as far as making the surface sticky. The lat- ter effect leads to brittleness or is associ- ated with an increase in hardness. From a scientific point of view, all effects occur side by side during ageing. Depending on the strength and speed of the reactions, macroscopic enlargement or hardening occurs (→ Fig. 58). CHEMO-STRESS RELAXATION With the help of the chemo-stress relax- ation test method, ageing processes can be described precisely and the effects mentioned can be investigated. Within certain limits, it is even possible to estimate the service life. This requires testing at several, usually high temperatures. In order to better assess the various chem- ical ageing influences, the measurements I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 157 X E D N I

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Materials and Process Engineering relative tensile stress [%] Material: NBR (peroxide cross-linked) -1 1000/T [K ] 180 160 140 120 100 80 60 40 20 = 0,25 % +100 °C +110 °C +120 °C +100 °C +100 °C cont. Air cont. Air cont. Air discont. Air cont. N2 E = 122 kJ/mol A 3,0 2,9 2,8 2,7 2,6 2,5 2,4 2,3 0 -2 10 -1 10 0 10 1 10 2 10 3 10 2,2 4 10 Time [h] Fig. 58 Service life prediction based on the extrapolation of the measured values of the voltage relaxation are also carried out in nitrogen or in liquid media for comparison. An Arrhenius plot of the results allows extrapolation to long exposure times at lower temperatures closer to the application. For test specimens with a high volume- to- surface area ratio, the diffusion of oxygen or ozone into the elastomer can be a limit- ing factor for the destruction of the elas- tomer matrix and the associated ageing processes. For this reason, thick elastomer components often age much more slowly in practice than thinner components. Ozone ageing is a special form of ageing. The well-known cracking of stretched rubber parts exposed to the weather is mainly caused by the ozone present in the air, but artificial sources such as laser printers or disinfection devices are also responsible for damage. Methods for testing ozone resistance are described in DIN ISO 1431-1. SERVICE LIFE Static permanent load and permanent deformation If an elastomer component is deformed to a constant thickness, a certain amount of deformation remains after relaxation. Determined in the test according to DIN ISO 815 (compression set) and stated as a percentage of the original deformation, this residual deformation is called com- pression set. The deformation is strongly dependent on temperature and duration. At lower temperatures the influence of viscoelas- ticity predominates, at higher tempera- tures the influence of ageing. 158

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8. Testing methods In certain cases, the compression set pro- vides direct information on the function of sealing elements, e.g. for O-rings. How- ever, measurements are often only avail- able for a few ageing times and at one temperature. No service life estimate can be made here. The method of compressive stress relax- ation is better suited for estimating the service life (DIN ISO 3384-1); it specifies the decrease in contact pressure over time of a constantly deformed seal, a criterion that is more important for tight- ness. In addition, this method can be used to determine an actual service life estimate, as shown in the previous section. In combination with the corresponding component simulation, even the areas particularly affected by ageing can be determined and optimized. If rubber-elastic parts are under constant load instead of constant deformation (e.g. main force connection), the defor- mation continues (no limiting stop). This is referred to as creep. Stress relaxation and creep are related phenomena with the same causes. If the test temperatures are below the maximum permissible con- tinuous operating temperature of the base polymers, compressive stress relax- ation and creep follow an approximately logarithmic time law (→ Fig. 58). Dynamic stress, fatigue and attrition The destruction of rubber parts is far more frequently due to dynamic stress than to a single exceeding of the strength or elongation limits. Constant repetitive deformation damag- es the material due to internal friction, which can initially cause small cracks that grow and eventually lead to breakage. This effect is comparable to a paper clip deformed by bending. A single bending process may not affect the strength. But after several bending processes, the ma- terial breaks. Standardized methods for test conditions are defined in DIN ISO 132 and 53533, for example. Wear resistance This property, which is important for fric- tional loads, also depends to a large extent on the operating conditions, such as the type of lubrication, material and rough- ness of the mating surface, sliding speed, slip, contact pressure and temperature. Wear tests should therefore only be car- ried out with the finished product and as close to practical conditions as possible. Material models The mechanical, thermal and dynamic characteristic values determined form the basis for the development of material models. In contrast to metallic and ceram- ic materials, for example, there is no linear relationship between stress and strain in elastomers. Consequently, it is not suffi- cient to use "simple" linear-elastic material models for simulations, but rather special models, so-called "hyper- elastic material non-aged elastomer without ozone protection agent with ozone protection agent Fig. 59 Damage to the elastomer due to exposure to ozone I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 159 X E D N I

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Materials and Process Engineering models," are used for this purpose. In ad- dition to the statically non-linear behav- ior of elastomers, the stiffness of the ma- terial must be taken into account as a function of the load velocity. For this purpose, Freudenberg has developed op- timized material models that remain valid even with large material deformations (> 150%). Additional information from component analyses and ageing tests leads to com- plex simulations that provide a compre- hensive picture of the service life of elastomer seals. Simulations with corre- sponding FEM models are used for the topology and design optimization of me- chanically loaded components, taking into account moderate non-linearities and the safeguarding of the component function. For further information, please contact TSI. Permeation The transport of gaseous or liquid sub- stances through materials in a solid ag- gregate state, known as permeation, is of great importance in a wide range of tech- nical applications. In addition to the well- known phenomenon of compressed air escaping from car or bicycle tires, plastic beverage bottles, for example, should Material Play-circle  Permeation and explosive decompression Adsorption Desorption Diffusion Diffusion Fig. 60 Permeation process 160 also allow as little of the CO2 dissolved in the liquid to escape as possible. The de- mand for ever lighter components and improved sealing and membrane systems to protect the environment requires knowledge of the transport processes in the materials used. For example, CO2 is increasingly being used as an operating medium for air conditioning systems in the automotive sector. Due to the high solubility of CO2 in many elastomers and because of the wide temperature range in which the functionality of the sealing system must be guaranteed, this is an ex- tremely demanding application area for elastomer seals (see also → “9. Damage analysis – Explosive decompression”, page 173). The actual permeation process (from the Latin permeare: to pass through) is divided into three sub-steps (→ Fig. 60): y dissolving the medium in the material y the diffusion of the medium through the material y the desorption of the medium from the material As mentioned earlier, the permeation co- efficient depends on various factors. As a material constant, it depends on the material. In elastomeric materials, the polymer used is the parameter that determines the permeability and must be taken into account in sealing issues, in addition to the suitability of the material (resistance). In addition to the base poly- mers, the filler can also influence the media permeability within certain limits. The material dependence of the perme- ation coefficient at a measuring temper- ature of +80 °C is shown in → Fig. 61 a–d.

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8. Testing methods Influence of temperature on permeation VMQ TPE EPDM FKM PTFE NBR ECO CIIR Test gas: Nitrogen 20 30 40 50 60 70 80 90 100 Temperature [°C] ] ) r a b h ² m m ( / ) m m ) T P N ( ³ m c ( [ P 800 600 400 200 100 80 60 40 20 0 Influence of polymer on permeation Test gas: Nitrogen T= +80°C ] ) r a b h ² m m 1000 100 ( / ) m m ) T P N M V E - V Q P T P E M D M K F E F T P R B N O C E C II R ( ³ m c ( [ P 10 1 0.1 I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P Fig. 61 Fig. 61a Influence on permeation Fig. 61b Influence on permeation ] ) r a b h ² m m ( / ) m m ) T P N ( ³ m c ( [ P 50 40 30 20 10 0 Influence of fillers on permeation HNBR 10 phr filler 30 phr filler 40 phr filler Test gas: Nitrogen ] ) r a b h ² m m ( / ) m m ) T P N 30 40 50 60 70 80 Temperature [°C] ( ³ m c ( [ P 180 160 140 120 100 80 60 40 20 0 Influence of medium on permeation NBR T= +80°C Nitrogen i O xygen C arbon dioxide H eliu m H ydro g e n Fig. 61c Influence on permeation Fig. 61d Influence on permeation Examples were taken from the various polymer groups, whereby a different mixture structure also leads to different permeation values. Materials with low permeation values, such as chloro-isobu- tene-isoprene rubber (CIIR), ethylene oxide-chloromethyloxirane rubber (ECO) or nitrile-butadiene rubber are contrasted with highly permeable materials such as EPD M (terpolymer of ethylene, propylene and a diene), TPE or VMQ (silicone rubber). Materials made of VMQ stand out here in particular – their gas permeability is around more than an order of magnitude higher than that of all other rubbers. The application temperature also plays an important role in permeation. Depending on the material, the permeation coefficient changes by a factor of more than 10 be- tween +20 °C and +80 °C. The only excep- tions are silicone rubber and Teflon, whose curve gradients are lower. Higher perme- ation coefficients at high temperatures do not necessarily result in a higher coefficient at room temperature. In the case of ECO and FKM (fluororubber), the curves intersect at +50 °C due to the different gradients. In addition to the temperature, the gas passing through also has a significant in- fluence on the permeation coefficient. S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 161 X E D N I

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Materials and Process Engineering Small molecules, such as helium or hydro- gen, migrate through the material faster than oxygen or nitrogen. → Fig. 64 shows an example of the gas type dependency for an NBR material. Other materials be- have similarly, although the ratios be- tween the values of the individual gases can vary considerably. The behavior of elastomers compared to carbon dioxide is quite interesting. Although CO2 is a relatively large gas mol- ecule, the speed at which it migrates through the elastomer is greater than that of helium or hydrogen. This may be due to the chemical similarity of CO2 and the elastomers. The known high sol- ubility of carbon dioxide in the material confirms this assumption. This chapter has dealt with the basic material tests. For special applications, other physical properties such as thermal expansion, frictional behavior, electrical properties, permeability to gases or liq- uids may be of importance. Many of these properties can only be determined in complex special tests. These tests are only carried out if necessary, for example to determine the exact cause in the event of damage. If you have any questions about tests other than those presented, please con- tact the test specialists at FST. 162

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9. DAMAGE ANALYSIS 9. Damage analysis I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I Even if products and components are constructed to the best of our knowledge and taking the latest findings from devel- opment, design and use into account, unexpected damage occurs time and again. It can occur in all product phases (development, storage, production, oper- ation, ...) and is often associated with costly production downtimes and recalls. If people are also at risk, additional dam- age to the company's image is to be feared. Research and development must also in- clude a detailed damage analysis or root cause analysis and the definition of suita- ble remedial measures. VD I 3822 provides a guideline for the systematic processing of damage cases. This guideline was de- veloped by the VD I in cooperation with companies and institutes (including FST) and has been successfully applied at Freudenberg since then. Rubber as a material is a complex subject area, especially in the case of damage anal- ysis, in which interdisciplinary cooperation is of particular importance. The chemical reactions that take place during the vulcan- ization process as well as the emission and absorption of various substances during production, storage and use often make it difficult to interpret the results of chemical analysis methods and physical measure- ments. Furthermore, changes in the cross- link structure and/or the widely cross-linked macromolecules themselves can occur dur- ing use. In addition to chemical and physical analyses, microscopic and radiographic methods are often used to perform damage analysis, in fractographic examinations, for example. Finally, it should also be men- tioned that the method of correct photo- graphic documentation is also part of the basis of efficient damage analysis. 9.1 DAMAGE ANALYSIS PROCESS A systematic approach is essential in damage analysis. At Freudenberg, dam- age analysis is carried out in accordance with VD I guideline 3822. A visualization of the procedure is shown in → Fig. 62 dargestellt. If there is a leak in the system and a de- fective seal is removed, the problem of- ten appears simple, the defective sealing element is assumed to be the cause and submitted for analysis. However, the re- ality is often much more complex. In or- der to successfully drive the damage anal- ysis forward, it is necessary to take a holistic view of the failure process and Damage description Inventory of damage Damage hypothesis(es) Instrumental analysis Result evaluation and interpretation Cause(s) of damage Remedial measure(s) Damage report Evaluation Failure analysis Management system R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P Fig. 62 Damage analysis process 163 X E D N I

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Materials and Process Engineering Causes of errors F a u m l t y a t e r i a l c s i e g s s i n g n F F M F a a a u u u e p r l t d l t l o c h l t e h a o y y a a n d y n d i c l i a n l g Tribological stress Climate-stress Media-related stress Thermally induced stress Mechanism of the error Other problems Description of the error General evaluation Fig. 63 Ishikawa diagram for formulating possible damage hypotheses the product - from development to inter- mediate steps such as production and quality control (and much more) through to the application with all its influences. It often makes sense to involve experts from the fields of material, process, design and application technology. The first step in describing damage is documentation with the help of images and sketches. If samples are destroyed in further analyses, the original condition can be viewed again, at least virtually, retrospectively. This includes a descrip- tion of the samples with all of the abnor- malities such as cracks, deformations, discolorations, etc. Finally, more detailed macroscopic examinations are used to document and evaluate characteristic damage phenomena in order to determine whether the same damage mechanism is present in all samples. Information on the samples and the accompanying cir- cumstances is collected in the inventory. This includes the product phase (field failure, development, test bench), the product history (how long has the product existed? Are similar failures known?) and the failure history (number of failed parts, localization of the dam- age?), see also → chapter “Services” from page 7). Finally, one or more damage hypotheses are drawn up using the information from the damage description and inventory as well as knowledge of damage mecha- nisms and experience from other damage cases. The Ishikawa diagram shown in → Fig. 63 serves as a template for formulating the damage hypotheses. The damage hypotheses serve as a guide- line for the analyses. Particularly in the event of damage, it is important to choose the sequence, location and type of preparation and analysis methods carefully. In addition to the failed products, new and good parts are always required for comparative analyses. Map-Marker-Exclamation Services and Consulting 164

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9. Damage analysis Close cooperation within the interdisci- plinary team is required when evaluating and assessing the results with regard to the claim. If results do not confirm the hypothesis or unexpected results occur, the analysis plan must always be flexible enough to allow other methods to be used for verification. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P DESIGN ERRORS MECHANICAL THERMAL LOAD LOAD MEDIA EXPOSURE CLIMATIC STRESS S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 165 X E D N I MANU- FACTURING ERRORS Vulcanized elastomer particles MATERIAL ERRORS Material mix-up Wrong raw material quantity Contamination of raw materials or the compound Slit extrusion Cracks Cracks Swelling Hot cracks Offset Delamination Cracks, tears Malfunction with an undamaged component Softening Scratches/ scoring Geometry changes/ permanent deformation Extraction Replacement of additives with compo- nents of the medium Oriented cracks due to ozone exposure Non-oriented cracks due to exposure to UV light Frosting Insufficient mixing Gas bubbles Air/gas inclusions Abrasion/wear Hardening Reaction of additives with media Softening, hardening, stickiness Use of incorrect- ly stored or expired raw materials or compounds Flow errors Flow errors Charred surface Incompatibility of components Under-/over- vulcanization Color change Cracks with crack exit in the material interior Softening, hardening Porosity, cracks Tab. 10 Common damage phenomena and causes

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Materials and Process Engineering 9.2 TYPICAL DAMAGE PHENOMENA, CAUSES AND MECHANISMS Some common damage phenomena and causes are summarized in → Tab. 10. At first glance, it is clear that many damage phenomena (e.g. cracks, hardening, softening) can have different causes. For example, a component with many small cracks may have been damaged both by mechanical impact and by ozone expo- sure. This shows that damage patterns are often deceptive and an analysis can- not be carried out on the basis of the first visual impression alone. The relevance of the phenomena found must always be assessed when determining the cause of damage. In other words: Is a phenomenon the cause of the failure, a contributing factor or not the cause? Some of the typical damage phenomena and their underlying mechanisms are ex- plained below using selected examples. MATERIAL DEFECTS During compounding, the raw rubber and additives such as fillers, plasticizers, cross-linking chemicals, anti-ageing agents and much more are brought together. This is followed by the shaping and vulcaniza- tion process. Material defects are consid- ered here to be defects that are caused by compounding, transportation and storage of the elastomer mixture. Par- ticularly in non-certified mixing plants, materials may be mixed up or additives may be added incorrectly, which can result in deviations in the properties of the material from the specification. Contam- ination of the raw material or compound during transport, storage and processing is also possible. Examples of this are shown in → Fig. 64 and → Fig. 65. The de- fects shown can have an optical effect (if the contamination is visible on the surface of the component), lead to defects such as cracks or, depending on the application of the product and the size of the contamination, cause no change in properties. Unfortunately, it is not possi- ble to make a general statement on the probability of damage based on particle sizes. Whether an inclusion causes a crack depends not only on its size and compo- sition, but also on the environmental con- ditions (component geometry, load, etc.). Fig. 64 SEM image of a metal particle (light) in the elastomer matrix Fig. 65 Microscopic image of a fiber on the surface of a light-filled vulcan- izate 166

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9. Damage analysis Map-Marker-Exclamation “Zero-defect strategy” in the manufacturing process Fig. 66 Poor carbon black distribution Fig. 67 Good carbon black distribution Another example of material errors is insufficient mixing. The effects this can have are shown in → Fig. 66 and → Fig. 67. For this purpose, the starting materials specified in a formulation were mixed in two batches, but with different mixing times. After vulcanization, cold thin sec- tions were prepared and microscopically examined under transmitted light (the dark spots are carbon black agglomerates). As mentioned above, elastomeric mate- rials are made up of a wide variety of components that are not always compat- ible with each other. This can lead to the finely dispersed components in the mix- ing process later coalescing into larger domains (coalescence) or migrating out of the mixture and causing a change in the physical properties. In the case of some ingredients, this is quite desirable, if, for example, anti-ageing agents migrate to the surface of the product and protect the component there through a chemical reaction. However, this can lead to com- plaints in applications with contact to foods or visually demanding components. MANUFACTURING ERRORS When manufacturing and selecting the appropriate sealing solutions, the utmost care must be taken in order to meet the most diverse requirements of the many different areas of application. This makes it all the more important to have a compe- tent partner who already safeguards the highest quality during the manufacturing process with a "zero-defect strategy." Freudenberg Sealing Technologies has been pursuing precisely this approach for many years and is therefore in a position to supply you with the best and faultless quality in the field of sealing technology – precisely tailored to your requirements. Despite all due care, errors can occur during the manufacturing process, e.g. during shaping, vulcanization or post- processing, which are discussed below. Errors can only be recognized and avoided through knowledge of possible sources of error. Binding seam Confluence points in the mold can develop into visually visible defects, so- called weld lines. This can be caused by inadequate process parameters (e.g. in- sufficient filling volume, excessively high compound or mold temperature), but also by foreign substances or release agents. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 167 X E D N I

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Materials and Process Engineering elastomer matrix. An example is shown in → Fig. 70. Such a defect pattern is caused by too long a mixing or storage time, too high a compound or tool tem- perature or dead spaces in tools or burrs from previously produced parts. Over- or under-cross-linked material If the vulcanization conditions are not selected correctly or the quantity of cross-linking chemicals is not optimal, this leads to deviations in the material properties from the target state or spec- ification. In particular, deviations in the vulcanization temperature or in the tem- perature distribution within the mold quickly lead to defects. It must be en- sured that the vulcanization conditions are correct at all times. The temperature sensitivity of a peroxide cross-linked HNBR compound is shown here as an example. Even a temperature change of +10 °C can result in a 30 % lower degree of polymerization. The physical and ageing properties can change fundamentally. Hot cracks → Fig. 71 shows examples of the me- chanical properties of a vulcanizate in dif- ferent temperature ranges. The signifi- cant change in strength and elongation at break at higher temperatures can be a potential source of error. When the mold is opened after vulcanization, expansion or tensile forces can lead to so-called hot cracks in the component. The resistance to mechanical influences is massively reduced. Sharp edges can also cause damage here. Bubble formation Insufficient venting of the material during filling or residual moisture in the rubber Fig. 68 Binding seam: top view under a scanning electron microscope Fig. 69 Binding seam: Macroscopic image of a thin section in transmitted light Fig. 70 Scorched elastomer particle (macro- scopic image of a thin section in transmitted light) Vulcanized material If elastomer particles were already vulcan- ized in the mold before the actual manu- facturing process, they do not or only in- sufficiently crosslink with the surrounding 168

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9. Damage analysis s e i t r e p o r p l i a c n a h c e M 75 A 180% 21 MPa Hardness Elongation at break 60 A 60% Tensile strength 3,5 MPa -50 0 RT 50 100 150 200 250 Temperature [°C] Fig. 71 Mechanical properties at different temperatures compound itself lead to the formation of bubbles during the manufacturing process. The air can also be pushed in front of the flow front and collect in the area of the confluence point. Bubbles, porosities or smooth indentations form along the sealing surface. The phenomenon of gas bubble formation occurs primarily with large-volume components. Delamination In the case of delamination damage, the elastomer material has a layer-like sepa- rated structure (flaky). Possible causes in- clude air inclusions (→ Fig. 73), especially in the case of gas-tight elastomers or large-volume components, release agents or foreign material between the flow fronts (→ Fig. 74). Fig. 72 Gas bubbles in the cross-section of Fig. 73 Delamination (Image: Freudenberg a voluminous component Technologie Innovation, order) I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 169 X E D N I

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Materials and Process Engineering Fig. 74 Delamination (VDI guideline for production, Freudenberg Technol- ogie Innovation) Fig. 75 Oﬀset Material testing Oﬀset Tool parts are worn or incorrectly fitted and no longer close symmetrically. This results in the formation of a shoulder in the parting line area. Errors in tool dimen- sioning (design errors) can also cause this form of damage. Despite an otherwise perfect condition, the component often cannot perform the sealing task. DESIGN ERROR Gap extrusion Gap extrusion is the migration of the seal into the sealing gap facing away from the pressure side. This type of damage also occurs, for example, due to design errors in the sealing gap, if there is too little opportunity for temperature expansion or if there is too much volume swelling. In Pressure p Pressure p Fig. 76 Principle sketch of gap extrusion 170 the static case, this leads to the formation of the typical extrusion flag shown in → Fig. 77. Under dynamic load, the elas- tomer is "nibbled off" (→ Fig. 78). Errors in the choice of material (insufficient deformation resistance) or the ingress of media into the material can also cause or promote the damage phenomenon. MECHANICAL STRESS According to the VD I guideline for damage analysis VD I 3822, sheet 2.2.5, damage caused by mechanical stress includes damage that occurs during use or assem- bly. In addition to the type of load (ten- sion, compression, torsion, buckling, etc.), the loading speed is important, especially at low temperatures (see also "thermal load"). If the material cannot follow the movement of the limited components, this can lead to leakage of the system or, in a glass-hard state, to the destruction of the component. Mechanical overload/fatigue Even if a mechanical load under cyclic stress is far below the maximum elonga- tion and strength of the material, the mechanical properties will change as a result of permanent swelling stress. This

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9. Damage analysis Fig. 77 Gap extrusion – static application Fig. 78 Gap extrusion – dynamic application is referred to as fatigue. This results in chain fractures on a microscopic level or, on a macroscopic level, many small cracks in the material, which can ultimately lead to failure. Permanent deformation or abrasion can also occur as a result of dynamic stress. Mechanical injury Scratches, scoring and cracks are often caused by sharp edges or unsuitable tools, during removal from the mold, for example. Exemplary damage patterns for mechanical damage are shown in the SEM images in the following figures (→ Fig. 79 und → Fig. 80). Abrasion The importance of the individual design of seals is shown by the abrasion behavior when the surface quality changes. Even the smallest changes in the surface treat- ment method can result in premature fail- ure of a seal. It is therefore highly inadvis- able to simply transfer a sealing solution. Cleanliness is also the top priority during assembly, as chips, dust and dirt can lead to the same effect and thus have an enor- mous impact on the longevity of the seal. In general, it can be said that although there are special formulations for elasto- mers that show improved abrasion be- havior, only lubrication prevents rapid wear in dynamically used seals. Twisting This fault pattern describes cracks in the seal caused by torsional stress. If the seal is twisted, it tears after frequent load changes. This is caused by a dynamic load in which one side of the seal remains immobile or slides, while the other side adheres and is thus twisted. Frequent changes of direction in particular lead to material fatigue – the seal shows typical spiral cracks. Here it is important to avoid possible eccentricity, i.e. the distance be- tween the center of the groove and the symmetry axis of the component. Eccen- tricity causes uneven load points, e.g. in the event of pressure fluctuations, which increases the probability of twisting. Good surface quality and good lubrica- tion conditions also help. In addition, the effect may occur less frequently with thicker cords (see also → chapter „Static Seals – 11. Technical Support – Twisting“, page 625). I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 171 X E D N I

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Materials and Process Engineering Chemical media Biological media Radiation ? Temperature Natural load Mechanical load THERMAL STRESS Low temperatures → Fig. 81 shows the behavior of the elas- tomer, thermoplastic and duromer materi- al classes schematically over temperature. Elastomers are solidified like glass below the glass transition temperature (Tg). In this area, even low loads can lead to failure through breakage. In addition, the modulus increases sharply even before the glass transition point is reached, so that a change in resistance during excitation of dynamic seals or diaphragms is to be expected. The entropy-elastic behavior typical of elastomers can be seen above the glass transition. This is the actual area of appli- cation for elastomer materials. However, the material does not only stiffen when the temperature is lowered. Even at temperatures above the glass transition Fig. 79 Damage pattern for mechanical Fig. 80 Damage pattern for mechanical damage, SEM image damage, SEM image 172

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9. Damage analysis temperature, high deformation speeds can result in the polymer chains not being able to follow the deformation quickly enough. In addition to catastrophic failure, this be- havior also leads to other malfunctions such as leakage. This is shown in → Fig. 84 using the sealing function of an O-ring. The O-ring can follow a dynamic load/ opening of the mating surface at room temperature quickly enough and prevent a gap from developing. If the same happens at temperatures close to the glass point (or at very high frequencies), the mobility of the polymer chains is restricted to such an extent that the seal cannot follow suf- ficiently quickly and leakage can there- fore occur. High temperatures and media stress See → “Heat resistance, aging behavior”, page 156. EXPLOSIVE DECOMPRESSION If the seal is destroyed by a sudden drop in high gas pressure acting on the seal, e.g. due to a pipe bursting, this is known as explosive decompression. This type of damage is caused by gas dissolved in the seal. The higher the gas pressure, the greater the amount of dissolved gas in the seal. If there is no counter-pressure (e.g. due to a pressure drop in the system), the dissolved gas strives to leave the seal, similar to the carbon dioxide in a bottle of water. In the elastomer, this process is linked to the diffusion speed, and there- fore only takes place slowly. If the result- ing internal pressure exceeds the strength of the material, destruction occurs due to the formation of bubbles or cracks in the seal. The larger the volume of the compo- nent in relation to its surface area, the more likely it is that the defect will occur. 10.000 ] a P M [ G 1.000 100 10 1 glass-elastic area rubber-elastic area TG –150 –100 –50 0 +50 +100 +150 +200 +250 Temperature [°C] Fig. 81 Modulus behavior of polymeric materials over temperature Duromer Thermoplast Elastomer I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 173 X E D N I

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Materials and Process Engineering Play-circle  Permeation and explosive decompression Fig. 82 Damage due to excessive mechan- ical stress at temperatures close to the glass transition The error depends heavily on the material and type of gas. CLIMATIC STRESS Hydrolysis Hydrolysis is the cleavage of a chemical bond by the presence of water molecules. In the process, hydrolysis-sensitive groups such as esters, amides, etc. are cleaved. As a result, the polymer chains are broken down and the material properties are changed. In the presence of acids and bases, the process is catalyzed, i.e. accelerated. As acid groups are formed during hydrolysis, these accelerate further by autocatalysis. +23 °C 0 °C Fig. 84 Temperature-dependent reset behavior (from VDI Standard 3822, Part 2.2.7) 174 Fig. 83 Damage pattern for explosive decompression The reaction rate increases at higher tem- peratures. Furthermore, at higher tem- peratures, more moisture can be ab- sorbed from the air, which can also lead to accelerated hydrolysis. This effect is par- ticularly significant for plastics (e.g. polyes- ter, polyamide ....) and polyurethanes. Elas- tic materials are less affected. Exposure to UV light High-energy light leads to changes in the polymer chains of the materials. Elastomers that contain double bonds in the main chain (R family) are particularly susceptible. Compared to translucent plastics, which are also damaged within their volume, elastomers often only suffer damage in the area near the surface due to their filler con- tent. When components are stretched, surface cracking occurs perpendicular to the direction of loading. In contrast to damage caused by ozone, however, fine non-directional crack structures also oc- cur, and without pre-exposure only these. One speaks of a so-called weathering skin (crazing, "elephant skin"). Softening or hardening of the surface can also occur, especially in the presence of acid. Even if the defect initially only occurs on the surface, classic "tearing," which is known

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9. Damage analysis Fig. 85 Surface changes due to light or UV radiation at different magnifications to require lower forces, can lead to the destruction of the elastomer parts. Color changes due to light can also occur. Exposure to ozone Elastomers with an unsaturated main chain are susceptible to a special form of oxygen molecule, ozone, as well as being less resistant to atmospheric oxygen. A hardened layer forms on the surface. When polymer chains are under mechan- ical tension, chain scission occurs with the formation of carbonyl oxides and car- bonyl compounds. Macroscopically, the cleavage of the molecular chains leads to the cracks that are typical of ozone expo- sure and run perpendicular to the direc- tion of elongation. The ozone molecule attacks in the area of the double bond (→ Fig. 88), whereby a so-called primary ozonide forms first. The unstable ring structure rearranges to form the ozonide in the unstressed state. Cracking occurs above a certain critical elongation (depending on the material and environmental conditions) and is in- tensified with increasing elongation of the elastomer (→ Fig. 87). 5% no cracks 10% cracks 20% cracks 25% cracks n o i s n a p x e f o n o i t c e r i D Fig. 86 Oriented cracks caused by ozone exposure (image Freudenberg Technologie Innovation) Fig. 87 Ozone cracks due to expansion stress I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 175 X E D N I

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Materials and Process Engineering Attack on a double bond R1 H C = C R2 R2 Rubber (O3) + O + O – O W ith o ut stretc hin g O O O R1 R2H R2 Primary ozonide With stretching Fig. 88 Ozonization R1 R2 O H O R2 O Ozonide (hardened layer – crazing) R1 H C = O – O + O + C(R2)2 Cracking with “critical elongation” 176

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10. DEFECT CHECKS 10. Defect checks Defect checks are common in the sealing industry, whereby a distinction is made between manual and machine checks. However, the advantages and disadvan- tages of both options must be taken into account. Manual inspection may allow for more intensive testing of the component, but can be subjectively influenced. If the in- spection intervals are too long, there is also a risk of material fatigue. A machine-based test is also not 100% er- ror-free, as the boundary between passing and failing must be defined beforehand. If this is too low, more faulty parts reach the customer; if the limit is too high, the pseudo scrap increases. Another disadvantage of automatic con- trol is that faults have to be taught in. Skilled personnel are more flexible in this respect when it comes to new error pat- terns. Inspection is primarily possible for exter- nally visible defects (surface). Other pos- sibilities: X-ray, CT, density, measurements, etc. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 177 X E D N I

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Materials and Process Engineering 11. PROPER STORAGE The correct storage of elastomer compo- nents has a major influence on their durability and is therefore just as much a part of handling as proper assembly and installation. Components can be damaged by improper storage, which in the case of seals can lead to premature or immediate failure of the seal. STORAGE CONDITIONS The storage temperature must be below +25 °C; the elastomer molded parts must be stored away from direct heat sources and may not be exposed to direct sunlight. Care must also be taken to ensure that the humidity does not lead to condensation when the temperature in the storage room changes. The effects of light, UV ra- diation, ozone and ionizing radiation must also be ruled out. Packaging Materials for packaging such as containers, bags or films may not contain any sub- stances that promote premature ageing of the components. On the other hand, the packaging may not absorb any of the elas- tomer's ingredients. Suitable packaging materials include lami- nated kraft paper, aluminum foil or opaque PE film (min. 0.075 mm thick). The packaging must be labeled as follows so that the parts can be precisely assigned later if necessary: y Part/article number O-ring manufacturer y Description of the polymer 20-2/335674 72 NBR 872 y Quarter and year of manufacture of the elastomer part 1/22 y Classification of the elastomer Group 2 10 pieces Freudenberg (→ Tab. 11) y Number of packages y Name or trademark of the manufacturer Elastomer products are divided into three groups based on their maximum permis- sible storage time (→ Tab. 11). Extensions to the storage period are pos- sible under certain circumstances, but always require consultation with the rele- vant specialist department that will carry out the necessary checks and ultimately 1. STORAGE TIME IN YEARS 1. EXTENSION IN YEARS Group 1 NR, AU, EU, SBR Group 2 Group 3 NBR, HNBR, ACM, AEM, XNBR, ECO, CIIR, CR, IIR FKM, VMQ, EPDM, FVMQ, PVMQ, FFKM, CSM Tab. 11 Recommended storage times for elastomers 5 7 10 178 2 3 5

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11. Proper storage Map-Marker-Exclamation Only one-time extension for shaft seals decide whether the products can continue to be used or must be disposed of. Caution! Only one extension is permit- ted for shaft seals, after which the parts must be scrapped. SUGGESTIONS FOR THE ASSESSMENT OF ELASTOMER COMPONENTS AFTER THE INITIAL STORAGE PERIOD y Testing according to the respective product specification There are product specifications that provide for certain tests after the expiration date. If the corresponding product specification does not contain such information, the following check is necessary: y Visual inspection Each part or component in a repre- sentative sample is to be checked for the following characteristics: • Changes in the condition of the sur- face, such as hardening, softening, stickiness, discoloration or soiling • Additional tests: Microhardness, density, functional dimensions: sealing lip, dust lip, inner diameter and radial force The tested characteristics of the stored parts or components must be document- ed in an appropriate manner. If the number of measured components permits, the reasonable confidence interval around the mean value of each test performed must also be specified. y Each recording must contain the fol- lowing information: • the number of parts or components stored, the date of first packing, the date of loading • the date of each subsequent repack- aging • the manufacturer's batch number, • Permanent deformation, such as if available folds or flat spots • Mechanical damage, such as cuts, cracks, abraded areas or detached layers • Crack formation on the surface, ob- served under a magnifying glass with 10x magnification • the number of parts or components that have been tested I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 179 X E D N I

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Materials and Process Engineering 12. CHEMICAL RESISTANCE The information contained in the follow- ing table has been compiled on the basis of our own tests, recommendations from our suppliers and reports from our cus- tomers. The latest version of this summa- ry can only be found on our homepage. This information can only serve as a rough guide. It is not readily transferable to all operating conditions. Even within the material classes, there can be serious differences due to different mixture com- positions. Given the large number of factors affect- ing the seals and molded parts, chemical resistance is a very important but only a partial aspect of the overall operating conditions. The following factors should always be taken into account when se- lecting Freudenberg Sealing Technologies materials and the shape of the sealing element: y heat and cold resistance y static or dynamic load y type of material of the machine parts to be sealed The elastomers listed in → Tab. 12 are named with their chemical designations and the abbreviations defined in ASTM D 1418. ELASTOMERS LISTED IN THE RESISTANCE TABLES ACM Acrylic rubber AU CR Polyurethane Chlorobutadiene rubber CSM Chlorosulfonated polyethylene EPDM Ethylene propylene diene rubber FFKM FKM Perfluoro rubber Fluororubber FVMQ Fluorosilicone rubber HNBR Hydrogenated acrylonitrile butadiene rubber y surface quality of the metal parts or IIR Butyl rubber plastic parts y for rotating seals: Speed y for axially moving parts: Stroke length and stroke speed y for other dynamically loaded seals: Load frequency and amplitude If no special information is provided in the tables, commercial and the usual purity, concentration and specified tempera- tures for the respective media are to be assumed. In case of doubt, especially for untested or new applications, we recom- mend that you consult us so that special tests can be carried out if necessary. NBR Acrylonitrile butadiene rubber NR Natural rubber PTFE Polytetrafluoroethylene SBR Styrene-butadiene rubber VMQ XP Silicone rubber Fluoroprene XP Tab. 12 Material abbreviations Chemical Resistance Guide 180

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12. Chemical resistance In this table and in the following resist- ance overviews, some common elastomer types are missing, e.g. BR, ECO, CIIR, BIIR, EVM, AEM and PVMQ. Analogies are possible in many cases. Fluoroprene XP is a class of premium sealing materials from Freudenberg Sealing Technologies. If you have specific questions or uncer- tainties, please consult the relevant spe- cialist department. The tables on the following pages com- pare the materials listed in → Tab. 12 with regard to their resistance to media at the respective test temperature (col- umn 2). You can find the latest information on resistance online in our Chemical Resist- ance Guide. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 181 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Acetaldehyde with acetic acid, 90/10% Acetamide Acetone +20 D G D C C B D D D C D C B C D F +20 G G G F F B G F F F F G B G G F +20 D D D F B B D D D B D B B B D F Acetophenone +20 G G G F F B G G G F G G B G G F Acetylene Acetic ester Acetic acid, aqueous, 25 to 60% +60 B F B B B B B B B B B B B B B B +20 G G G C C C D G D F D D B D G G +60 G G G B B B G G D B D D B D G B Acetic acid, aqueous, 85% +100 G G G F F B G G D F D D B D G B Acetic anhydride +20 G G B B B B D G D B D C B B G C Acetic anhydride +80 G G C F F C D G D F D D B C G F Acrylonitrile +60 G G D G F B D D D D D D B D D F Acrylic acid ethyl ester +20 D D G G F B D D D C D G B G D F Adipic acid, aqueous +20 F F B B B B B F B B B B B B F B Air, oily Air, pure Aircraft engine fuels JP3 (MIL-J-5624) Aircraft engine fuels JP4 (MIL-J-5624) Aircraft engine fuels JP5 (MIL-J-5624) +80 B B B B D B B B B D B D B C B B +80 B B B B B B B B B B B B B B B B +20 C C D D D B B B C D B D B D D B +20 C C D D D B B C C D B D B D D B +20 C C D D D B B C C D B D B D D B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 182

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12. Chemical resistance MEDIUM Aircraft engine fuels JP6 (MIL-J-25656) °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X +20 C C D D D B B C C D B D B D D B Alum, aqueous +60 G D D B B B B G D B D C B C G B Alum, aqueous +100 G G B B B B B F B B B D B B F B Allyl alcohol +80 G D C C B B D G C B C B B B G F Aluminum sulfate, aqueous +60 G D C B B B B F B B B B B B F B Aluminum sulfate, aqueous +100 G D C B B B D F B B B C B B F B Ammonia, 100% +20 G D C B B C D G C B C B B B G G Ammonia water (ammonia) +40 D D C B B B D C B B B B B B C F Ammonium acetate, aqueous +60 G D C B B B D F B B B B B B F F Ammonium carbonate +60 G D C B B B D F B B B B B B F F Ammonium chloride, aqueous +60 G D C B B B B F B B B B B B F B Ammonium fluoride, aqueous +20 G G C B B B B B B B B B B B B B Ammonium fluoride, aqueous +100 G G C B B B D F B B B D B B F F Ammonium nitrate, aqueous +60 G D C B B B B F B B B B B B F B Ammonium nitrate, aqueous +100 G G C B B B D F B B B D B B F F Ammonium phosphate, aqueous +60 G D C B B B D F B B B B B B F F B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 183 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Ammonium sulphate +60 G D C B B B B F B B B B B B F B Ammonium sulphate +100 G D C B B B D F B B B D B B F F Ammonium sulphide, aqueous Ammonium sulphide, aqueous Amyl acetate Amyl alcohol Aniline +60 G D C B B B B F B B B B B B F B +100 G D C B B B D F C B C D B C F F +20 G G G F B B D G D B D B B D G F +60 G D C B B B D F C B C B B B F F +60 G D D G G B D D D G D D B D D G Aniline chlorohydrate +20 G D C C C B B F C C C D B D C B Aniline chlorohydrate +100 G D F G G B G G D G D D B D G G Anisole Anon Anthraquinone sulfonic acid, aqueous +20 G G D G G B G G D G D D B D G F +20 G G D G D B G G D D D D B D G B +30 G D G B B B G G C B C B B B G B Antifreeze (automotive) +60 G D B B B B B B B B B B B B B B Antimony chloride, aqueous +20 B G B B B B B B B B B B B B B B Antimony trichloride, anhydrous +60 G G C B B B G G B B B B B B G F Aqua regia +20 D D D D D B D D D D D D B D D F B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 184

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12. Chemical resistance MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Arsenic acid, aqueous +100 G G C B B B D F B B B D B B F B Arsenic acid, aqueous +60 F D C B B B B F B B B B B B F B Asphalt ASTM fuel A ASTM fuel B ASTM fuel C +100 F G G G G B F G G G G G B G G B +60 C B C C D B B B B D B D B D D B +60 D D D D D B B B C D C D B D D B +60 D D D D D B B C D D D D B D D B ASTM oil no. 1 +100 B C B D D B B B B D B D B D B B ASTM oil no. 2 +100 B C C D D B B B B D B D B D B B ASTM oil no. 3 +100 B C C D D B B B C D B D B D C B ATE brake fluid +100 D G C G B F D B D B D B B B B F ATF oil +100 D C C D D B B B B D B D B D C B Battery acid (sulphuric acid) +60 G D D B B B B G D B D C B C G B Barium hydroxide, aqueous +60 G D B B B B B F B B B B B B F B Barium salts, aqueous +60 G D C B B B B B B B B B B B B B Beef tallow emulsion, sulphurized +20 G G C B D B B C B D B D B D C B Beer +20 B B B B B B B B B B B B B B B B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 185 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Benzaldehyde, aqueous +60 G D D G C B B G D C D C B C G B Benzoic acid, aqueous +60 G D C B B B B B B B B B B B B B Benzene +20 D D D D D B C C D D D D B D D B Benzyl alcohol +60 G D G F F B G C G F G F B F C B Biogas Bisulfite lye Bitumen Black liquor +20 F C B B G B B D B G B D B D B B +50 G D C B B C G F C B C B B B F C +60 G G D G G B B G D G D G B G G B +100 G G C B B B B G C B C C B C G B Blast furnace gas +100 B F C C C B B B C C C D B C B B Bleaching lye +60 G D C B B B C G D C D D B C G B Bone oil +60 B B D D D B B B B D B D B D C B Borax, aqueous +60 G D C B B B B B B B B B B B B B Boric acid, aqueous +60 G D C B B B B B B B B B B B B B Brake fluids (glycol ether) +80 D G C F B F G B D B D B B B B F Bromine, liquid +20 G G D C F F G G D F D D B D G G Bromobenzene +20 G G G G G F F F G G G G B G G F Bromine vapors Bromine water, cold saturated +20 G G D C F F G G D F D D B D G G +20 G G D C F F G G D F D D B D G G B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 186

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12. Chemical resistance MEDIUM Bunker oil Butadiene °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X +60 F G G G G F F F C G C G B G G F +60 G F C D D B B B F D F D B D C B I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H Butane, gaseous +20 B B C D D B B B B D B D B D F B Butanediol, aqueous +20 G F C B B B C F B B B B B B F B Butanediol, aqueous +60 G D B B B F F F B B B C B B F F Butanol, aqueous +20 C B D B B B C B C B B B B B B B Butanol, aqueous +60 G D C B B B G F D B D B B B F B Butynediol +20 G B C B B C C F B B B B B B F C Butter Butter +20 F B B G G B B B B G B G B G B B +80 F F C G G B B F B G B D B D F B Butyric acid, aqueous +20 G F C F F B B F B F B D B F F B Butyl acetate Butyl acetate Butyl alcohol +20 G G D D C B D G D C D C B D G G +60 G G D D D B D G D D D D B D G D +60 G D C B B B G F D B D B B B F B Butylene, liquid +20 F B C G G B B B B G B D B D F B Butylene glycol +60 G B B B B B C B B B B B B B B B Butylphenol +20 D D D D D B C G D D D D B D D B Butyraldehyde +20 G G G C C C G G G C G C B C G B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 187 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Calcium bisulfite, aqueous +20 G B B B B B B F B B B B B B F B Calcium chloride, aqueous +100 G D B B B B B B B B B D B B B B Calcium hydroxide, aqueous +20 G D B B B B B B B B B B B B B B Calcium hypochlorite, aqueous +60 D D C B B B C G D B D D B D G B Calcium nitrate, aqueous +40 G G B B B B B B B B B B B B B B Calcium phosphate, aqueous +20 G F B B B B B B B B B B B B B B Camphor Camphor oil +20 G G C D D B C G B D B D B D G B +20 G G D C D B C G C D B D B D G B Carbon dioxide, dry +60 B F B B B B B B B B B B B B B B Carbon disulphide +20 G D D C D B B G D D D D B D D B Carbon oxide, moist +20 B G B B B B B B B B B B B B B B Carbon oxide, dry +60 B B B B B B B B B B B B B B B B Carbon tetrachloride +60 G G D D D B B G D D D D B D G B Caustic potash solution, 50% +60 D D C B B C D D C B C C B C D C Caustic soda Cellosolve +20 D G C B B B D D C B C C B C D B +20 G G G C C F G G G C G G B G G F Chlorine, liquid +20 G G D C C C C G D C D D B D G G Chlorine, gaseous moist +20 G G D C C C C G D C D D B D G D B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 188

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12. Chemical resistance MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Chlorine, gaseous dry +20 G C D C C C C G D C D D B D G C Chloral hydrate, aqueous +60 G G D C C B C G D C D D B D G B I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H Chloramine, aqueous +20 F F B B B C G F B B B B B B F G Chloroethanol +60 G G D C C C D G D C D D B D G F Chlorobenzene +20 D F D D D C C D D D D D B D D C Chlorobromomethane +20 G G G C C C C C G C G G B G G C Chloroacetic acid +60 G D C B B C G G C B C D B D G D Chlorinated lime, aqueous +60 G D D B B B B G D B D D B D G B Chloromethyl +20 G C D D D B C G D D D D B D G B Chloroform +20 G D D D D B C G D D D D B D G B Chloric acid, aqueous +80 G G D C C B C G D C D D B D G B Chlorosulfonic acid +20 D G D D D F G D D D D D B D D F Chlorinated water, saturated +20 G G D B B B B G D C D D B D G B Chromic acid, aqueous +60 G G D B F B B G D F D D B D G B Chromic acid/sulfuric acid/ water, 50/15/35 % +40 G G D B F B B G D F D D B D G B Citric acid, aqueous +60 G G C B B B H F B B B B B B F B Clophen A types +100 F D D G G B B B D G D D B D B B Clophen T 64 +100 F D D G G B B F D G D D B D C B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 189 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Coconut fat +80 B B C D D B B B B D B D B D B B Coconut fatty alcohol +20 F G B C C B B F B C B C B C F B Coconut oil Coconut oil Cod liver oil +80 F F C G G B B F B G B D B D F B +60 B B C D D B B B B D B D B D B B +20 B B B C C B B B B C B C B C B B Coke oven gas +80 G G D D D B B F D D D D B D F B Copper(I) chloride, aqueous +20 B B C B B B B B B B B B B B B B Copper fluoride, aqueous +50 G G C B B B B F B B B B B B F B Copper nitrate, aqueous +60 G G C B B B B F B B B B B B F B Copper sulphate, aqueous +60 G G C B B B B F B B B B B B F B Cottonseed oil +20 F B C C C B B F B C B C B C F B Cresol, aqueous +45 G B D D D B B G D D D D B D G B Crotonaldehyde +20 G F G B B C D G G B G C B C G D Crude oil +20 B B C C D B B B C D B D B D C B Cyanide, aqueous +40 G F C B B B B B B B B B B B B B Cyanide, aqueous +80 G D C B B B B B C B C D B D B B Cyclohexane Cyclohexanol +20 C B D G D B B C B D B D B D C B +20 G B D D D B G C B D B D B D G B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 190

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12. Chemical resistance MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Cyclohexanone +20 G G D D D B G G D D D D B D G G Cyclohexylamine +20 G G D D D C D G D D D D B D G D Decahydronaphthalene (decalin) Decahydronaphthalene (decalin) +20 C G D D D C C G D D D D B D G C +60 C G D D D C C G D D D D B D G C Desmodur T +20 D C D D D C G G D D D D B D G F Desmophen 2000 +80 F G F F F F F F B F B F B B F F Detergents, synthetic +60 D F C B B B B F B B B B B B F B Dextrin, aqueous +60 G D B B B B B B B B B B B B B B Dextrose, aqueous +80 G G B B B B B B B B B D B B B B Diacetone alcohol +20 G F C B B B G F C B C B B B F F Dibenzyl ether +20 G G D C C B D G D C D D B D G F Dibutyl ether +20 G G D C C B D G D C D D B D G F Dibuthyl phthalate +20 G B D F F B B B D F D D B D B B Dibuthylphtalat +60 G F D F F B C B D F D D B D B B Dibuthyl sebacate +60 G F D D D C G C D D D D B D C C Dichlorobenzene +20 G G D D D B B C D D D D B D G B Dichlorobutylene +20 G G D D D B C G D D D D B D G B Dichloroacetic acid +60 G D D B B C D G D B D D B D G F B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 191 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Dichloroethane +20 D D D G D C C F D D D D B D D C Dichloroethylene +20 G G D G G C C G D G D D B D G C Dichloromethane +20 D D D D D B B G D D D D B D D B Diesel fuel +60 C C C D D B B B B D B D B D C B Diethylamine +20 G G D B B C D G C B C D B D G D Diethylene glycol +20 G G B B B B B B B B B B B B B B Diethyl ether +20 G G D D D B D G D D D D B D G B Diethylsebacate +20 G G D C C C C G D C D D B D G C Diglycolic acid, aqueous +60 G G C B B B B F C B C B B B F B Dihexyl phthalate +60 G G D D G C D G D G D D B D G C Diisobutylketone +60 G G D F B C D G D B D C B D G F Dimethylamine +20 G G D B B C D G D B D D B D G D Dimethyl ether +20 G G D B B C D G D B D C B D G F Dimethylformamide +60 F D D C C C D F D C D C B D D F Dinonyl phthalate +30 G G D D G C D G D G D D B D G G Dioctyl phthalate +60 D G D D G B C G D G D D B D G B Dioctyl sebacate +60 G G D G G C D G D G D D B D G C Dioxane +60 G G D C C F D G D C D C B C G F B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 192

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12. Chemical resistance MEDIUM Dipents Diphenyl °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X +20 F F D D D B B F C D C D B D F B +20 G F D D D B B G D D D D B D G B Diphenyl oxide +100 G G G G G F G G G G G G B G G F Engine oils +100 B C C D D B B B B D B D B D C B Epichlorohydrin +20 G G G G C F D G G G G G B G G D Essential oils +20 G G D D D B C G D D D D B D G B Ethan +20 B B C D D B B B B D B D B D C B Ethanol (spirit) +20 G C C B B B H B C B C B B B C B Ethanol (spirit) +80 G D D B B B H F D B D B B B F B Ethanol (spirit) with acetic acid (fermentation mixture) (ethanol (spirit) with acetic acid fermentation mixture) +60 G G D B B B H G D B D B B B G B +20 G G C B B B H G D B D B B B G B Ethyl acetate +60 G D D D D C D G D D D D B D G D Ethyl acrylate +20 D G G G F C D D D C D G B G D D Ethylbenzene +20 D F D D D B C C D D D D B D D C Ethyl chloride +20 D C C F C B C G C C C C B C D C Ethylene chloride +20 D C C F C B C G C C C C B C D C B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 193 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Ethylenediamine +60 D D D F B C D G D B D C B C D D Ethylene glycol +100 G D C F B B B F B B B D B B C B Ethylene trichloride +20 G G G G G C F G G G G G B G G F Ethyl ether +20 D D D D C B D D D C D C B D D C Exhaust gases containing hydrogen fluoride, traces Exhaust gases containing carbon dioxide Exhaust gases containing carbon oxide +60 F G B B B B B F B B B B B B F B +60 B F B B B B B B B B B B B B B B +60 B B B B B B B B B B B B B B B B Exhaust gases, nitrous, traces +60 D G B B B B B C F C F D B F D B Exhaust gases, nitrous, traces +80 D G B B B B B C F C F D B F D B Exhaust gases containing hydrochloric acid Exhaust gases containing sulphur dioxide Exhaust gases containing sulphuric acid Exhaust gases containing sulphur +60 G G B B B B B F C B C B B B F B +60 G G B B B B B F C B C C B C F B +60 G G C B B B B F C B C C B C F B +80 G G C B B B B F D B D C B C F B FAM test fuels DIN 51604-A +20 G B D D D B B B C D C D B D D B FAM test fuels DIN 51604-C +20 D D D D D B H C D D D D B D D B Fatty alcohol +20 B G B C C B B F B C B C B C B B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 194

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12. Chemical resistance MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Fats, mineral, animal or vegetable +80 B B C C D B B B B D B D B D B B I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H Fatty acids +100 G G C C G B B G C G C G B G G B Fertilizer salt, aqueous +60 G G C B B B B B B B B B B B B B Fish oil +20 B F B C C B B B B C B C B C B B Fluorine, dry +60 G G G G G F G G D G D D B G G G Fluorobenzene +20 D G D D D B C D D D D D B D D B Fluorocarbon oils +100 F F F F F F F F F F F F B F B F Fluorosilicic acid +100 G G F F F F F F F F F D B F F F Formaldehyde, aqueous +60 D G C B B C G F C B C B B B F F Formamide +60 G G D B B B C G D B D B B F G F Formic acid, aqueous +60 G D D C C B G G D C D C B C G G Fruit juices +100 G D C B B B B F C B C D B B B B Furan Furfurol +20 G D G G G C D G G G G G B G G F +20 G D G G G C G G D G D G B G G F Furfuryl alcohol +20 G D G G G C G G G G G G B G G F Gasohol +20 D D D D D B H C D D D D B D D B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 195 X E D N I

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Materials and Process Engineering MEDIUM Gas oil Gas water Gasoline Gasoline-benzene-ethanol, 50/30/20% Gasoline-benzene mixture, 50/50% Gasoline-benzene mixture, 60/40% Gasoline-benzene mixture, 70/30% Gasoline-benzene mixture, 80/20% °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X +80 B B C D D B B B B D B D B D C B +40 D G D D D B B D B D B D B D D B +60 D D C D D B B B C D C D B D D B +20 D D D D D B H C D D D D B D D B +20 D C D D D B B C D D D D B D D B +20 D C D D D B B C D D D D B D D B +20 D B D D D B B B D D D D B D D B +20 D B D D D B B B D D D D B D D B Gelatine, aqueous +40 C G C B B B B B B B B B B B B B Glacial acetic acid +60 G D D C C C D G D C D D B D G G Glauber's salt, aqueous +20 C G C B B B B F B B B B B B F B Glucose, aqueous +80 G G C B B B B B B B B C B B B B Glue +20 B B B B B B B B B B B B B B B B Glycocoll, aqueous, 10% +40 F G B C B B B F C B C C B C F B Glycol, aqueous +100 G D C B B B C F B B B C B B C B Glycolic acid, aqueous, 37% +20 G G C B B B B B B B B B B B B B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 196

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12. Chemical resistance MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Glycerine, aqueous +100 G G C B B B B B B B B C B B B B Glycerol chlorohydrin +60 G G D C C C G G D C D C B C G F Heating oil (petroleum-based) +60 B B C D D B B B B D B D B D C B Henkel P-3 solution +100 G G C B B B G F B B B C B B F F Heptane +60 B B C D D B B B B D B D B D D B Hexachlorobutadiene +20 G G G G G B B G D G D D B D G B Hexachlorocyclohexane +20 G C G G G B B F G G G D B D G B Hexaldehyde +20 G G D G G C G G D G D D B D G F Hexane Hexanetriol Hexene +60 B B C D D B B B B D B D B D D B +20 G G C B B B B B B B B F B F B B +20 B B C C D B B B C D C D B D F B Hydraulic fluids, hydraulic oils DIN 51524 Hydraulic fluids, phosphoric acid esters HFD Hydraulic fluids, polyglycol-water HFC Hydraulic fluids, Oil-in-water emulsions HFA Hydraulic fluids, water-oil emulsions HFB +80 B B C D D B B B B D B D B D C B +80 D D D D H B H D D H D D B D D B +60 G G C B B B B B B B B B B B B G +55 G G C D D B H F B D B D B D F G +60 G G C D D B H F H D H D B D F G B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 197 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Hydrazine hydrate +20 G C C B B C G C C B C D B C G F Hydrobromic acid, aqueous +60 G D C B B F G G C B C F B F G G Hydrochloric acid, conc. +20 G G D B B B B G D B D C B C G B Hydrochloric acid, conc. +80 G G D B B B C G D B D D B D G B Hydrochloric acid, diluted +20 G D C B B B B G C B B B B B G B Hydrofluoric acid, conc. +20 G G G C C C G G G C G G B C G F Hydrofluosilicic acid, aqueous +60 G G C B B B B G B B B B B B G B Hydrogen +20 B G B B B B B B B B B B B B B B Hydrogen chloride gas +60 G G D B B B B G D B D C B C G B Hydrogen phosphide +20 G G C B B C C F D B D B B F F C Hydrogen peroxide, aqueous +20 G G D B B B B C D B D D B D C B Hydrogen sulphide, dry +60 G F C B B B B F C B C C B C F B Hydrogen sulphide, aqueous +60 G G C B B B B G C B C C B B G B Hydroquinone, aqueous +20 C G C B B B B F B B B C B C F B Hydrosulfite, aqueous +40 G G C B B C G F C B C B B B F F Hydroxylamine sulfate, aqueous +35 G G C B B C G B B B B B B B B F B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 198

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12. Chemical resistance MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Illuminating gas, petrol-free +20 B B C D D B B B B D B D B D B B Ink Iodoform +20 B B B B B B C B C B B B B B B B +20 G G G G B B B G G B G G B G G B Iron(III) chloride, aqueous +40 G F B B B B B F B B B B B B F B Isobutyl alcohol +20 D D B B B B B C C B C B B B B B Isooctane Isophorone Isopropanol +20 B C C D D B B B B D B D B D C B +20 F C F F B C F F F B F F B F F F +60 D G C B B B H B C B C B B B B B Isopropyl acetate +80 D G D C C C D D D C D D B D D D Isopropyl ether +60 D D D G G B D D D G D G B D D B Isopropyl chloride +20 D D D D D B B C D D D D B D D B Kerosene Kerosene +20 B B D D D B B B C D B D B D C B +60 F F B D D B B F B D B D B D F B Kerosene emulsions +40 B B B D D B B B B D B D B D B B Kerosene oil Lactam +60 B B B D D B B B B D B D B D B B +80 G G D D D C D G D D D D B D G F Lactic acid, aqueous 10% +40 G B B B B B B F B B B B B B F B Lanolin (wool grease) +60 B B C C D B B B B D B C B C B B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 199 X E D N I

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Materials and Process Engineering MEDIUM Lauryl alcohol Lavender oil °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X +20 F F B C C B B F B C B C B C F B +20 C F D G G B B C C G C G B G G B Lead acetate, aqueous +60 G D C B B B B F C B B B B B F B Lead acetate, aqueous +100 G D C B B B D F C B B D B B F F Lead nitrate, aqueous +20 F D C B B B B F B B B B B B F B Lemon juice, undiluted +20 G F C F F B H F B F B B B B B B Linseed oil Linoleic acid Liqueurs +60 F C B C C B B F B C B C B C B B +20 G F G G G B C F C G C G B G C B +20 B B B B B B B B B B B B B B B B Lithium bromide, aqueous +20 G B C B B B B B B B B B B B B B Lithium chloride, aqueous +20 G B C B B B B B B B B B B B B B Machine oils, mineral +80 B B C D D B B B B D B D B D C B Magnesium chloride, aqueous Magnesium sulphate, aqueous +100 D G C B B B B F B B B G B B F B +100 D G C B B B B F B B B G B B F B Maize germ oil +60 F F C G D B B F B D B D B D F B Maleic acid, aqueous +100 G G C B B B B F B B B D B D F B Maleic anhydride +60 G G G G G B B F G G G G B G G B Margarine +80 B B C D D B B B B D B D B D B B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 200

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12. Chemical resistance MEDIUM Menthol Mercury °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X +60 G G D D D B C G D D D D B D G B +60 B B B B B B B B B B B B B B B B Mercury salts, aqueous +60 G G C B B B B B B B B B B B B B Mesityl oxide +20 G F G G C F F F F C F G B G G F Methane Methanol +20 B F B C C B B B B C B C B C B B +60 G G C B B B H B C B C B B B C B Methoxybutanol +60 G F C C C B B F B C B D B D F B Methyl acrylate +20 D D D D D C D D D D D D B D D G Methylamine, aqueous +20 G G G B B C D G D B D C B C G D Methyl bromide +20 D D D D D B B F D D D D B D D B Methylene chloride +20 D D D D D B B G D D D D B D D B Methyl ethyl ketone +20 D D D C C B D D D C D D B D D F Methyl isobutyl ketone +20 D D D D C C D D D C D D B D D F Methyl methacrylate +20 D D D D D C D D D D D D B D D F Methyl-tert-Butylether +20 D D D D D B D D D D D D B D D D Milk Milk of lime Mine gas +20 G B B C C B B B B C B C B C B B +80 G G C F F B B G D F D D B C G B +20 B F B C C B B B B C B C B C B B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 201 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Mineral oil +100 B C D D D B B B B D B D B D C B Mineral water +60 G F C B B B B B B B B B B B B B Molasses +100 G G C C C B B F B C B D B D F B Monobromobenzene +20 D D D D D B C D D D D D B D D F Monochloroacetic acid ethyl ester Monochloroacetic acid methyl ester +60 D D D C C B C D D C D D B D D B +60 D D D D B B C D D B D D B D D B Morpholine +60 G G D C C F G F D C D D B D F F Myristyl alcohol +20 B F B B B B B F B B B B B B F B n-propanol Naftolen ZD Naphtha Naphthalene Naphtoic acid Natural gas +60 G D C B B B C B C B C B B B B B +20 F G D D D B B F C D C D B D G B +20 C D D G G B B C D G D G B G G B +60 G G D D D B B G D D D D B D G B +20 G G F G G B B B C G C G B G G B +20 B B B C C B B B B C B C B C B B Nickel acetate, aqueous +20 G D C B B C F F B B B B B B F F Nickel chloride, aqueous +20 G G C B B B B F B B B B B B F B Nickel sulphate, aqueous +60 G G C B B B B F B B B B B B F B Nitric acid, conc. +80 G D D B D F D G D D D D B D G F B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 202

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12. Chemical resistance MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Nitric acid, fuming +60 G D D D D F D G D D D D B D G F Nitric acid, diluted +80 G G C B C B C G C C C D B C C B I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H Nitrobenzene +60 D D D D D C D D D D D D B D D F Nitrogen +20 B B B B B B B B B B B B B B B B Nitrogen tetraoxide +20 G G G G D F G G G D G G B G D F Nitroglycol, aqueous +20 G F C B B B B F D B D F B F F B Nitroglycerine +20 G G G B B B B G D B D C B C G B Nitromethane +20 D D G C C C D D D C D C B C D F Nitropropane Nitrous gases Nitrous oxide +20 D D D C C F D D D C D C B C D F +20 D D D B B B B D D B D D B D D B +20 B B B B B B B B B B B B B B B B o-nitrotoluene +60 D G D D D F D D D D D D B D D F Octylcresol Octane Octyl alcohol Oleum, 10% Oleyl alcohol Olive oil +20 D G D D D C C D G D G D B D D C +20 G F G G G B B C F G F G B G G B +20 G G B B B B B C C B C C B C C B +20 D D D C C B B D D C D D B D D B +20 B D B B B B B B B B B B B B B B +60 B F B C C B B B B C B C B C B B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 203 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Oleic acid +60 B G C D D B B C B D B D B D C B Oxalic acid, aqueous +100 G G D B B B B G D B D D B C G B Ozone +20 C F C B B B B B C C D D B D B B Palmitic acid +60 F F C D D B B F C D C D B D F B Palm kernel fatty acid +60 F F B D D B B F B D B D B D F B Photo emulsions +20 G G B B B B B F B B B B B B F B Photo developer +40 G G C B B B B F C B C B B B F B Photo fixing baths +40 G G C B B B B F C B C B B B F B Pectin +20 B B B B B B B B B B B B B B B B Pentachlorodiphenyl +60 G G D D D F G G D D D D B D G F Pentane +20 F F C D D B B F B D B D B D F B Perchloroethylene +60 G G D D D B B G D D D D B D D B Perchloric acid +100 G G D B B B B G D B D D B D G B Peracetic acid, < 1% +40 D D D D B B B D D D D D B D D B Peracetic acid, < 10% +40 D D D D C B H D D D D D B D D B Petroleum ether +60 B B C D D B B B C D B D B D C B Petroleum +60 B B C D D B B B B D B D B D C B Phenol, aqueous, up to 90% +80 G G D D D B C G D D D D B D G B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 204

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12. Chemical resistance MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Phenyl ethyl ether +20 D D D D D C D D D D D D B D D F Phenylbenzene +20 G G D D D B C G D D D D B D G B I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H Phenylhydrazine +60 G G D D D B C G C D C D B D G C Phenylhydrazine chlorohydrate, aqueous +80 G G D C B C C G C B C D B D G C Phosgene +20 G G G F F F F G G G G G B G G F Phosphorus oxychloride +20 G G G F F F F G D G D G B F G F Phosphoric acid, aqueous +60 G G C B B B B G D B D C B B G B Phosphorus trichloride +20 G G D B B C C G D B D B B F G C Phthalic acid, aqueous +60 G G C B B B B F B B B D B F F B Picric acid +20 G C B C C B B C C C C C B C G B Picric acid, aqueous +20 G G C B B B B B B B B B B B B B Pimple solution (leather pimple) +20 G G F C C C C G F C F G B G G C Pine needle oil +60 B B D D D B B B C D C D B D C B Pinene Piperidine Potash +20 G C C C G B B C C G C G B G G B +20 G G G G G F G G G G G G B G G F +40 G G C B B B B B B B B B B B B B Potassium acetate, aqueous +20 G C C B B B B F C B B B B B F B Potassium bisulfate, aqueous +40 G D C B B B B F B B B B B B F B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 205 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Potassium borate, aqueous +60 G D C B B B B F B B B B B B F B Potassium bromate, 10% +60 G D C B B B B F B B B B B B F B Potassium bromide, aqueous +60 G D C B B B B F B B B B B B F B Potassium carbonate, aqueous +40 G G C B B B B B B B B B B B B B Potassium chlorate, aqueous +60 G D C B B B B F D B D C B C F B Potassium chloride, aqueous +60 G D C B B B B F B B B B B B F B Potassium chromate, aqueous Potassium dichromate, aqueous 40% +20 G D C B B B B F C B C B B B F B +20 G G C B B B B F C B C D B C F B Potassium iodide, aqueous +60 G D C B B B B F B B B C B B F B Potassium nitrate, aqueous +60 G D C B B B B F B B B B B B F B Potassium perchlorate, aqueous Potassium permanganate, aqueous Potassium persulfate, aqueous Potassium sulphate, aqueous +80 G G C B B B B F D B D D B D F B +40 G G C B B B B G D B D D B C G B +60 G G D B B B B G D B D D B C G B +60 G G C B B B B F B B B B B B F B Propane, liquid/gaseous +20 B B B G G B B B B G B D B D B B Propargyl alcohol, aqueous +60 F G B B B B B F B B B C B F F B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 206

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12. Chemical resistance MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Propionic acid, aqueous +60 G G C F F B B G B F B G B F G B Propylene glycol +60 G G C B B B B F B B B B B B F B I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H Propylene oxide +20 G G G G G C G G D G D G B G G G Prussic acid +20 G G C B F B F F F B F F B F B B Pyridine Pyrrole +20 D D D G G F D D D G D D B D D F +20 G G G G D F F C G D G D B D C F Rapeseed oil +20 C C C C C B B B C C C G B G G B Refrigerant according to DIN 8962 R 134a Refrigerant according to DIN 8962 R 134a +20 G C B B B G D F D B D B B B G G +20 G G B G B D D F C G C G B G G G Roasting gases, dry +60 G G C B B B B B D B D B B B B B Sagrotan Salicylic acid Salt water Seawater +20 G D C B B B B B C B C B B B B B +20 G B B B B B B G B B B B B B G B +20 G G B B B B B B B B B B B B G B +20 G C C B B B B B B B B B B B B B Silicic acid, aqueous +60 G G C B B B B G B B B B B B G B Silicone grease +20 B B B B B B B B B B B C B B D B Silicone oil +20 B B B B B B B B B B B C B B D B Silver nitrate, aqueous +100 G G C B B B B F C B C G B C F B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 207 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Silver salts, aqueous +60 G G C B B B B B C B C C B C B B Skydrol +20 D D D G C C D D D F D D B D D D Soap solution, aqueous +20 G B C B B B B F B B B B B B F B Soda, aqueous +60 G G C B B B B B B B B B B B B B Sodium benzoate, aqueous +40 G F C B B B B F B B B B B B F B Sodium bicarbonate +60 G G C B B B B F B B B B B B F B Sodium bicarbonate, aqueous +60 G G C B B B B F B B B B B B F B Sodium bisulfite, aqueous +100 G G C B B B B F B B B B B B F B Sodium chlorate +20 G G D B B B B F D B D D B D F B Sodium chloride +100 G G C B B B B F B B B G B B F B Sodium hypochlorite, aqueous +20 G G C B B B B F C B C D B D F B Sodium nitrate, aqueous +60 G G C B B B B F B B B B B B F B Sodium nitrite +60 G G C B B B B F C B C B B B F B Sodium phosphate, aqueous +60 G G C B B B B F B B B B B B F B Sodium silicate, aqueous +60 G G C B B B B F B B B B B B F B Sodium sulphate, aqueous +60 G G C B B B B F B B B B B B F B Sodium sulfide Sodium sulfide +40 G G C B B B B F B B B B B B F B +100 G G C B B B B F C C C D B C F B Sodium thiosulfate +60 F G B B B B B F D B D B B B F B Spermaceti +20 F F C D D B B F B D B D B G F B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 208

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12. Chemical resistance MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Spruce needle oil +20 G F D G G B B F C D C D B D G B Spindle oil +60 B B C D D B B B B D B D B D B B I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H Starch, aqueous +60 G G B B B B B B B B B B B B B B Starch syrup Stearic acid Steam +60 G G B B B B B F B B B B B B F B +60 B B C B B B B B B B B D B B B B +130 G D D C B D H D D B D D B D D B Stoddard graduate +20 B B D D G B B B B G B G B G G B Styrene +20 G G D D D F C G D D D D B D D F Succinic acid, aqueous +60 G D C B B B B F B B B B B B F B Sugar syrup Sulphur +60 G G G B B B B F B B B B B F F B +60 G F G B B B B F G B G G B G F B Sulphur chloride +20 G G D C G B B B D G D G B G G B Sulphur dioxide, liquid +60 G G D B B B B G D B D D B G G B Sulphur dioxide, dry +80 G G D B B B B F D B D D B C F B Sulphur dioxide, aqueous +60 G G D B B B B G D B D D B C G B Sulphur hexafluoride +20 F F B B B B B B B B B F B B B B Sulphuric acid, conc. +50 G D D B B B C G D B D D B C D B Sulphuric acid, diluted +20 G G D B B B B G C B C C B C G B Sulfuryl chloride +20 G G D B C B B G D C D C B C G B Tallow +60 F G C D D B B F B D B D B D F B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 209 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Tannic acid +60 C G C B B B B B B B B B B B B B Tanning extracts +20 C G C B B B B B B B B B B B B B Tannin Tar Tar oil +40 G B B B B B B F C B C B B B F B +20 G G D D D B F G D D D D B D G B +20 G G D D D B F G D D D D B D G B Tartaric acid, aqueous +60 G G C B B B B B B B B B B B B B Tetrachloroethane +60 G G D D D B C G D D D D B D G B Tetrachloroethylene +60 G G D D D B C G D D D D B D G B Tetraethyl lead +20 G G D D G B B C C G C G B G G B Tetrahydrofuran +20 G G D D D C D G D D D D B D G F Tetrahydronaphthalene (Tetralin) +20 G G D D D B B F D D D D B D G B Thionyl chloride +20 G G D B B B B G D B D C B C G B Thiophene +60 G G D D D F D G D D D D B D G F Tin(II) chloride, aqueous +80 G G C B B B B F B B B B B B F B Tincture of iodine +20 G D C B B B B C B B B B B B C B Titanium tetrachloride +20 C B C B B B C C B B B B B B C B Toluene +20 D D D D D B C D D D D D B D D B Transformer oil +60 B B D D D B B B C D B D B D C B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 210

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12. Chemical resistance MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Transmission fluid type A +20 B B C C G B B B B G B G B G C B Triacetin +20 G G C C B F G G C B C C B D G F Triethanolamine +20 G G C C C C G G D C D D B F G G Triethylaluminum +20 G G G G G C C G G G G G B G G C Triethylborane +20 G G G G G B B G G G G G B G G B Tri-n-butyl phosphate +60 D D D D F B D D D D D D B D D F Tributoxyethyl phosphate +20 G G D D D B C G D D D D B D G F Trichloroacetic acid, aqueous +60 G G D C C B D G C C C C B C G F Trichloroethylene +20 G D D D D B C G D D D D B D D F Trichloroethyl phosphate +20 G G D G G C D G D G D G B G G F Triglycol +20 G F B B B B B F B B B B B B F B Tricresyl phosphate +60 G C D D C F C F D C D D B D G F Trimethylolpropane, aqueous +100 G G C C C B B F D C D C B F F B Trisodium phosphate +20 G F C B B B B B B B B B B B B B Trinitrotoluene +20 G G C C G B C C G G G G B G G B Trioctyl phosphate +60 G G D C C B C F D C D D B G G B Turpentine +60 F D D D D B B G C D C D B D G B Turpentine oil +20 F G D D D B B G C D C D B D G B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 211 X E D N I

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Materials and Process Engineering MEDIUM °C 1) M C A U A R C M S C M D P E M K F F M K F Q M V F R B N H R B N R N E F T P R B S R I I Q M V P X Urea, aqueous +60 G G C B B B B F B B B B B B F B Vaseline Vaseline oil +60 B F B C D B B B B D B D B D C B +60 B F B C D B B B B D B D B D C B Vinyl acetate +20 G G G G G C G G G G G G B G G G Vinyl chloride, liquid +20 G G G G G C G G G G G G B G G G Wax alcohol +60 F F C D D B B F C D B D B G F B Water Water vapor White spirit White oil Whisky Wine +100 D D C B B C C F B B B C B B C B +130 G D D C B D H D D B D D B D D B +60 B F C D D B B F C D B D B D F B +20 B F C C G B B B B G B G B G B B +20 G B B B B B B B B B B B B B B B +20 F B B B B B B B B B B B B B B B Wool grease +50 B B B B B B B B B B B C B B B B Xylamon Xylene +20 D C D D D B C G D D D D B D G B +20 D D D D D B C D D D D D B D D B Yeast, aqueous +20 G F B B B B B B B B B B B B B B Zeolite Zinc acetate +20 B B B B B B B B B B B B B B B B +20 B B C C B B B B C B C B B D B B B = Low or no attack C = Weak to moderate attack D = Severe attack to complete destruction F = No data available, probably suitable, check before use. G = No data available, probably not suitable. H = Special mixture structure required. 1) Test temperature in °C The above information is based on the experience of decades of research in the development and manufacture of seals at the Freudenberg Group. Nevertheless, chemical resistance is only one aspect of the overall operating conditions and there is a possibility that the properties of seals may be noticeably restricted due to unknown factors during practical use. This informa- tion can therefore only represent general, non-binding guide values. We therefore recommend discussing specific applications with our consulting service and always testing them in advance. You can find the latest information on resistance online in our Chemical Resistance Guide. 212

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13. Summary of the standards mentioned 13. SUMMARY OF THE STANDARDS MENTIONED I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A NORM DIN 3601 DIN 3760 DIN 3761 DIN 7168 DIN 7715 DIN 7716 DIN 9088 DIN 16901 DIN 24320 DIN 51524 DIN 51604 DIN 53504 DIN 53508 O-rings - Fluid technology R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H Radial shaft seals Radial shaft seals for motor vehicles General tolerances (free size tolerances) Rubber parts – permissible dimensional tolerances Products made of rubber; Guidelines for storage, maintenance and cleaning Aerospace guidelines for the permissible storage times of products made of elastomers Plastic molded parts; tolerances and acceptance conditions for length dimensions Pressure fluids of the HFAE and HFAS category, properties and requirements Pressure fluids – Hydraulic oils – HL, HLP, HVLP FAM test fuel for polymer materials; composition and requirements Testing of elastomers – tensile test Testing of elastomers – Artificial ageing of soft rubber R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 213 X E D N I

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Materials and Process Engineering NORM DIN 53512 DIN 53513 DIN 53533 DIN 53538 DIN 53545 DIN ISO 34-1 DIN ISO 48 DIN ISO 812 DIN ISO 815 Testing of elastomers; determination of rebound resilience Testing of rubber and elastomers; determination of the viscoelastic properties of rubber under forced off-resonance vibrations Testing of elastomers; testing of heat generation and crushing resistance in the fatigue test Testing of elastomers; standard reference elastomers Determination of the behavior of mineral oil products compared to nitrile rubber vulcanizates Testing of elastomers; determination of behavior at low temperatures (low-temperature behavior); terms, symbols and test methods Testing of elastomers; tear propagation test with the strip specimen Elastomers and thermoplastic elastomers; determination of hardness Testing of elastomers; determination of the cold brittleness temperature under impact stress Testing of elastomers; determination of compression set at ambient, elevated or low temperatures DIN ISO 1431-1 Determination of resistance to cracking under the influence of ozone Testing of caoutchouc and rubber; DIN ISO 1629 Rubber and Latices; Classification Abbreviations DIN ISO 1817 DIN ISO 4649 214 Testing of rubber and caoutchouc; Determination of the effect of liquids Testing of rubber and elastomers; wear test; determination of abrasion

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13. Summary of the standards mentioned Testing of rubber and caoutchouc; hardness testing according to Shore A and D I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H Testing of plastics and elastomers; determination of density NORM DIN ISO 7619-1 DIN EN ISO 1183 DIN EN ISO 6721 Testing of polymer materials; torsional vibration test VDMA 24317 ASTM D 395 ASTM D 471 ASTM D 746 Fluid technology; flame-retardant hydraulic fluids; minimum technical requirements Testing of rubber; determination of compression set Testing of rubber; determination of the behavior against liquids Determination of the embrittlement temperature of plastics and elastomers under impact stress ASTM D 945 Determination of the behavior under compressive deformation or shear stress (mechanical vibration meter) Testing of rubber; ASTM D 1418 ASTM D 1600 Rubber and rubber-latex; classification and designations Standard terminology for abbreviated terms in connection with plastics ASTM D 2000 Classification of rubber products for the automotive industry R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 215 X E D N I

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Materials and Process Engineering 14. EXCURSUS: COMMON TERMINOLOGY IN THE RUBBER INDUSTRY Agglomerates Agglomerates are powdery substances that have been combined into a solid compound using technical processes. This connection is based on purely phys- ical forces and can be easily dissolved again depending on the process used. Agglomeration is preferably used to avoid dust emissions or to make powder materials easier to handle. In everyday life, agglomerates are used in instant coffee, for example. Aggregate state Aggregate states are the phases that matter can assume. These are solid, liquid or gaseous. A fourth aggregate state de- scribed by physics is plasma – an ionized gas. The transitions are shown in → Fig. 89. Amorphous This term describes the arrangement of atoms in a body. In contrast to crystals, amorphous materials do not have an or- dered structure. Elastomers belong to the amorphous materials, as their polymer chains are disordered in the matrix. Aromatics Aromatics are special ring-shaped struc- tures that are unsaturated, i.e. have double bonds. These double bonds are conjugat- ed, i.e. there is a single bond between each double bond. This gives aromatics their typical chemical properties. Aromatics exist as mono- and poly-rings. Brownian molecular motion This type of movement of molecules is named after the Scottish botanist Robert Brown, who observed the jerky and random movement of tiny particles in liquids in 1827. Molecules always have their own motion as soon as their temperature is above the absolute zero point of 0 Kelvin (–273.15 °C). This movement increases the warmer an object is and ultimately represents the definition of temperature. Brownian motion is based on collisions that molecules can exert due to their own motion. The higher the temperature, the more pronounced the Brownian motion, as more energy can be transferred by the molecules. i o n < R e c o m b i n a t i o n > I o n i z a t < Vaporize Condensing > y i n g o li d i f M e l t i n g > < S PLASMA LIQUIDITY GAS > n o i t a m i l b u S n o i t a m i l b u s e R < FIXED BODY Fig. 89 Overview of the aggregate states and their transitions 216

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14. Excursus: Common terminology in the rubber industry Dispersing Dispersing is the homogeneous mixing of at least two substances that are soluble in each other. The term "emulsion paint" is commonly used in everyday life. The pigments in these paints are so evenly distributed that they give the impression of a homo- geneous mixture. The degree of dispersion therefore describes how well the compo- nents are distributed in the mixture. Entropy elasticity This term is a combination of a physical quantity and a physical property of a ma- terial. These are briefly explained below before the entropy elasticity is discussed in more detail. Entropy In simple terms, entropy is the disorder of a system. Disordered states have a much lower energy level than ordered states. In nature, everything automatically strives towards the lowest possible energy level. Any deviation from this principle is associated with the supply of energy. If you mix apple juice in water, for ex- ample, you can see streaks of pure fruit juice for a short time. These streaks represent a higher order, as the water and juice are arranged next to each other. Without external influence, the juice will now be evenly distributed in the water, which repre- sents a more disordered state as the juice and water are mixed together – a state of the lowest energy level. Elasticity Elasticity describes the ability of a ma- terial to return to its original shape af- ter deformation. For example, a spring will return to its original shape after moderate deformation. Elastomers consist of long, partly branched molec- ular chains. Due to their structure, the individual links can rotate against each other. This rotatability is disordered, which leads to a randomly aligned polymer ball. This means that the molecular chains are intertwined and twisted. A certain entropy or disorder can be as- signed to this state. If the material is now shaped, the molecular chains slide against each other. The entanglements or twists are dissolved – the polymer chains assume an ordered state with a higher energy level. If the force used to deform the material is removed, the ma- terial will return to a more disordered state of entanglement due to entropy elasticity and possible low energy levels. The new outer shape will be the same as the initial shape due to the elastic com- ponent. On a molecular level, however, a new arrangement occurs until the lowest energy level is reached due to the random rotatability of the chain elements. Glass transition temperature As already explained with regard to en- tropy elasticity, elastomers consist of ran- domly interlaced polymer chains, which are created by the possibility of rotational movement of the individual chain links. This flexibility increases the higher the temperature. Externally, an elastomer thus becomes easier to stretch and less rigid. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 217 X E D N I

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Materials and Process Engineering However, the exact opposite happens as the temperature falls and the chain links find it increasingly difficult to move due to the lack of thermal energy. At the glass transition temperature (Tg), the point is reached at which movement is no longer possible. Below this temperature, the ma- terial solidifies and assumes a brittle, glass-like state. This process is reversible. The glass transition temperature is signif- icantly influenced by the degree of cross-linking. Higher cross-linking always leads to a restriction of movement of the polymer chains, which is why the materi- al becomes correspondingly harder → Tg is increased. Hooke's law This law describes a special form of elas- tic behavior. Hooke's law states that the deformation of a material is proportion- al to the force acting on it. This is particu- larly the case with metals when they are subjected to moderate deformation. This is also referred to as energy elasticity. Isotropy In physics, isotropy describes the inde- pendence of a property from the direction of observation. In everyday life, we are familiar with the effect of a light bulb. Its light rays are not directional and can therefore be emitted in all three spatial directions. In the field of elastomers, isotropy de- scribes a directional independence when it comes to physical quantities. Rubber materials generally behave isotropically. For example, the hardness of an elasto- mer is the same in every direction due to its isotropic properties. However, slight anisotropic tendencies can be detected in the tensile strength test, which are caused by the rolling processes. However, the effects on the functionality are very small. Kerosenes Kerosenes are long-chain, saturated al- kanes. In everyday life, kerosenes are known as candle wax, for example. They can be liquid at lower chain lengths and solid at higher chain lengths. Naphthenes Naphthenes are cyclic (ring-shaped) compounds that consist of saturated hydrocarbons. They are therefore alkanes that are present in ring structures. The structures range from simple ring struc- tures (monocycles) to interconnected rings (polycyclic alkanes). These can have two nodes, bridge connections or simple nodes, or occur as so-called spiro com- pounds. Permeability The term "permeability" refers to the gas permeability of a material. It is a charac- teristic value for how well a material allows gases to pass through it or how well it retains them. Basically, all polymer materials are gas-permeable. Although the value can be reduced by various ad- ditives, gas permeability can never be completely prevented. In everyday life, we encounter permeabil- ity in plastic sparkling water bottles. These are filled with a higher gas pressure, as the carbonic acid degrades during longer storage due to the gas permeabil- ity. With glass bottles, which are gener- ally impermeable to gas, these high pres- sures are not necessary as the carbonic acid cannot degrade . 218

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14. Excursus: Common terminology in the rubber industry Plasticizing “Plasticizing” refers to the improvement of flowability. Depending on the sub- stance group, this can be achieved by increasing the temperature. Increasing the temperature usually results in a reduction in viscosity – a measure of flowability. In some cases, a flowability is required that cannot be achieved by increasing the temperature. Plasticizers or similar sub- stances are used here, to achieve the effect of plastification, for example. Radial force and axial force These two terms describe the direction of forces in relation to a shaft. The term "radial force" refers to the force that runs perpendicular to the shaft, whereas the axial force runs parallel to the shaft. You can memorize the difference by im- agining the forces as arrows. If we look at the radius of the shaft, we can measure it from the center to the edge of the shaft. Radial forces also act in exactly this direction. If we measure the length of the shaft or axle, we would measure it along the axis. The axial forces act accordingly in this di- rection. Reversible and irreversible effects An effect is reversible if it can be reversed. In sealing technology, this is particularly attractive in the case of expansions or compressions of seals, as these should counter the deformation in a reversible manner. Radial force Axial force Fig. 90 Radial and axial force In everyday life, we know reversible effects from springs that are pulled apart and then return to their original shape as soon as they are released. The bending of a metal sheet is a permanent deforma- tion and is therefore irreversible. The shattering of glass is also irreversible, as it does not reassemble itself. RGT rule (derived from Arrhenius equation) The reaction rate-temperature rule – also known as Van't Hoff's law – states that the reaction rate doubles or triples with a temperature difference of 10 Kelvin. This rule was derived from the Arrenius equation and represents a simplification. Since the vulcanization reaction does not depend on this rule, it is important to en- sure good process monitoring. Irreversible effects, on the other hand, are external forces or influences that cannot be reversed. However, it is also advisable to take this rule into account in the daily use of seals, as a seal can be exposed to chemical I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 219 X E D N I

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Materials and Process Engineering attacks, which usually occur more quickly at high temperatures. In everyday life, the validity of the RTG rule can be seen, in cooking processes, for example: The higher the temperature, the faster the cooking process. Rubber The term rubber is not specific. On the one hand, it stands for the base polymer, which is not cross-linked and therefore has no elastic properties. On the other hand, it refers to the vulcanized rubber that we are familiar with in everyday life. In the private sector, however, it is main- ly the elastic, cross-linked material that is referred to, as non-cross-linked rubber of- fers no possibility of end use. Saturated and unsaturated compounds Molecules without double bonds are referred to as "saturated compounds." The opposite are unsaturated compounds, which accordingly have double bonds in their structure. In everyday life, we are familiar with this type of compound in oils and fats. On the one hand, there are monounsaturated or even polyunsaturated oils (olive oil). On the other hand, there is the saturated variant (deep-frying fat). While our body can V R M Fig. 91 Diagram of the stick-slip effect 220 carry out reactions on unsaturated com- pounds, this is not the case with saturated molecules. A similar situation exists in the sealing in- dustry when the task is to provide seals that have to withstand oxygen or ozone or other oxidative chemicals. Here, as can be assumed, the less reactive, saturated compounds are more suitable. Stick-slip effect When bodies switch quickly between sticking and sliding during movements, the so-called stick-slip effect comes into play. This rapid change creates an oscilla- tion that is usually accompanied by bright sounds. The mechanism is based on a cy- clical sequence of adhesion, build-up of tension, release of tension and slipping, followed by adhesion again. An equivalent diagram makes this effect clearer. A hand crank can be seen, which is connected to a spring via a threaded spindle. The spring in turn is connected to a mass. If the crank is now turned to move the mass, tension is built up in the spring, while the weight does not move at first. This is due to the fact that the static friction is greater than the tensile stress at this moment. If the tension ex- ceeds the static friction, the mass begins to slide – the tension in the spring is re- leased. The mass comes to a stop because the static friction again exceeds the tension in the spring. This process now repeats itself. In everyday life, the stick-slip effect is known in the form of squealing tires dur- ing braking, the sound produced by string instruments or a glass harp, and creaking doors.

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14. Excursus: Common terminology in the rubber industry Viscoelasticity Viscoelastic behavior is a combination of two mechanical behaviors. The term in- cludes both elastic and viscous or plastic behavior. An elastic material is one which, after a forced deformation, returns to its initial state. A spring, for example, can be compressed or extended to a certain degree without being permanently de- formed. This happens without a time delay. In order to maintain this defor- mation, this force must be applied at all times. A material that yields to a deformation without restriction and retains the de- formed state behaves "plastically" or "vis- cously." It is not able to return to its orig- inal shape. Liquids respond irreversibly to deformation, i.e. they exhibit viscous behavior. In addition, this deformation occurs with a time delay. Viscoelastic behavior is the combination of both properties. It describes a body that strives to return to its original state after deformation, but yields to a certain extent to the deformation. Rubber materials are said to behave viscoelastically, although the elastic com- ponent is predominant. In practice, this means that elastomers deform to a certain extent after a force is applied (elastic component). However, this force decreases with a time delay and the elastomer structure adapts to the deformation (viscous part). How strong- ly or weakly the elastomer yields to this deformation can therefore be seen as the "quality." The simplified model of this behavior is shown in the following diagram. The elas- tic component, indicated by a spring, is shown on the left and the viscous com- ponent, indicated by a damper, is shown on the right. In practice, there are corre- spondingly more complex models with different combinations of these two com- ponents. K Fig. 92 Kelvin body as a model of visco- elastic behavior I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O T A C I I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 221 X E D N I

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Materials and Process Engineering 222

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S E A L S F O R R O T A R Y A P P L I C A T I O N S 2 2 3 INDEX STUFFING BOX PACKINGS DIAPHRAGMS BOOTS & BELLOWS HYDRAULIC ACCUMULATORS SPECIAL SEALING PRODUCTS STATIC SEALS FLUID POWER APPLICATIONS – PNEUMATICS FLUID POWER APPLICATIONS – HYDRAULICS SEALS FOR ROTARY APPLICATIONS MATERIALS AND PROCESS ENGINEERING INTRODUCTION & SERVICES

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Seals for Rotary Applications TABLE OF CONTENTS 1. PRODUCT OVERVIEW 2. PRODUCT GROUPS 2.1 Simmerring® 2.2 2.3 2.4 Radiamatic® shaft seals Simmerring® cassette seals Simmerring® combi seals 3. SEALING MECHANISM USING THE EXAMPLE OF THE SIMMERRING® 3.1 3.2 3.3 3.4 3.5 Influencing parameters Dynamic sealing function Sealing lips with helix (special design) Lubrication and friction Static tightness and fit in the bore 4. MEDIA TO BE SEALED Fluid and material selection Interactions between fluids and elastomer materials 4.1 4.2 4.3 Mineral oils 4.4 4.5 4.6 Greases 4.7 Aggressive media 4.8 Synthetic lubricants Lube & Seal Contaminants in the fluid to be sealed 5. MATERIALS 5.1 Standard materials for Simmerring® 5.2 Special materials for Simmerring® 5.3 Materials for heavy industry 5.4 Materials for the process industry 224 228 258 258 271 277 282 285 285 285 288 289 291 293 293 293 295 296 297 297 298 298 299 302 304 306 308

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6. Boundary conditions Circumferential speeds of the shaft INFLUENCING FACTORS 6.1 6.2 6.3 Temperature 6.4 6.5 ATEX applications 6.6 Pressure 6.7 Sealing against dirt Tightness at low temperatures 7. SPECIAL DESIGNS 7.1 7.2 7.3 7.4 Designs for pressure applications PTFE sealing solutions Further solutions Circumferential Simmerring® 8. DESIGN NOTES 8.1 Shaft design Surface roughness Shaft materials Surface hardness of the counter surface Shaft machining Check the shaft lead Damage to the shaft Coaxiality Runout deviation Installation chamfer on shaft Design of the housing Roughness Tolerance Depth Chamfer Thermal expansion Split housings Stiffness Retaining claw 8.2 9. MODIFIED CATALOG SEALS Table of Contents 309 309 309 311 313 313 313 314 316 316 318 320 321 322 322 323 323 323 324 324 328 328 328 328 331 331 331 331 331 331 331 332 332 333 I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 225 X E D N I

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Seals for Rotary Applications 10. PRESELECTION OF SEALS FOR ROTARY APPLICATIONS 10.1 Preselection Simmerring® 10.2 Preselection of Simmerring® cassette and combi seals 10.3 Product finder 11. HANDLING AND INSTALLATION OF RADIAL SHAFT SEALS 11.1 Goods receipt of components 11.2 Handling 11.3 Greasing of Simmerring® 11.4 Packaging of Simmerring® 11.5 Storage time 11.6 Installation in the housing bore Hammer installation Gluing in Simmerring® Wetting of the adhesive part for installation 11.7 Installation on the shaft 11.8 Installation of special designs Installation MSS1 Installation MSS7 Installation of Simmerring® with sealing lip made of PTFE Installation of Simmerring® cassette seal Installation types Installation of Simmerring® combi seal 11.9 Joining and installing open radial shaft seals on site 11.10 Replacing radial shaft seals 12. FAILURE ANALYSIS 12.1 Leakage definition – the standard, leakage terms, cause, classification Leakage Short term leakage Analysis of leakage causes: static and dynamic leakage Static leakage Dynamic leakage Lubricant Operating conditions and environmental influences Classification of leakage duration: short-term and long-term Presentation of various cases of damage to the Simmerring® Summary 12.2 Incorrect handling and corrective measures 226 338 338 344 346 358 358 358 359 359 360 361 366 367 367 368 369 369 369 371 372 373 376 378 379 381 381 381 381 381 382 382 382 383 384 387 390 391

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13. SIMMERRING® ENGINEERING 13.1 Comprehensive advice from the sealing experts 13.2 Characterization Radial shaft seal (RSS) Characterization of morphology Characterization of chemical composition Characterization of mechanical properties Seal counter surface 13.3 Modeling Functional tests on a test rig Dynamic cycle test rigs High-speed test rigs Pressure test rigs Dust and sludge test rigs Simulation 13.4 Services 14. SPECIAL SEALS 14.1 Micro-Simmerring® 14.2 Sealing caps GA, GSA Table of Contents 402 402 402 402 402 403 404 405 408 408 409 409 409 409 410 410 411 411 413 I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 227 X E D N I

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Seals for Rotary Applications 1. PRODUCT OVERVIEW DESIGN DESCRIPTION MAIN APPLICATIONS PRODUCT GROUP Simmerring® BAUM/ BAUMSL Standard design with rubber- ized outer diameter and friction- optimized sealing profile Industrial gearboxes; axles (when subject to moderate dirt); electro motors; power tools; agricultural and construction machinery gearboxes PSS Special design with rubber- ized outer diameter and friction-optimized, sinusoidal sealing profile Industrial gearboxes; electro motors; power tools; robotics B1/B1SL Standard design with metal outer diameter B2/B2SL Standard design with metal outer diameter BD Partially rubberized outer diameter Industrial gearboxes; axles (when subject to moderate dirt); electro motors; power tools; heavy industry (cranes; planetary gearboxes etc.) Industrial gearboxes; axles (when subject to moderate dirt); power tools; heavy industry (cranes, planetary gearboxes etc.) Industrial gearboxes; axles (when subject to moderate dirt); power tools; agricultural and construction machinery gearboxes BABSL Pressure-resistant type with rubberized outer press fit that can be used without a back-up ring Pressurized units such as hydraulic pumps, motors and hydro dynamic couplings 228

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® 72 NBR 902 ‒40 … +100 75 FKM 585 ‒25 … +160 Yes No Further information on our product portfolio Other materials possible 75 FKM 585 ‒25 … +160 No No 72 NBR 902 ‒40 … +100 Other materials possible 72 NBR 902 ‒40 … +100 Yes No Yes No Other materials possible Application specific selection of the material Material dependent No 72 NBR 902 ‒40 … +100 75 FKM 595 ‒25 … +160 Yes Other materials possible No No I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 229 X E D N I

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Seals for Rotary Applications DESIGN DESCRIPTION MAIN APPLICATIONS Pressure-resistant type with rubberized outer press fit and low-wear sealing lip profile that can be used without a back-up ring Pressure-resistant type with rubberized outer press fit; sealing texture on the air side of the sealing lip; short, very stable sealing lip Hydrostatic drives High-pressure pumps with low speed PPS BAHD HLPS (High Low Pressure Springless lip, integrated back-up ring Heavy-duty hydraulic pumps Seal) BDSLV BA SL X6 BA SL SF BAOF B1OF Designs for special dirt requirements with non- woven dust lip Crankshaft seal Designs for special dirt re- quirements, two dust lips provide additional protection for medium contamination environments Designs for special dirt require- ments, with axial dust lip and slinger to provide additional protection in medium – high contamination environments Gearboxes; axles: pinion seal Gearboxes; axles: pinion seal Standard design with rubberized outer diameter, sealing lip without spring Electric vehicles; electro motors; sealing of pivot bearings and actuators Standard design with metal outer diameter, sealing lip without spring Electric vehicles; electro motors; sealing of pivot bearings and actuators PRODUCT GROUP Simmerring® 230

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® 75 FKM 595 ‒25 … +160 Other materials possible 90 NBR 129208 88 FKM 107725 Other materials possible Application specific selection of the material Application specific selection of the material Application specific selection of the material Application specific selection of the material Yes No ‒30 … +100 ‒25 … +160 Material dependent No Material dependent No Material dependent No Material dependent No 72 NBR 902 ‒40 … +100 72 NBR 902 ‒40 … +100 Yes Yes No No No No No No No No I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 231 X E D N I

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Seals for Rotary Applications DESIGN DESCRIPTION MAIN APPLICATIONS BDRK/ BDLK Unidirectional helix: Left-hand helix LK Right-hand helix RK Improved sealing reliability at high circumferential speeds and temperatures Unidirectional helix: for one direction of shaft rotation Bi-directional helix: for both directions of shaft rotation Engines; gearboxes; axle drives BAE SL X6 Design for separation of water suds and grease lubri- cated bearings Washing machines CTI Two-component pressure resistant seal: PTFE sealing lip on air side; rubber sealing lip on oil side Use in central tire inflation systems (CTIS) for agricultural and construction machinery BA DUO Two sealing lips, for separating two media, narrow solution, can also be used for medium dirt ingress from the outside Separation of two media Two stand- ard designs, e.g. BAUM Two standard designs, e.g. BAUM, installed back-to-back Separation of two media Micro Simmer- ring® Micro Simmerring® for rotary applications with shaft diameters 1–3 mm Use in demanding, customer- specific miniature applications such as micro pumps, micro drives and micro actuators PRODUCT GROUP Simmerring® 232

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® Application specific selection of the material Material dependent No No Application specific selection of the material Application specific selection of the material Application specific selection of the material Application specific selection of the material Material dependent No Material dependent No Material dependent No Material dependent No No No No No EPDM; NBR; FKM; FFKM; 75 Fluoro- prene® XP 41 ‒35 … +200 Material dependent No No I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 233 X E D N I

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Seals for Rotary Applications PRODUCT GROUP PTFE Simmerring® DESIGN DESCRIPTION MAIN APPLICATIONS B2PT B1PT Design with sealing lip made of PTFE clamped in metal housing made of stainless steel (V4A) Chemical engineering; mechanical engineering; mixers; centrifuges; pumps; rotary pressure feedthroughs Combination of metal case and PTFE excluder lip using an innovative bonding process Central tire inflation systems (CTIS); rotary feedthroughs; mechanical engineering BlueSeal Patented friction-optimized lip design with high chemical resistance Food industry; pharmaceutical industry; mechanical engi- neering; motors; retarders PTS Combination of newly devel- oped PTFE sealing lip on oil side and rubber dust lip on air side Use in special fluids for insuffi- cient lubrication and dry run- ning; in two-stroke engines; compressors; in food industry; in chemical industry BAPTSLV Combination of PTFE sealing lip with helix on the oil side and non-woven dust lip on the air side Engines; crankshaft seal BAAT Design with PTFE-coated sealing lip: coating on the air side of the sealing lip Industrial drives 234

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® Application-specific PTFE materials ‒80 … +200 Yes Application-specific PTFE materials Application-specific PTFE materials Application-specific PTFE materials Application specific selection of the material Application specific selection of the material – – – – – No No No No No No No No No No No I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 235 X E D N I

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Seals for Rotary Applications DESIGN DESCRIPTION MAIN APPLICATIONS MSS1 Standard BAUM design, combined with an inner primary seal with sinusoidal sealing lip as one-piece solution. Design for internal dirt contamination protection Industrial gearboxes; drive technology; robotics MSS1 HS MSS3 MSS7 High-speed version of MSS1. Standard BAUM design, combined with an inner primary seal with sinusoidal sealing lip as a one-piece solution. Design for internal dirt contamination protection at high shaft speeds Modified standard BAUM design with bonded special non-woven or a PTFE extruder lip. Design for special dirt requirments Standard BAUM design combined with a rubber coated sleeve with axial dust lips as one-piece solution for special external contamina- tion requirements Industrial gearboxes; drive technology; robotics Drive technology; industrial gearboxes; agricultural and construction machinery Industrial gearboxes; drive technology PRODUCT GROUP Modular sealing systems 236

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H 72 NBR 902/ 75 FKM 585 ‒40 … +100 75 FKM 585/ 75 FKM 585 ‒25 … +160 72 NBR 902/ 75 FKM 585 ‒25 … +100 75 FKM 585/ 75 FKM 585 ‒25 … +160 72 NBR 902 ‒40 … +100 75 FKM 585 ‒25 … +160 Yes No R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P No No No No S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A 72 NBR 902/ 72 NBR 902 ‒40 … +80 Yes No S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 237 X E D N I

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Seals for Rotary Applications DESIGN DESCRIPTION MAIN APPLICATIONS Type 1 Type 2 Type 3 Type 4 Cassette seal with labyrinth structure, special machining of the slip ring surface on which the sealing lip acts. For road use, characterized by low contamination tendency and high speed. Safe installa- tion and handling due to the integrated contact surface Cassette seal with labyrinth structure, special machining of the slip ring surface on which the sealing lip acts. Used for applications with medium contamination and medium speed. Safe installa- tion and handling due to the integrated contact surface Cassette seal with labyrinth structure, special machining of the slip ring surface on which the seal lip acts. Use for ex- treme dirt ingress and for gen- eral applications with contami- nation. Reliable installation and handling due to the integrated contact surface Cassette seal with improved labyrinth structure, special ma- chining of the slip ring surface on which the sealing lip acts. Use in extremely harsh envi- ronments requiring higher dirt protection than Type 3. Relia- ble installation and handling due to the integrated contact surface Wheel hubs and fixed cardan shaft for commercial vehicles Wheel hubs and cardan shafts for commercial vehicles com- bining road and off-road use Wheel hubs and fixed cardan shafts for agricultural and construction machinery; rotary harrows; disc harrows; various units Harrows and fertilizer spread- ers; wheel hubs, cardan shafts for agricultural machinery; wheel hubs, cardan shafts, castors and undercarriages for construction machinery PRODUCT GROUP Cassette seals 238

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H NBR ‒40 … +80 FKM ‒25 … +120 NBR ‒40 … +80 FKM ‒25 … +120 NBR ‒40 … +80 FKM ‒25 … +120 NBR ‒40 … +80 FKM ‒25 … +120 Yes No R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P Yes No Yes No No No S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 239 X E D N I

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Seals for Rotary Applications DESIGN DESCRIPTION MAIN APPLICATIONS HS Bearing unit Soft Unitized PTFE Cassette seal CASCO Casette seal with labyrinth structure, special machining of the slip ring surface on which the sealing lip acts. Used in ap- plications characterized by high speeds and where it is impor- tant to reduce the temperature at the main sealing lip. Reliable installation and handling due to the integrated contact surface Cassette seal in special design, material FKM, slip ring in stain- less steel. Integrated design in roller bearings to protect against contamination Cassette seal in special design with multiple axial dust lip, material FKM or NBR. Design for significant dirt ingress, the slip ring can be assembled separately from the RSS during installation Special cassette seal with PTFE sealing lip with lead, dust lip made of non-woven fabric. Good protection against dust ingress. Safe handling and easy installation Special cassette seal with axial sealing lip and double guide, material FKM, dust lip in FKM or non-woven fabric. Designed for long life, very low friction and very good re- sistance to high eccentricity. Safe handling and easy instal- lation Pinions; differentials; transmissions for agricultural machinery and commercial vehicles Grease lubricated wheel hubs Wheel hubs and pinions in axles for agricultural and construction machinery and commercial vehicles Crankshaft seals in diesel engines Crankshaft seals in diesel engines PRODUCT GROUP Cassette seals 240

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H FKM ‒25 … +120 No No R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P NBR ‒30 … +80 No No NBR ‒40 … +80 FKM ‒25 … +120 No No PTFE ‒20 … +130 No No S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B FKM ‒45 … +150 FKM ‒45 … +150 No No S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 241 X E D N I

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Seals for Rotary Applications DESIGN DESCRIPTION MAIN APPLICATIONS Combi Combi SF5 Combi SF6 Combi SF8 Combi seal with additional dirt deflector made of foamed polyurethane. Requires LOCTITE on the outer diameter for static sealing. Used in applications with low and predominantly dry contami- nation (if the cross-section does not permit the use of a cassette seal) Combi seal with additional dirt deflector made of hard polyurethane. Requires LOCTITE on the outer diameter for static sealing. Used in applications with medium dry and wet contamination, limited axial shaft movement or when the cross-section does not permit the use of a cassette seal Combi seal with additional dirt deflector made of hard polyurethane. Requires LOCTITE on the outer diameter to improve static seal. Use in medium dry and wet conta- mination and with axial reciprocation Combi seal with additional dirt deflector made of hard polyurethane. Integrated static seal on the outer dia meter. Use in medium dry and wet contamination and with axial reciprocation Wheel hubs; cardan shaft and power take-off shaft for agricultural machinery Wheel hubs, cardan shaft with limited axial movement and power take-off shaft for agricultural machines Axles; in particular cardan shafts in driven, steerable axles Axles, in particular cardan shafts in driven, steerable axles PRODUCT GROUP Combi seals 242

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® NBR + AU ‒40 … +80 FKM + AU ‒25 … +120; max. T for AU +100 NBR + AU ‒40 … +80 FKM + AU ‒25 … +120; max. T for AU +100 NBR + AU ‒40 … +80 FKM + AU ‒25 … +120; max. T for AU +100 NBR + AU ‒40 … +80 FKM + AU ‒25 … +120; max. T for AU +100 Yes No Yes No Yes No Yes No I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 243 X E D N I

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Seals for Rotary Applications DESIGN DESCRIPTION MAIN APPLICATIONS Combi SF19 Combi SF21 Combi SF22 Combi seal with additional dirt deflector made of hard polyurethane and external rubber wiper. Integrated static seal on the outer diameter. Use for significant dry and wet contamination and axial reciprocation Combi seal with additional hard polyurethane dirt deflec- tor and outer rubber wiper. Improved polyurethane shape and materials. Use in harsh environments due to improved polyurethane shape and materials, as well as in applications character- ized by axial reciprocation Combi seal with additional hard polyurethane dirt deflec- tor and outer rubber wiper. Improved polyurethane shape and materials. Integrated static seal on outer diameter. Excellent performance in axial reciprocation. Use in harsh environments due to improved polyurethane shape and materials and in applications characterized by significant axial reciprocation Axles; in particular cardan shafts in driven, steerable axles Axles; in particular cardan shafts in driven, steerable axles Axles; in particular cardan shafts in driven, steerable axles PRODUCT GROUP Combi seals 244

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H NBR + AU ‒40 … +80 FKM + AU ‒25 … +120; max. T for AU +100 NBR + AU ‒40 … +80 FKM + AU ‒25 … +120; max. T for AU +100 NBR + AU ‒40 … +80 FKM + AU ‒25 … +120; max. T for AU +100 Yes No R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P No No No No S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 245 X E D N I

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Seals for Rotary Applications DESIGN DESCRIPTION MAIN APPLICATIONS HTS II 9535 Self-retaining PTFE shaft seal – standard version HTS II 9536 Self-retaining PTFE shaft seal – with additional dust lip HTS II 9538 Self-retaining PTFE shaft seal – with additional sealing lip HTS II 9539 Self-retaining PTFE shaft seal – Hygienic Design version Process industry; chemical industry; food industry, e.g. mixers, kneaders, pumps, compressors Process industry; chemical industry; food industry, e.g. mixers, kneaders, pumps, compressors Process industry; chemical industry; food industry, e.g. mixers, kneaders, pumps, compressors Process industry; chemical industry; food industry, e.g. mixers, kneaders, pumps, compressors HTS II 9541 Self-retaining PTFE shaft seal – with helix at the sealing lip for high dynamic recirculation capacity Process industry; chemical industry; food industry, e.g. pumps, compressors HTS II 9564 Self-retaining PTFE shaft seal – Hygienic Design version espe- cially for dry running Process industry; chemical industry; food industry, e.g. mixers, kneaders, pumps, compressors Type 9444 Robust PTFE shaft seal with worm spring on the sealing lip and an O-ring in the static part Process industry; chemical industry; general industry Type 9445 Robust PTFE shaft seal with worm spring on the sealing lip Process industry; chemical industry; general industry PRODUCT GROUP Radiamatic® HTS II PTFE shaft seals 246

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® PTFE ‒80 … +200 Yes PTFE ‒80 … +200 PTFE ‒80 … +200 Yes Yes PTFE ‒80 … +200 Yes PTFE ‒80 … +200 PTFE ‒80 … +200 PTFE ‒20 … +200 PTFE ‒20 … +200 Yes Yes Yes Yes No No No No No No Yes Yes I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 247 X E D N I

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Seals for Rotary Applications DESIGN DESCRIPTION MAIN APPLICATIONS Type 9460 Robust PTFE shaft seal with elastomer support wedge on the static part Process industry; chemical industry; general industry Type 9461 Robust PTFE shaft seal with support function on the static part – wide version Process industry; chemical industry; general industry Type 9960 Robust, pure PTFE shaft seal Process industry; chemical industry; general industry Type 9961 Robust, pure PTFE shaft seal with reinforced static part Process industry; chemical industry; general industry G61 G62 G68 G69 Self-retaining PTFE shaft seal with corrugated sealing lip – standard version Process industry; chemical industry; food industry, e.g. pumps, compressors Self-retaining PTFE shaft seal with corrugated sealing lip – with additional dust lip Process industry; chemical industry; food industry, e.g. pumps, compressors Self-retaining PTFE shaft seal with corrugated sealing lip – with additional sealing lip Process industry; chemical industry; food industry, e.g. pumps, compressors Self-retaining PTFE shaft seal with corrugated sealing lip – Hygienic Design version Process industry; chemical industry; food industry, e.g. pumps, compressors PRODUCT GROUP PTFE shaft seals Gerromatic 248

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® PTFE ‒20 … +200 PTFE ‒20 … +200 PTFE ‒20 … +200 PTFE ‒20 … +200 PTFE ‒80 … +200 PTFE ‒80 … +200 PTFE ‒80 … +200 PTFE ‒80 … +200 Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 249 X E D N I

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Seals for Rotary Applications DESIGN DESCRIPTION MAIN APPLICATIONS RCD Wear-free, non-contact and durable labyrinth seal with high thermal and chemical stability Process industry and general industry, e.g. gearboxes R35 Standard shaft seal for housings with a flange cover Heavy industry, e.g. rolling mills, ship propulsion, rudder units, tunnel boring machines, wind turbines R36 R37 R55 Standard shaft seal with additional radial lubrication grooves Heavy industry, e.g. rolling mills, ship propulsion, rudder units, tunnel boring machines, wind turbines Standard shaft seal with additional radial and circum- ferential lubrication grooves Heavy industry, e.g. rolling mills, ship propulsion, rudder units, tunnel boring machines, wind turbines Shaft seal with additional dust lip for large diameters, especially for use in wind tur- bines Heavy industry, e.g. rolling mills, ship propulsion, rudder units, tunnel boring machines, wind turbines R58 Standard shaft seal for grease lubricated bearings RS85 Self-retaining shaft seal for oil and grease lubricated bearings Heavy industry, e.g. rolling mills, ship propulsion, rudder units, tunnel boring machines, wind turbines Heavy industry, e.g. rolling mills, ship propulsion, rudder units, tunnel boring machines, wind turbines PRODUCT GROUP Labyrinth seals Merkel Radiamatic® 250

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® PTFE ‒80 … +200 No No I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B NBR HNBR FKM NBR HNBR FKM NBR HNBR FKM NBR HNBR ‒30 … +100 ‒20 … +120 ‒10 … +150 ‒30 … +100 ‒20 … +120 ‒10 … +150 ‒30 … +100 ‒20 … +120 ‒10 … +150 ‒30 … +100 ‒20 … +120 NBR ‒30 … +100 NBR HNBR FKM ‒30 … +100 ‒20 … +120 ‒10 … +150 Yes Yes Yes Yes Yes Yes, but without fab- ric Yes, but without fab- ric Yes, but without fab- ric Yes, but without fab- ric Yes, but without fab- ric Yes No S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 251 X E D N I

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Seals for Rotary Applications PRODUCT GROUP Merkel Radiamatic® Seventomatic® DESIGN DESCRIPTION MAIN APPLICATIONS RHS51 Self-retaining shaft seal for high-speed shafts Heavy industry, e.g. rolling mills, ship propulsion, rudder units, tunnel boring machines, wind turbines RPM41 Springless shaft seal for special applications, e.g. for work rolls in steel mills Heavy industry, e.g. rolling mills, ship propulsion, rudder units, tunnel boring machines, wind turbines S71 S73 S75 Innovative shaft seal for large, grease-lubricated roll- ing bearings Heavy industry, mainly for wind turbines Innovative shaft seal for large, grease-lubricated roll- ing bearings – with a sealing lip directed towards the outer diameter Innovative shaft seal for large, grease-lubricated roll- ing bearings – with addition- al dust lip Heavy industry, mainly for wind turbines Heavy industry, mainly for wind turbines Merkel® TBM TBM21 Special, large-size shaft seal without preload spring for heavy industrial applications Heavy industry, e.g. tunnel boring machines, pod drives in shipping, paper industry TBM27R Special, large-size shaft seal without preload spring for heavy industrial applications Heavy industry, e.g. tunnel boring machines, pod drives in shipping, paper industry 252

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® NBR HNBR FKM ‒30 … +100 ‒20 … +120 ‒10 … +150 Yes No NBR ‒30 … +100 Yes Yes HNBR ‒20 … +120 Yes Yes HNBR ‒20 … +120 Yes Yes HNBR ‒20 … +120 Yes Yes NBR HNBR NBR HNBR ‒30 … +100 ‒20 … +120 ‒30 … +100 ‒20 … +120 Yes Yes Yes Yes I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 253 X E D N I

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Seals for Rotary Applications DESIGN DESCRIPTION MAIN APPLICATIONS EA EAX High-performance water guard with constant line contact of the sealing lip, even with significant shaft misalignment High-performance water guard with constant line contact of the sealing lip, even with significant shaft misalignment Heavy industry, universally suitable for many applications Heavy industry, universally suitable for many applications WA8074 Polyurethane water guard with defined sealing lip Heavy industry, universally suitable for many applications WA-A Standard water guard type A (standard version) Heavy industry, universally suitable for many applications WA-AX Standard water guard type AX (version for significant shaft misalignment) Heavy industry, universally suitable for many applications WA-S Standard water guard type S (heavy, wide version) Heavy industry, universally suitable for many applications WA-L Standard water guard type L (small, uniform profile for all diameters) Heavy industry, universally suitable for many applications PRODUCT GROUP Merkel® Enviromatic Merkel® Water Guard Merkel® V-ring 254

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® NBR HNBR FKM NBR HNBR FKM ‒30 … +100 ‒20 … +120 ‒10 … +150 ‒30 … +100 ‒20 … +120 ‒10 … +150 Yes Yes Yes Yes PU ‒30 … +110 Yes Yes NBR FKM NBR FKM NBR FKM NBR FKM ‒30 … +100 ‒10 … +150 ‒30 … +100 ‒10 … +150 ‒30 … +100 ‒10 … +150 ‒30 … +100 ‒10 … +150 Yes Yes Yes Yes Yes Yes Yes Yes I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 255 X E D N I

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Seals for Rotary Applications SEALING CAPS PRODUCT GROUP Sealing caps DESIGN DESCRIPTION MAIN APPLICATIONS GA GSA Sealing cap with press fit – standard design (rubber out- side) Earthmoving equipment; industrial/forklift trucks; agricultural equipment; truck-mounted cranes Sealing cap with press fit – special design with rubber/ steel outside Drillings and assembly guides in housings; general mechani- cal engineering 256

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1. Product Overview MATERIAL MAX. TEMPERATURE STANDARD CATALOG FREUDENBERG RANGE [°C] * RANGE XPRESS® 75 NBR 99004 ‒40 … +100 75 NBR 99004 ‒40 … +100 Yes Yes No No I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P * Temperature specification applies to measurement at the seal. The temperature of the operating medium can differ! 257 X E D N I

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Seals for Rotary Applications 2. PRODUCT GROUPS 2.1 SIMMERRING® The name Simmerring® is a registered trademark of Freudenberg. The Simmer- ring® from Freudenberg Sealing Technol- ogies (hereinafter also referred to as FST) seals drive shafts and belongs to the radial shaft seal group according to DIN. REQUIREMENTS y reliable static and dynamic tightness y high functional reliability y compatibility with the media to be sealed y tolerance to external environmental influences y low friction y easy installation FST Website Simmerring® Product catalog 258

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2. Product groups FEATURES Simmerring® with elastomer outer casing, spring-loaded sealing lip and additional dust lip based on the terms in DIN 3761, 01/1984 version. Tension spring Spring retaining collar Spring groove 1. Outer surface 2. Face chamfer Face 3. Lining 4. 5. Fixing recesses 6. Diaphragm surface (outside) 7. 8. 9. 10. Contact surface (fluid side) 11. Sealing lip 12. Sealing edge plane 13. Face side 14. Bottom 15. Spring knit line 16. Sealing edge 17. Contact surface (air side) 18. Dust lip area (diaphragm side) 19. Dust lip 20. Dust lip area (air side) 21. Diaphragm area (inside) 22. Diaphragm 23. Bottom shell 24. Stiffening ring 25. Bottom surface 26. Bottom chamfer 27. Outer casing See also → chapter “Materials and Process engineering – 6. Carrier parts“, page 123. 1 2 3 4 5 6 7 8 9 10 11 12 Fluid side 13 14 27 26 25 24 23 22 21 20 19 18 17 16 15 Air side I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P Fig. 93 Characteristics of a typical Simmerring® 259 X E D N I

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Seals for Rotary Applications The main features of a Simmerring® fulfill the partial functions described below: y cylindrical outer surface (1) (→ Fig. 93) to ensure static sealing in the housing • made of elastomer with integrated OPERATING CONDITIONS The weighting of the requirements for each application and the operating con- ditions are decisive for the selection of the seal: metallic stiffening ring (24) y circumferential speed, i.e. diameter and • made of metal, mainly drawn or machined on the outer diameter (gluing may be necessary) y spring-loaded sealing lip (11) to ensure dynamic and static tightness on the shaft. Permanent further development has resulted in optimized sealing lip profiles to further increase reliability across a wide range of loads. y one or, in special cases, several dust lips (19) protect against the ingress of dirt and dust from outside. When using seals with a dust lip on the shaft, the maximum recommended circumferen- tial speed of 8 m/s must be observed. Higher circumferential speeds can also be achieved by modifying the design speed of the shaft y temperature y pressure y dirt accumulation from outside y dirt accumulation in the unit to be sealed y vibrations y media to be sealed • mineral oil and synthetic-based lu- bricating oils • mineral oil and synthetic based greases • other liquid, pasty and gaseous media whose compatibility with the gasket material must be ensured 260

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2. Product groups Play-circle  Application example BABSL/PPS APPLICATION AREAS Simmerring® are used to seal rotating shafts, predominantly in the following applications: y heavy industry (sealing of shafts in rolling mills, cement mills, large gear- boxes) y shipbuilding (sealing of stern tubes, thrusters, rudder drives) y internal combustion engines (sealing y units and manufacturing equipment of crankshafts and camshafts) in the process industry y electric motors y drive train in passenger cars and com- mercial vehicles (sealing of transmis- sions, differentials, axles, wheel hubs) y drive train in agricultural and con- struction machinery (sealing of gear- boxes, differentials, axles, wheel hubs) y industrial gearboxes (sealing of spur and worm gears, e.g. in production plants, robots or conveyor systems) y hydraulic power unit (sealing of hy- draulic pumps and hydraulic motors) y compressors y household and industrial washing machines The following illustrations contain stand- ardized sectional views of the seals. Their color representation does not represent any reference to the material used. The orientation of the seals shown does not necessarily correspond to the actual assembly position/orientation. Simmerring® BABSL Simmerring® PPS I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P Fig. 94 Pressure-loadable Simmerring® in hydraulic pumps and motors 261 X E D N I

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Seals for Rotary Applications Blind shaft Sealing cap GA Drive Simmerring® BA Alternative: Drive Simmerring® BAUM eCON Alternative: Output Simmerring® MSS3 (design for food applications) Output Simmerring® MSS1 Fig. 95 Simmerring® and sealing caps in industrial gearboxes 262

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2. Product groups Cassette seal CASCO Play-circle  Further designs for use in agricultural and construction machinery Further infor- mation in the CTI Seals Sales Sheet Special design for CTI application Simmerring® combi seal Simmerring® cassette seal Special shape with axial lip Fig. 96 Simmerring® in agricultural and construction machinery I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 263 X E D N I

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Seals for Rotary Applications Cassette seal CASCO (Diesel engine only) Simmerring® BAPTSLV Fig. 97 Simmerring® in internal combustion engines Play-circle  Application example MSS1 Simmerring® cassette seal Simmerring® MSS1 Simmerring® BAUMSL Fig. 98 Simmerring® in industrial robots 264 Cassette seal CASCO (Diesel engine only) Simmerring® BAUMSLV

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t h e s e a l i n g l i p F i g . 9 9 S i m m e r r i n g ® i n s p e c i a l a p p l i c a t i o n s w i i t h h g h s p e e d a n d l o w l u b r i c a n t s u p p l y t o l B u e S e a l i S m m e r r i n g ® 2 6 5 INDEX STUFFING BOX PACKINGS DIAPHRAGMS BOOTS & BELLOWS HYDRAULIC ACCUMULATORS SPECIAL SEALING PRODUCTS STATIC SEALS FLUID POWER APPLICATIONS – PNEUMATICS FLUID POWER APPLICATIONS – HYDRAULICS SEALS FOR ROTARY APPLICATIONS 2 . P r o d u c t g r o u p s INTRODUCTION & SERVICES MATERIALS AND PROCESS ENGINEERING

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Seals for Rotary Applications Drive shaft Radiamatic® HTS II Drive shaft Gerromatic Fig. 100 Product variants Radiamatic® HTS II and Gerromatic in food and beverage indus- try applications 266

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2. Product groups EXAMPLES OF SEALING ARRANGEMENTS Fig. 101 Back-to-back application for separation of two media (with vent hole between the seals at high circumferential speeds) Fig. 102 Back-to-back application for water from outside (if necessary, special version with stainless steel spring and stiffening plate in stainless steel) I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 267 X E D N I

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Seals for Rotary Applications Fig. 103 Sealing with grease lubrication (with greasing) Fig. 104 Sealing with oil lubrication 268

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2. Product groups Play-circle  Application example MSS1 Fig. 105 Sealing with shaft in the vertical position. Increased dirt accumulation at the sealing lip due to wear particles sinking in the medium Standard design e.g. Simmerring® BABSL Standard design e.g. Simmerring® BAUM Fig. 106 Sealing against vaccum (vacuum in left chamber, barrier fluid in mid chamber) I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 269 X E D N I

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Seals for Rotary Applications Alternative: Simmerring® MSS3 with PTFE disc Simmerring® B2PT Fig. 107 Sealing against aggressive media (example: pump) 270 Simmerring® BAUM Alternative: Simmerring® MSS3 with PTFE disc

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2. Product groups 2.2 RADIAMATIC® SHAFT SEALS The name Radiamatic® is a registered trademark of Freudenberg. Radiamatic® shaft seals are used primarily in heavy industry. Other product groups, such as Seventomatic®, Enviromatic or TBM seals, complement the range in this application area. REQUIREMENTS y reliable static and dynamic tightness y high functional reliability y compatibility with biodegradable lu- bricants y allowance of large shaft misalignment y mastering harsh environmental con- Product catalog Radiamatic® ditions y ozone or seawater resistance y joining of seals on site y service life of up to 20 years I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 271 X E D N I

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Seals for Rotary Applications FEATURES Fig. 108 shows the typical structure of a Radiamatic® radial shaft seal for use in heavy industry. The most important feature is the lack of a steel case, which allows the seal to be cut and rejoined during field assembly. A rubber/fabric back provides the neces- sary stability of the ring. A high-perfor- mance garter spring ensures permanent contact pressure of the sealing lip on the shaft. The optional dust lip is integrated into the sealing lip and functionally de- coupled in such a way that both lips don’t interfere during operation. open side usually in the direction of the operating medium closed side usually in the direction of the environment Garter spring Sealing edge Fig. 108 Typical structure of a Radiamatic® seal Static or adhesive part (rubber/fabric) Sealing lip (pure elastomer) Dust lip (optional) 272

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2. Product groups OPERATING CONDITIONS The expectations placed on seals for use in heavy industry are high. Above all, such seals should be robust and functionally safe. Leaks in a ship’s propulsion system are often immediately visible on the water surface and lead to shutdown or an immediate and costly dock stop. Maximum reliability is the main criterion. For exam ple, seals for the main bearing in tunnel boring machines. A failure there would lead to immense costs. In wind turbines, the focus is on other properties. Here, the seals must be ozone-resistant and achieve a long service life of up to 20 years. FLEXIBLE OF SERVICE The possibility of on-site assembly without time-consuming dismantling of the system is often another customer requirement for servicing. This means that seals are supplied open or cut open on site, placed around the shaft and reassembled to form an endless ring. For this reason, a self-retaining steel case is usually not used, and a flange cover fixes the seal ring axially in the housing. APPLICATION AREAS Radiamatic® shaft seals are used wher- ever large diameters have to be sealed, extreme ambient and operating condi- tions prevail, or high shaft misalignment has to be compensated. TBM seals for tunnel boring machines, for example, can have diameters of more than 10 m. FST manufactures such rings without a joint for maximum product quality. Typical applications in the field of heavy industry: y work rolls in steel mills y main bearing seals in wind turbines y pivot bearings in pod drives for marine applications y marine propulsion systems, rudder units, stabilizers, bow thruster y main bearing seals in tunnel boring machines y rollers in the pulp and paper industry y large gearboxes The following illustrations of typical app- lications contain standardized sectional views of the seals. Their color representa- tion does not represent any reference to the material used. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 273 X E D N I

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Seals for Rotary Applications Main bearing seal Seventomatic® S71 Main bearing or upstream seal (water guard) Enviromatic EA Fig. 109 Seventomatic® and Enviromatic product variants for use in wind turbines Sealing of the work roll Radiamatic® RPM41 Water guard Enviromatic Fig. 110 Radiamatic® and Enviromatic product variants for use in steel and rolling mills Source: SMS group 274

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2. Product groups Rudder unit Swivel column Stabilizers Bow thruster Radiamatic® R35 System TBM27R Radiamatic® R35 Radiamatic® R37 System Fig. 111 Product variants Radiamatic® and TBM radial shaft seals in undersea marine applications Main bearing TBM21 Fig. 112 TBM radial shaft seals in tunnel boring machines Source: Herrenknecht AG I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 275 X E D N I

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Seals for Rotary Applications EXAMPLES OF SEALING ARRANGEMENTS Fig. 113 Sealing system for the work roll in a steel mill, consisting of a Radiamatic® RPM41 double arrangement in combination with an Enviromatic water guard Fig. 114 Sealing system for tunnel boring machines with a multiple arrangement of TBM seals 276

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2. Product groups 2.3 SIMMERRING® CASSETTE SEALS PROPERTIES y high, medium and low protection against pollution y maximum 0.5 bar permissible on the oil side (depending on the geometry of the main sealing lip) y oil sealing and protection against con- tamination for various ambient condi- tions and speeds y integrated labyrinth to protect against y no axial movement permitted during dirt y easy installation; provides low risk of damage to the seal during installation y easy handling; provides low risk of damage to the seal during handling rotation y limited axial movement permitted during seal assembly Product catalog cassette seals I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 277 X E D N I

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Seals for Rotary Applications SIMMERRING® CASSETTE SEAL TYPE 1, 2, 3 PROPERTIES y speed from high to low, change from y increased protection against dirt, change from type 1 to type 3 y seal for both directions of shaft rota- tion y diverse application possibilities in type 1 to type 3 practice y more complex labyrinth, change from type 1 to type 3 Sealing lip for oil/grease sealing Socket with special surface treatment Inner diameter with elastomer layer Fig. 115 Simmerring® cassette seal type 3 Outer diameter: Elastomer for high static tightness Metal for reliable assembly alignment Inner labyrinth profile for dust-/water retention Axial buffer to maintain the reciprocal position of the two components during assembly Pregreased chambers Cassette Seal Typ 3Simmerring® cassette seal Fig. 116 Simmerring® cassette seal in driven axles 278

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2. Product groups SIMMERRING® CASSETTE SEAL TYPE 4 PROPERTIES y less limitation on speed, temperature and pressure compared to cassette seal type 3 y extremely high protection against dirt y seal for both directions of shaft rota- tion y extended applicability in the field, due to the improved application pos- sibilities in highly contaminated envi- ronments Axial buffer to maintain the reciprocal position of the two components during assembly Sealing lip for oil/grease sealing Socket with special surface treatment Inner diameter with elastomer layer Fig. 117 Simmerring® cassette seal type 4 Outer diameter: Elastomer for high static tightness Metal for reliable assembly alignment Internal labyrinth profile for dust/water retention Pregreased chambers Simmerring® cassette seal type 4 I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P Fig. 118 Use of the Simmerring® cassette seal 279 X E D N I

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Seals for Rotary Applications SIMMERRING® CASSETTE SEAL HS y good protection against pollution y seal for only one or both directions of shaft rotation PROPERTIES y inner diameter of metal and elastomer y high speeds and temperatures permis- y oil/grease sealing at high rotational speeds and temperatures y for high heat dissipation from the seal- sible Outer diameter: Elastomer for high static tightness Sealing lip for oil/grease sealing Working surface of the sealing precision trimmed Inner diameter: Metal content for better heat dissipation ing edge Pregreased chamber Outer diameter: Metal for reliable assembly alignment Inner labyrinth profile for dust/sludge retention Pregreased chambers Fig. 119 Simmerring® cassette seal HS (high speed) Simmerring® cassette seal Cassette HS HS Fig. 120 Use of the Simmerring® cassette seal as a pinion seal in axles 280

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2. Product groups SIMMERRING® CASSETTE SEAL CASCO y high speeds and temperatures permis- sible y seal for only one direction of shaft ro- PROPERTIES y axial sealing lip: extremely low wear and tation (CW or CCW) y protection against pollution low friction y low sensitivity to axial/radial eccen- tricity Axial sealing lip Inner diameter: Metal content for reliable assembly Fig. 121 Simmerring® cassette seal CASCO Outer diameter: Elastomer for high static tightness Metal for reliable assembly alignment Hook lip for catching Inner labyrinth profile for dust/sludge retention I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P Fig. 122 Use of Simmerring® cassette seals CASCO on the crankshaft 281 X E D N I

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Seals for Rotary Applications 2.4 SIMMERRING® COMBI SEALS Product catalog combi seals PROPERTIES Simmerring® combi seals are “unitized” seals for medium speeds and for im- proved protection against contamination from the environment. They tolerate axial misalignment of the shaft during rotation. They consist of: y a sealing ring (standard design or design BA DUO) y a dirt repellent made of polyurethane y a “Unitized” housing SIMMERRING® COMBI SEAL SF19 y higher axial shaft misalignment per- PROPERTIES y more flexible dirt deflector made of poly urethane that follows the wave dynamics y integrated elastomer dirt deflector, which is the first element to prevent dirt from entering the housing missible y very high protection against contam- ination y for environments with high require- ments Outer diameter: Metal for reliable assembly alignment Rubber sealing lip for oil/grease from the inside Inner elastomer dust lip against water/dust from the outside Fig. 123 Simmerring® combi seal SF19 Outer diameter: Elastomer for high static tightness Dirt wiper, which is the first component that protects against the penetration of dirt Dirt deflector made of compact polyurethane against water/dust from outside 282

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2. Product groups SIMMERRING® COMBI SEAL SF21 PROPERTIES y optimized shape of the dirt deflector made of high-quality polyurethane, which is now more sensitive to the ec- centricity of the shaft and enables better tracking of the shaft y higher axial shaft misalignment per- missible compared to SF5, SF6, SF8 y integrated dirt deflector made of hardened elastomer compound, which is the first element to prevent dirt from entering the housing y higher protection against dirt com- pared to SF19 y for harshest environments Outer diameter: Metal for reliable assembly alignment Rubber sealing lip against oil/grease from inside Inner dust lip from elastomer against water/dust from outside Fig. 124 Simmerring® combi seal SF21 Outer diameter: Elastomer for high static tightness Outer wiper made of hardened composite material, as the first component it protects against the penetration of dirt Dirt deflector made of high-quality, compact Freudenberg polyurethane with optimized shape for better shaft tracking properties I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 283 X E D N I

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Seals for Rotary Applications SIMMERRING® COMBI SEAL SF22 PROPERTIES y optimized shape of the dirt deflector made of high-quality polyurethane, which is now less sensitive to eccen- tricity of the shaft and allows better tracking of the shaft y counter-rotating solution allows highest permissible axial shaft misalignment y integrated dirt deflector made of hard- ened elastomer compound, which is the first element to prevent dirt from entering the housing y higher protection against dirt com- pared to SF19 y for harshest environments combined with demanding axial misalignment Outer diameter: Metal for reliable assembly alignment Rubber sealing lip for oil/grease from the inside Counter rotating solution enables increase of the permissible axial play of the shaft Outer diameter: Elastomer for high static tightness Outer wiper made of hardened composite material, which is the first component that protects against the penetration of dirt Dirt deflector made of high-quality, compact Freudenberg polyurethane with optimized shape for better shaft tracking properties Inner dust lip made of elastomer against water/dust from outside Fig. 125 Simmerring® combi seal SF22 Simmerring® combi seal Fig. 126 Simmerring® combi seal in driven axle 284

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3. Sealing mechanism using the example of the Simmerring® 3. SEALING MECHANISM USING THE EXAMPLE OF THE SIMMERRING® The Simmerring® seals a shaft against the housing of a device (e.g. → Fig. 94, page 261 and → Fig. 95, page 262): • decomposition products • lubricant supply • internal contamination y dynamic and – when the shaft is at standstill – static sealing between sealing lip and shaft y static sealing and ensuring a tight fit of the seal between the outer jacket of the seal and the housing bore Environment and operation y temperature y dust and dirt y run and shutdown periods y cleaning media 3.1 INFLUENCING PARAMETERS The sealing behavior and the service life of the seal are influenced by a complex system of mutually influencing variables: The device to be sealed y shaft • diameter • speed • eccentricity • surface • axial movement • material • manufacturing process • chamfer design • hardness • coating y housing • surfaces • center offset to the shaft • tolerances • material • installation space • chamfer design y medium • temperature • chemical effects • viscosity • lubricity • pressure The Simmerring® y design and tolerances • of the adhesive part • of the sealing lip y radial force y material • hardness • wear resistance • resistance to chemical swelling and shrinkage • friction properties • sealing ability etc. 3.2 DYNAMIC SEALING FUNCTION The most important functional area of the Simmerring® is the sealing edge in contact with the surface of the rotating shaft (→ Fig. 127). The sealing mechanism in the contact area of the sealing lip is of decisive impor- tance for the sealing function. It is depend ent on a tribological system, (seal, shaft, and medium) as well as: y the design of the sealing lip y the properties of the elastomer mate- rial y the nature of the shaft surface y the medium to be sealed y the operating conditions (e.g. height impact, vibrations, kinematics ...) I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 285 X E D N I

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Seals for Rotary Applications Oil side Width of sealing gap Shear Height of the sealing gap Dirt Grease Fig. 127 Contact zone between sealing edge and shaft of a Simmerring® CHARACTERISTICS OF THE SEALING LIP A wide range of experience is required for dimensioning the characteristic values. The dimensioning is carried out by the manufacturer depending on the material, size, geometry and application of the Simmerring®. Geometrical parameters Overlap (→ Fig. 128) The inner diameter of the sealing lip is always smaller than the shaft diameter in the free, untensioned state. Radial force FR Air side β Oil side α hF Diameter in the free state shaft diameter d Fig. 128 Dimensions at the profile of the sealing lip 286 The overlap (also preload) is the difference between these two dimensions and is between approx. 0.8 mm and 2.5 mm, depending on the shaft diameter. The radial pre-load tuning of the geometry influences the flexibility of the lip: y flexible and long sealing lips for high tolerances of coaxiality and concen- tricity (for permissible values, see → Fig. 151, page 328 and → Fig. 152, page 329) y short profile with position stabilization relative to the shaft for pressure appli- cations The characteristic value for the distance between the center point of the spring and the sealing edge is the spring effec- tive distance hF: y if the hF dimension is too small, the lip may tip over, especially in the case of shaft run-out and non-flat installation y a too large hF dimension results in a deflection of the lip and thus a wide contact of the lip with the shaft as well as a wide running track

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3. Sealing mechanism using the example of the Simmerring® Sealing lip angle The sealing lip angles influence the seal- ing mechanism by acting on the contact pressure ratios: y oil side: steep angle α y air side: flat angle β Radial force The radial vector force exerts an angular pressure on the shaft due to the expan- sion of the sealing lip in the installed state. This sum of tangential tensile and bending forces of sealing lip and spring is determined by the: y influence of the elastomer: The mod- ulus of elasticity depends on the ma- terial, temperature and aging. Thus, the decrease of the radial force during operation depends on temperature, time and possible interactions with the medium to be sealed (→ chapter “Materials and Process engineering – Anti-Ageing Agents“, page 109 y influence of the sealing lip profile: Sealing lip geometry and elongation, i.e. overlap y influence of the tension spring: mate- rial (standard material: spring steel wire EN 10270-1-SM, in special cases stainless steel according to EN 10270-3), temperature, length, coil diameter, wire thickness A low radial force value should be striven for in order to keep friction and wear of the seal low. However, a minimum radial force is required to ensure the dynamic sealing function over the long term. Sealing function in the contact zone of the sealing lip The radial force of the sealing lip, in con- junction with the dimensioning of the sealing lip angle and effective spring dis- tance, pro duces an asymmetrical or bias contact pressure distribution (→ Fig. 129): y pressure maximum and steep rise on the oil side y flat drop on the air side Radial force FR Radial force FR Oil side Air side Oil side Air side Sealing lip Sealing lip pmax Contact pressure distribution pmax Direction of shaft rotation Fig. 129 Deformation structure of the elastomer in the contact surface of the sealing lip I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 287 X E D N I

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Seals for Rotary Applications This deformation structure, together with the rotating shaft, generates a pumping effect on the medium to be sealed in the direction of the oil side. This micropump effect is decisive for the seal- ing function. 3.3 SEALING LIPS WITH HELIX (SPECIAL DESIGN) To increase the sealing capacity at high temperatures and circumferential speeds, the air side of the sealing lip is provided with a helix for special designs (→ Fig. 130). This asymmetrical distribution of contact pressure is of great importance for the function of the seal. The contact pressure distribution and the circumferential force generated by the rotating shaft lead to a characteristic deformation structure of the contact surface of the seal lip (→ Fig. 129). A suitable elastomeric material for the seal is characterized by the formation of a distinct structure of the “distortion”. The structures that promote the micro- pumping effect are formed at the seal edge during the run-in. Therefore, a run- ning-in or wear-in phase is necessary for the seal to generate the surface roughness required for the pumping effect. This is why both the upper and lower shaft sur- face-finish must be controlled. Oil side Sealing edge Direction of rotation of the shaft seen from the air side of the seal: right = RK right helix left = LK left helix WK Bi-directional helix Pumps with direction of rotation to Pumps with direction of rotation to the right towards the oil side the left towards the oil side Fig. 130 Helix on the air side of the sealing lip (β) 288

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3. Sealing mechanism using the example of the Simmerring® Map-Marker-Exclamation Always avoid dry running Angled helix ribs oriented in the direction of rotation extend into the contact zone of the sealing lip. They reinforce the pumping effect of the micro-lead of the elastic material. Since the orientation of the ribs of the single helix is tied to a direction of rota- tion, an arrow on the bottom side of the helix rings indicates the permissible di- rection of rotation. If use for both directions of rotation is nec- essary, bi-directional helix is used. This is less effective than the uni-directional helix. All helix rings have a finished sealing edge, i.e. produced in the forming tool. Radial shaft seals with return helix cannot be used reliably in combination with pres- surization on the medium side. Standard Simmerring® from the catalog program are designed without return helix. Simmer- ring® seals with a machined sealing edge (e.g. BAUM profile type) exhibit stable seal- ing behavior and therefore do not require return helix structures. 3.4 LUBRICATION AND FRICTION Sufficient supply of lubricant to the seal is decisive for the service life and reliabil- ity of the seal. The better the lubricating and wetting properties of the fluid to be sealed, the lower coefficient of friction, and the lower the wear. The greater the supply of lubricant for the sealing edge, the lower the temperature in the sealing gap between the sealing edge and the ro- tating shaft surface. Even at standstill, the fluid to be sealed and at the same time used for lubrication penetrates the unevenness of the shaft and sealing lip due to capillary forces. The direct contact of the sealing lip with the shaft is predominant. Starting and then increasing rotational movements lead, similar to a sliding bear- ing, from the state of boundary friction via mixed friction to predominant hydro- dynamic friction. Important note! Elastomer seals must never run dry. When installing elastomer seals, the shaft or the seal must be lightly greased or oiled. For applications with fluids that have limited lubricating properties (e.g. water), individual technical advice should be obtained from FST. During the design phase, it should be en- sured that sufficient lubricant is available at the sealing edge during the first revo- lutions (e.g. through holes and channels). Some types of rolling bearings, including tapered roller bearings, can generate a considerable pumping effect during op- eration. As a result, different fluid supplies are possible relative to the sealing point, which can have a negative influence on the lubrication of the sealing edge. Remedy: design measures to ensure sufficient lubricant supply to the sealing point under all operating conditions and installation positions. Parameters influ- encing the contact pressure of the seal- ing edge on the shaft surface and the lubrication conditions at the sealing lip affect the friction performance of the sealing point. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 289 X E D N I

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Seals for Rotary Applications The minimum friction power is deter- mined by the minimum contact pressure of the sealing lip, which ensures the dy- namic sealing function of the sealing point. Optimum seal performance and life-cycles are achieved by precisely tun- ing in the seal design to the application parameters. The reference values for friction power were determined with complete lubri- cation of the sealing lip (→ Fig. 131). The values given here only indicate the order of magnitude of the friction and refer to a well-lubricating engine oil. They can therefore not be used as absolute values for individual cases and are not transfer- able to applications with industrial gear oils. The constant demand for low friction and at the same time reliable sealing function requires the continuous further development of sealing materials and seal design. ] s t t a w [ r e w o p l a n o i t c i r F 400 300 200 100 0 0 m m 0 6 3 Ø m m 0 2 3 Ø m m 0 0 4 Ø aft h S U/min 0 0 5 m m 0 28 Ø U/min 0 0 0 1 min / U 0 5 2 d e e p S m m 200 Ø m m 160 Ø mm 140 Ø mm 120 Ø U/min 0 0 0 2 3 000 U/min 4 000 U/min 6 000 U/min 8 0 0 0 U/min 1 0 0 0 0 U / m in U / m i n 0 0 0 U / m i n 0 0 5 1 0 0 2 100 m m Ø m 80 m Ø m m m m m m 0 0 0 0 m m 6 5 4 3 2 0 m m Ø Ø Ø Ø Ø 1 0 m m Ø 5 10 15 20 25 Circumferential speed [m/s] Fig. 131 Reference values for the frictional power of a Simmerring® without dust lip in SAE 20 engine oil, at T = +100 °C, example: Shaft Ø d1 = 80 mm, speed n = 3,000 rpm, friction power approx. 150 W 290

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3. Sealing mechanism using the example of the Simmerring® 3.5 STATIC TIGHTNESS AND y chamfers on the adhesive part (see FIT IN THE BORE The outer casing (also known as the ad- hesive part) of the Simmerring® has the following tasks: y static sealing in the housing bore y ensuring a tight fit in the bore y enabling proper and easy installation of the seal Depending on the installation conditions and operating conditions, different versions of the adhesive part are used (→ Fig. 132). For trouble-free assembly, the following points must be taken into account: DIN 3760) y press fit allowances to the nominal dia- meter depending on the design of the outer surface according to DIN 3760 For requirements on the design of the housing bore, refer to section 8.2 “Design of the housing” (→ page 331). Simmerring® with rubber covered outer di- ameter – Type BA (A according to DIN 3760) y offers the best conditions for static sealing y for split housings y for housings made of light metal with increased thermal expansion y for pressure applications y for low-viscosity and gaseous NOMINAL HOUSING Ø [mm] PRESS FIT ALLOWANCE FOR METALLIC OVERLAP FIT PRESS FIT ALLOWANCE FOR ELASTOMER OVERLAP FIT [mm] [mm] > 0 35 50 80 120 180 300 400 ≤ 35 50 80 120 180 300 400 500 Smooth fit, fine and medium creasing Coarse creasing 0.23 ±0.08 0.23 ±0.08 0.28 ±0.08 0.28 ±0.08 0.35 ±0.10 0.35 ±0.10 0.43 ±0.13 0.43 ±0.13 0.30 ±0.10 0.30 ±0.10 0.35 ±0.10 0.35 ±0.10 0.43 ±0.13 0.43 ±0.13 0.50 ±0.15 0.50 ±0.15 0.15 ±0.05 0.15 ±0.05 0.18 ±0.05 0.20 ±0.05 0.23 ±0.05 0.25 ±0.05 0.29 ±0.06 0.29 ±0.06 Tab. 13 Typical overlap fit allowance for designs B1, B2 and BA based on DIN 3760, part 1 as of 09/1996 I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 291 X E D N I

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Seals for Rotary Applications Map-Marker-Exclamation Care must be tak- en to prevent any adhesive material from coming in contact with the sealing lip Simmerring® with rubber covered outer diameter – Type BA...X7 outer diameter with grooves y enables easy assembly y reduces the possibility of retracting or skewing the seal y enables higher press-fit allowance to increase the safety of the static seal, especially in housings with high thermal expansion Simmerring® with partially rubberized outer diameter – BD design (special design on request – not part of catalog range) combines the advantages of reliable static sealing by the elastomeric part with press fit by the metallic part of the outer diameter Simmerring® with metallic outer diame- ter – Type B1 and B2 (B/C to DIN 3761) Production of the metallic, smooth outer surface by deep drawing and possible finishing by turning or grinding. To coun- teract corrosion, a corrosion protection oil is applied to finished components: y for requirements of particularly tight and exact fit in the bore y important note: In unfavorable condi- tions such as • rough bore surfaces • low viscosity and creeping media or • pressure applications • the use of an additional sealing com- pound (adhesive) may be necessary in the contact area of the press fit y limited use only in housings with in- creased thermal expansion or split housings y when pressed into light metal housings, there is a risk of scoring in the bore y Type B2 (with additional stiffening ring) has higher structural integrity and radial stiffness for: • larger dimensions • difficult and awkward installations Material of the metal stiffening part and the metal housing y for all standard applications: non-alloy steel DIN EN 10027-1 y for special cases: stainless steel DIN EN 10088 BA Outer diameter covered with elastomer Very good static sealing function B1 Outer diameter of the plate girder without elastomer covering Limited static sealing function B2 Outer diameter without elastomer covering 2 sheet metal supports for high stability Limited static sealing function BD Outer diameter with elastomer seat and metal seat Customized design Fig. 132 Designs of the adhesive part of the Simmerring® 292

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4. MEDIA TO BE SEALED 4. Media to be sealed Map-marker-edit No disclosure of test results using various test programs to determine, among other things, the lubrication and wetting behavior of the tested fluid (→ “13. Simmerring® Engineering”, page 401). The client is the owner of the test results. Test results can therefore not be passed on to third parties. Against this back- ground, the lubricant manufacturer (customer) can, if necessary, provide in- formation on tests carried out. 4.2 INTERACTIONS BETWEEN FLUIDS AND ELASTOMER MATERIALS The chemical/physical effects of the media on the sealing materials have a decisive in- fluence. The reactions or interactions are accelerated, especially with increasing tem- perature (see also → chapter “Materials and Process engineering – Influence of media: Storage tests“, page 154 and → chapter “Materials and Process engineer- ing – 12. Chemical resistance“, page 180). The materials can harden or soften under the influence of media (→ Fig. 133) (see also → “12. Failure analysis”, page 381): y hardening due to aging processes caused by the media, especially at el- evated temperature y softening by swelling due to the influ- ence of the media 4.1 FLUID AND MATERIAL SELECTION The fluid to be sealed largely determines the selection of the material and thus also the design of the radial shaft seal. Sealing is possible against liquid, pasty and, in exceptional cases, gaseous media. Sealing against lubricants, e.g.: y mineral oils y synthetic oils y mineral oil-based greases y synthetic greases Sealing against working fluids, e.g.: y hydraulic oils according to DIN 51524 y fire-resistant hydraulic fluids according to VDMA 24317 and VDMA 24320 y silicone oils with minimal lubricating properties Sealing against aggressive media with low lubricating properties (in special cases), e.g.: y acids y lyes y organic solvents The constantly increasing load on the device due to higher power density has resulted in permanent adaptation and new development of the lubricants. Seal- ing compatibility is a decisive criterion here. Freudenberg Sealing Technologies offers to perform oil compatibility tests. As part of the release tests, static insertion tests are carried out to determine the chemical and physical interactions. In addition, dy- namic tests with oil seals are completed I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 293 X E D N I

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Seals for Rotary Applications ] % [ e g n a h C An initial, often sufficiently accurate, as- sessment of the effect of the media to be sealed on the elastomer material is made by determining the mechanical values on test samples in the laboratory. Before and after static immersion of a standardized elastomer test sample in the corresponding fluid, values such as hardness, elongation at break, tensile strength and volume are measured and the change documented (DIN 53521). The influence of different lubricants, especially under the influence of high temperature, is clearly illustrated by the example of the change in elongation at break, (modulus of elasticity) (→ Fig. 134). In order to assess the service life of a par- ticular elastomer material and thus of a seal, a change in elongation at break < 50% is taken as a guide value. For more information, see also → chapter “Materials and process engineering – 8. Testing methods“, page 143. +20 0 ‒20 ‒40 ‒60 ‒80 ‒100 Hardness Volume Tensile strength Elongation at break 0 200 400 600 800 1000 Storage time [h] Fig. 133 Change in characteristic values of an NBR material as a function of storage time; storage in SAE 80 gear oil at +100 °C 294

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4. Media to be sealed in ever newer combinations. As a result, static and dynamic compatibility testing with elastomer materials is becoming increasingly important. In this context, Freudenberg Sealing Technologies recom- mends observing the specific information provided by oil manufacturers and, in case of doubt, checking compatibility with the selected materials. 4.3 MINERAL OILS y used in motor vehicles according to API and MIL classifications: engine oils, manual transmission oils, hypoid transmission oils, ATF oils for automatic transmissions y used in a wide range of applications in gear manufacturing: C, CL, CLP gear oils according to DIN 51517 Low-alloy mineral oils generally show good compatibility with the materials used for Simmerring®. Increasing demands on the mineral oils lead to higher additivated oils ] % [ k a e r b t a n o i t a g n o e n l i e g n a h C +20 0 ‒20 ‒40 ‒60 ‒80 ‒100 Change of elongation at break = ‒50% Multipurpose grease Hypoid gear oil 85 W 90 ASTM oil No. 1 Air Gear oil SAE 80 Multigrade engine oil 15 W 40 0 200 400 600 800 1000 Storage time [h] Fig. 134 Exemplary representation of the change in elongation at break of NBR when stored in various fluids at +100 °C I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 295 X E D N I

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Seals for Rotary Applications Hypoid gear oils High-pressure lubricating oils with a pro- portion of special additives, especially EP additives, are used to improve lubricity and prevent seizure of bearings and gears. Additives are used to optimize the tribolog- ical processes in the area of tooth flanks in gear teeth and the contact points in bear- ings. However, these additives can also lead to deposits in the area of the sealing point at the sealing edge and the shaft surface. In addition, undesirable reactions in the tribological system of the sealing point may occur under certain circum- stances. Remedy: For the use of highly additivated lubricants, there are specially adapted elastomer materials or designs/products. The standard material 72 NBR 902 is largely insensitive to hypoid oils if the temperature of the fluid does not exceed +80 °C (→ Tab. 15, page 301). FKM materials can withstand higher ther- mal loads and are more chemically resist- ant to various hypoid oil substances. Sim- merring® made of 75 FKM 585 - BAUM, BAUMSL or special designs – can be used up to the specified temperature limits. The FST materials experts will be pleased to help with any queries. If possible, the sealing lip of the selected design should be designed for low fric- tion. This reduces the increase in temper- ature in the area of the sealing edge and the tendency for deposits to form in the sealing edge area. 4.4 SYNTHETIC LUBRICANTS Reasons for using partially and fully syn- thetic lubricants (→ Tab. 15): y better viscosity behavior y suitable for higher temperatures y good aging resistance y higher efficiencies Base oils generally show good compati- bility. However, in combination with the additives used, different interactions with the elastomer materials used are possible. When used with the material 75 FKM 585 and synthetic lubricants (especially poly- glycol oils), increased sealing edge wear may occur in the oil sump temperature range of below +60 °C. In this special application, a special FKM material (e.g. 75 FKM 170055) should be provided. The FST materials experts will be pleased to help with any queries. Important note: Before using lubricant- elastomer combinations in series pro- duction or under operating conditions that are not yet known, it is recommend- ed to carry out a trial or compatibility test. The first step should be a static laboratory test according to DIN 53521 over at least 168 h (preferably 1,008 h). Reliable infor- mation on the compatibility of fluid and elastomer can only be provided by per- forming a dynamic compatibility test lasting 1,008 or 2,016 hours, as has been shown in many cases. The intensive co- operation between seal and lubricant manufacturers has proven valuable here. Map-marker-edit For highly additi- vated lubricants, the temperature limits of 72 NBR 902 are restricted. Map-Marker-Exclamation Use of unknown combinations 296

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4. Media to be sealed I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I DEVELOPMENT OF THE DEVICE CHANGE OF INFLUENCES y Improved efficiency y Longer service life y Noise reduction y Lifetime lubrication y Extended lubrication intervals y Higher speeds y Higher temperatures y Higher mechanical stress on the components y Increased oil contamination y High acceleration DEVELOPMENT OF SYNTHETIC OR SEMI-SYNTHETIC, HIGHLY ADDITI- VATED LUBRICANTS y High temperature resistance y Aging resistant y Improved VI behavior y Good cold flow properties y Good solubility y Biodegradable oils Fig. 135 More demanding sealing point INCREASING DEMANDS ON SIMMERRING® y Thermal y Mechanical y Chemical/physical y Better dirt seal 4.5 LUBE & SEAL The demands on sealing systems are con- stantly increasing (→ Fig. 135). It is there- fore necessary to continuously investi- gate the influencing parameters. This is being done at Freudenberg Sealing Tech- nologies in close cooperation with Klüber, the in-house lubricant specialist based in Munich. The aim of the “Lube & Seal” pro- ject is to use optimally matched sealing material and lubricant (see also → chapter “Services – Lube & Seal”, page 12: y optimized chemical/physical interac- tions between elastomer and lubricant y minimized friction and thus of power loss y minimized wear y increased reliability y increased the service life 4.6 GREASES For sealing against grease, the conditions for dissipating frictional heat are less favorable than for liquid media. Remedy: If the circumferential speed exceeds approx. 50% of the permissible values for grease (material 72 NBR 902, → Fig. 136, page 310), consider switch- ing to oil lubrication. For the sealing of grease- lubricated, slowly running shafts, it is recommended that the space be filled as completely as possible with grease in accordance with the specifica- R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B Map-marker-edit Possible conversion to oil lubrication S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 297 X E D N I

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Seals for Rotary Applications 4.8 CONTAMINANTS IN THE FLUID TO BE SEALED Impurities can be, for example: y molding sand residues or metal chips from the production of cast housings y abrasion of rotating parts, e.g. of bronze worm wheels in worm gears y decomposition products from the fluids Depending on the load, these contami- nants influence the sealing and wear be- havior of the seals. Remedy: ensure that the housing is as clean as possible. If con- tact of the sealing lip with contaminants is unavoidable (e.g. in the case of vertical shafts), a collecting or centrifugal plate should be connected in series and a series seal used. In many applications, the MSS1 design with its upstream sinusoidal seal- ing lip on the fluid side has proved suc- cessful. tions of the bearing manufacturer. In ap- plications with relubricating systems (e.g. lubricating nipples), it is advisable, with regard to sealing capacity and low wear, to install the seal on one side of the bear- ing arrangement so that the sealing lip faces outwards (note: do not use a seal with a dust lip at this sealing point). In this way, overpressure in the sealed space can be avoided in the event of heating during operation or relubrication. For sealing with insufficient lubricant supply or against poorly lubricating media such as water or washing lye, a separate grease reservoir must be provided to lubri- cate the sealing and dust lip. The volume in the space between the sealing lip, dust lip and shaft should be filled approx. 40% with grease. Greases with a high oil separating capac- ity are particularly suitable for lubricating the sealing liprolling like bearing greases of consistency class NLGI 1 or NLGI 2 ac- cording to DIN 51818 with a minimum rolling penetration of 310 or 265 accord- ing to DIN 51804 or ASTM D217-52. 4.7 AGGRESSIVE MEDIA For the sealing of aggressive media, such as y acids, alkalis y silicone oils for viscous couplings y chemical resistant fluorinated oils, the resistance to the seal material must be clarified in each case (→ “5. Materials”, page 299). 298

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5. MATERIALS 5. Materials The selection and use of the material for the sealing lip are the most important criteria for the function and reliability of the sealing system. The properties of the individual materials are defined in speci- fications for the minimum or maximum physical values and their change after specified tests,. e.g. ASTM 2000. The de- cisive factor for the function, the sealing ability, can only be ensured by intensive and wide-ranging tests or within the framework of experience from series applications.. See also → chapter “Materials and Process engineering – 3. General material selec- tion and descriptions“, page 48 I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P NBR HNBR FKM PTFE ACM PU Steering S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B Engines Axles, gears Industrial gearboxes Hydraulic power units Heavy industry Process industry Washing machines Further mechanical engineering Standard material Special material Not used State of the art Trend Tab. 14 Application areas of materials for radial shaft seals S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 299 X E D N I

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Seals for Rotary Applications ACM POLYACRYLATE ELASTOMER Special material for use primarily in auto- motive engineering; on request. ACM is characterized by good properties in applications with high vibration loads. FKM FLUOROELASTOMER Preferably used for high chemical and thermal resistance requirements and generally for high circumferential speeds (→ Fig. 136, page 310), e.g. in y heavy industrial applications y two-stroke engines y engines in general y gearboxes, hydraulic power units y drive train of commercial vehicles y drive train of agricultural and con- struction machinery Broad range of applications and has longer expected service life compared to NBR materials. For material variants, media resistance and temperatures, see → Tables “Stand- ard/Special Materials for Simmerring®,” “Materials for Heavy Industry,” “Materials for Process Industry Applications” starting on page 302. HNBR HYDROGENATED NBR ELASTOMER HNBR is more heat resistant than NBR. In addition, HNBR offers better wear behav- ior than NBR in dynamic applications. HNBR is also resistant to hot water and shows good low-temperature and high-temperature behavior from ‒40 to +140 °C. In sealing technology, the signif- icantly more cost-intensive material HNBR is used primarily where higher tempera- tures and/or mechanical strength are re- quired. HNBR offers wide-ranging appli- cation possibilities, particularly in the process industry. HNBR is suitable in the process industry, the beverage industry and applications in contact with very greasy media. NBR NITRILE BUTADIENE ELASTOMER Widely used in mechanical engineering and heavy industry, in industrial gear- boxes, hydraulic power units (hydraulic pumps, hydraulic motors), two-stroke engines, washing machines and partly in the drive train of agricultural and con- struction machinery. For material variants, media resistance and temperatures, see overviews starting on page 302. PTFE POLYTETRAFLUOROETHYLENE The thermoplastic, non-polar polymer has a number of advantages that make it unique in sealing technology: y highly resistant to chemicals y very low coefficient of friction y can be used over a very wide temper- ature range without any problems y favorable dry running behavior y individual compounds have best di- electrical properties (conductive PTF E compounds on request) 300

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5. Materials PU POLYURETHANE Increasingly used in heavy industry due to positive properties such as: y high sealing effect y good friction behavior y robust, easy handling The properties of the various materials determine their most important areas of application (→ Tab. 14): PROPERTIES NBR HNBR FKM PTFE ACM PU Abrasion resistance Good Very good Very good Moderate Moderate Very good High temperature resistance Moderate max. +100 °C Good max. +140 °C (max. +100 °C continuous temperature) Very good max. +200 °C (max. +160 °C continuous temperature) Very good max. +200 °C (max. +160 °C continuous temperature) Good (max. +140 °C continuous temperature) Moderate max. +110 °C Low temperature resistance Down to –40 °C Down to –40 °C Down to –25 °C Down to –80 °C Down to –30 °C Down to –30 °C Oil resistance Good Good Very good Very good Good Good Tab. 15 Properties of elastomer materials Important notes: High temperature resistance refers to the maximum temperature resistance of the material in question. It is NOT the maximum operating temperatures (e.g. oil sump temperature or ambient tempera- ture). Low temperature resistance refers only to a limited extent to the minimum application temperature. The application is very much dependent on the viscosity of the fluid to be sealed at low tempera- tures, the radial runout of the shaft and other operating conditions (→ “6.4 Sealing behavior at low temperatures”, page 119). I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 301 X E D N I

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Seals for Rotary Applications 5.1 STANDARD MATERIALS FOR SIMMERRING® MATERIAL Color Density [g/cm3] (DIN 53479) Hardness [Shore A] (DIN 53505) Stress value/ 100% [N/mm2] Tensile strength [N/mm2] Elongation at break [%] (DIN 53504) (DIN 53504) > 10 (DIN 53504) > 300 – – – – – – 72 NBR 902 75 FKM 585 1) 75 FKM 595 1) PTFE 10/F56101 Dark brown Auburn Dark gray Blue 1.43 75 > 4 2.06 75 > 4 > 10 > 175 2.01 75 > 3.5 7.5 > 200 Classification according to ASTM D 2000 M2 BG 710 M2 HK 710 M2 HK 810 Temperature range at sealing lip [°C] –40/+100 –30/+200 –30/+200 –80/+200 MEDIA TO BE SEALED WITH INDICATION OF PERMANENT TEMPERATURE [°C] ASTM D 2000 M2 BG 710 M2 HK 710 M2 HK 810 M2 HK 710 – M2 BG 710 Permissible low temperature –40 –30 –30 –30 –80 –40 +100 +100 +80 +100 +100 1) 1) +150 +150 +140 +150 +150 1) 1) +150 +150 +140 +150 +150 1) 1) +150 +150 +140 +150 +150 1) 1) +150 +150 +140 +150 +150 1) 1) +100 +100 +80 +100 +100 1) 1) Mineral lubricants Engine oils Gear oils Hypoid gear oils ATF oils Greases Synthetic lubricants Polyalkylene glycols (PAG) Polyalphaolefins (PAO) 302

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5. Materials MEDIA TO BE SEALED WITH INDICATION OF PERMANENT TEMPERATURE [°C] Mineral hydraulic fluids HLP according to DIN 51524 part 2 +100 HLVP according to DIN 51524 part 3 +100 +150 +150 +150 +150 +150 +150 +150 +150 +100 +100 Biodegradable hydraulic fluids HETG rapeseed oil ** HEES – synthetic esters HEPG polyglycols*** Fire resistant hydraulic fluids Group HFA*** Group HFB*** Group HFC*** Group HFD **** Other media      – – + + +   – + + +   – + + +   – +150 +150 +150 + + + + + +150 +150      – – – –   – –   – –   +100 +90 +   –   – – – I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B Heating oil EL and L +90 Brake fluid DOT 3/DOT 4 Water*** Suds*** Air +100 +200 +200 +200 +200 +120 The values given are based on a limited number of tests on standard test specimens (2 mm sample plates) from laboratory production. The data determined from finished parts may deviate from the above values depending on the manufacturing process and the part geometry. The low temperature limit depends on the shaft run-out. 1) When using FKM materials in synthetic lubricants polyalkylene glycols (PAG) and polyalphaolefins (PAO), the max- imum operating temperature must be determined by a test or hydraulic power unit run. ** Application limits specified by the fluid *** Additional lubrication recommended **** Resistance depends on HFD type resistant, generally not used for these media +  conditionally resistant – not resistant  on request S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 303 X E D N I

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Seals for Rotary Applications 5.2 SPECIAL MATERIALS FOR SIMMERRING® MATERIAL CLASSIFICATION ACC. TO ASTM D2000 HARDNESS (SHORE A) COLOR APPLICATION EXAMPLES 70 NBR 110558 M2 BG 710 70 NBR 260866 M2 BG 710 75 FKM 170055 M7 BG 814 82 NBR 132919 M6 BG 814 70 FKM 260737 M7 BG 814 75 FKM 106200 M2 BG 71 80 NBR 94207 M7 BG 810 90 NBR 129208 M7 BG 910 75 HNBR 260258 M2 BG 714 80 HNBR 172267 M7 BG 814 70 70 75 80 70 75 80 90 75 80 Black Black Washing machines Washing machines Dark brown Drive technology e.g. PG oils Blue Low temperature applications Black Low temperature applications Black Black Seawater/ship waves Black Special pressure applications Black Special pressure applications, power steering systems MATERIAL 70 NBR 110558 70 NBR 260866 75 FKM 170055 82 NBR 132919 70 FKM 260737 75 NBR 106200 80 NBR 94207 90 NBR 129208 75 HNBR 260258 80 HNBR 172267 MEDIA TO BE SEALED WITH INDICATION OF PERMANENT TEMPERATURE [°C] ASTM D 2000 M2 BG 710 M2 BG 710 M7 BG 814 M6 BG 814 M7 BG 814 M2 BG 710 M7 BG 810 M7 BG 910 M2 BG 714 M7 BG 814 Permissible low temperature Mineral lubricants –30 –30 –30 –40 –30 –40 –25 –30 –30 –30 Engine oils +100 +100 150+ +100 +150 +100 +100 +100 +120 +120 +100 +100 +150 +100 +150 +100 +100 +100 +120 +120 +80 +80 +140 +80 +140 +80 +80 +80 +100 +100 +100 +100 +150 +100 +150 +100 +100 +100 +120 +120 +100 +100 +150 +100 +150 +100 +100 +100 +120 +120 Gear oils Hypoid gear oils ATF oils Greases 304

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5. Materials MATERIAL 70 NBR 110558 70 NBR 260866 75 FKM 170055 82 NBR 132919 70 FKM 260737 75 NBR 106200 80 NBR 94207 90 NBR 129208 75 HNBR 260258 80 HNBR 172267 MEDIA TO BE SEALED WITH INDICATION OF PERMANENT TEMPERATURE [°C] Synthetic lubricants Polyalkylene glycols (PAG) Polyalpha- olefins (PAO) 1) 1) 1) 1) 1) 1) 1) 1) 1) 1) 1) 1) 1) 1) 1) 1) 1) 1) 1) 1) Mineral hydraulic fluids HLP acc. to DIN 51524 part 2 HLVP acc. to DIN 51524 part 3 +100 +100 +150 +100 +150 +100 +100 +100 +100 +100 +100 +100 +150 +100 +150 +100 +100 +100 +100 +100 Biodegradable hydraulic fluids HETG rapeseed oil**  HEES – synthetic esters  HEPG polyglycols***  Fire resistant hydraulic fluids    – Group HFA*** Group HFB*** Group HFC*** Group HFD **** Other media Heating oil EL and L Brake fluid DOT 3/DOT 4 +90 +90 – – Water*** +90 +90       – + + +   – +150 + –       – –  –  + + +   – +150 + –       – –      – –      – – +90 +90 +90 –  –  –       – –  –       – –  –  I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 305 X E D N I

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Seals for Rotary Applications 5.2 SPECIAL MATERIALS FOR SIMMERRING® MATERIAL 70 NBR 110558 70 NBR 260866 75 FKM 170055 82 NBR 132919 70 FKM 260737 75 NBR 106200 80 NBR 94207 90 NBR 129208 75 HNBR 260258 80 HNBR 172267 MEDIA TO BE SEALED WITH INDICATION OF PERMANENT TEMPERATURE [°C] Suds*** Air +90 +90         +100 +100 +200 +100 +200 +120 +100 +100 +130 +130 1) When using FKM materials in synthetic lubricants polyalkylene glycols (PAG) and polyalphaolefins (PAO), the max- imum operating temperature must be determined by a test or hydraulic power unit run. ** Application limits specified by the fluid *** Additional lubrication recommended **** Resistance depends on HFD type resistant, generally not used for these media conditionally resistant + ⊗ – not resistant  on request 5.3 MATERIALS FOR HEAVY INDUSTRY MATERIALS 7 6 1 V U A 3 9 7 9 2 B R B N 0 6 1 0 5 0 1 R B N 0 7 5 6 5 5 4 2 R B N 0 8 1 4 2 B R B N 0 8 1 6 4 5 4 2 R B N 5 8 3 0 2 B R B N 5 8 7 4 2 B R B N 5 8 8 4 2 B R B N 5 8 7 6 4 U R B N H 5 7 0 4 0 0 1 R B N H 5 8 8 9 6 K M K F 5 6 0 7 6 K M K F 0 7 2 6 6 5 4 2 M K F 5 8 3 8 6 K M K F 0 9 2 4 1 V U A 5 9 MEDIA TO BE SEALED WITH INDICATION OF PERMANENT TEMPERATURE [°C] ASTM D 2000 – –       M2 BG 910        Permissible low temperature –30 –20 –40 –20 –30 –30 –25 –30 –20 –20 –20 –20 –20 –10 –20 –20 Mineral lubricants Engine oils Gear oils Hypoid gear oils ATF oils Greases + + + + +100 +100 +100 +100 +100 +100 +100 +100 +120 +120 +150 +150 +150 +150 +100 +100 +100 +100 +100 +100 +100 +100 +120 +120 +130 +130 +150 +130   +80 +80 +80 +80 +80 +80 +80 +80 +100 +100 +130 +130 +150 +130 + + +100 +100 +100 +100 +100 +100 +100 +100 +120 +120 +130 +130 +150 +130 +110 +110 +100 +100 +100 +100 +100 +100 +100 +100 +120 +120 +130 +130 +130 +130 Synthetic lubricants   +80 +80 +80 +80 +80 +80 +80 +80 +120 +120 +130 +130 +130 +130   +80 +80 +80 +80 +80 +80 +80 +80 +120 +120 +130 +130 +130 +130 Polyalkylene- clycols (PAG) Polyalphaole- fins (PAO) 306

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5. Materials 7 6 1 V U A 3 9 7 9 2 B R B N 0 6 1 0 5 0 1 R B N 0 7 5 6 5 5 4 2 R B N 0 8 1 4 2 B R B N 0 8 1 6 4 5 4 2 R B N 5 8 3 0 2 B R B N 5 8 7 4 2 B R B N 5 8 8 4 2 B R B N 5 8 7 6 4 U R B N H 5 7 0 4 0 0 1 R B N H 5 8 8 9 6 K M K F 5 6 0 7 6 K M K F 0 7 2 6 6 5 4 2 M K F 5 8 3 8 6 K M K F 0 9 MATERIALS 2 4 1 V U A 5 9 MEDIA TO BE SEALED WITH INDICATION OF PERMANENT TEMPERATURE [°C] I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H Mineral hydraulic fluids HLP acc. to DIN 51524 part 2 HLVP acc. to DIN 51524 part 3 +110 +110 +100 +100 +100 +100 +100 +100 +100 +100 +120 +120 +130 +130 +130 +130 +110 +110 +100 +100 +100 +100 +100 +100 +100 +100 +120 +120 +130 +130 +130 +130 Biodegradable hydraulic fluids HETG rapeseed oil ** HEES – synthetic esters HEPG polyglycols*** +60 +70 +60 +60 +60 +60 +60 +60 +60 +60 +80 +80 +80 +80 +80 +80 +80 +90 +80 +80 +80 +80 +80 +80 +80 +80 +80 +80 +100 +100 +130 +100 +40 +60 +60 +60 +60 +60 +60 +60 +60 +60 +100 +100 +55 +55 +80 +55 Fire resistant hydraulic fluids Group HFA*** +50 +70 +55 +55 +55 +55 +55 +55 +55 +55 +55 +55 +60 +60 +60 +60 Group HFB*** +50 +70 +50 +50 +50 +50 +50 +50 +50 +50 +60 +60 +60 +60 +60 +60 Group HFC*** +40 +60 +60 +60 +60 +60 +60 +60 +60 +60 +60 +60 +60 +60 +60 +60 Group HFD ****  + – – – – – – – – – – +100 +100  +100 Other media Heating oil EL and L Brake fluid DOT 3/DOT 4 Water*** Suds*** Air   +80 +80 +80 +80 +80 +80 +80 +80 +80 +80 +100 +100 +100 +100 – – – – – – – – – – – – – – – – +40 +80 +100 +100 +100 +100 +100 +100 +100 +100 +120 +120 +120 +120 +120 +120 – – +60 +60 +60 +60 +60 +60 +60 +60 +100 +100     +110 +110 +100 +100 +100 +100 +100 +100 +100 +100 +130 +130 +200 +200 +200 +200 ** Application limits specified by the fluid *** Additional lubrication recommended **** Resistance depends on HFD type resistant, generally not used for these media conditionally resistant + ⊗ – not durable  on request R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 307 X E D N I

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Seals for Rotary Applications 5.4 MATERIALS FOR THE PROCESS INDUSTRY MATERIAL COLOR CROSSLINKING/ FILLER 4 0 0 2 / 5 3 9 1 ) C E ( . G E R 6 0 0 2 / 3 2 0 2 ) C E ( . G E R ) C E ( . G E R 1 1 0 2 / 0 1 70 EPDM 291 Black Peroxide 70 EPDM 335 Black Peroxide 70 NBR 438 Black Peroxide 75 Fluoroprene® XP 45 Blue Peroxide PTFE E202 Beige Ekonol PTFE G223 White Glass PTFE Y002 Beige Special PTFE G116 White Glass PTFE G224 Blue Special Quantum® PTFE F18245 Quantum® PTFE F53722 Brown Special White opaque Glass                       Y R A T I N A S A 3 S D R A D N A T S      E E R F I D A            1 5 F S N  A D F            ) I O V V N I ( 8 8 . H C I V S S A L C P S U R E T P A H C P S U ) O R T I V N I ( 7 8 / 6 0 8 4 B G 9 8 6 9 B G       The multitude of different applications in the food and beverage, pharmaceutical and chemical industries, such as fill- ing lines or mixers, place different demands on the right sealing solution. Radial shaft seals made of specially developed materials conform to the relevant industry-specific standards. Drive shafts in the process industry 308

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6. INFLUENCING FACTORS 6. Influencing factors The processes in the tribological system of the radial shaft seal are influenced by various operating and design parameters. These include, for example: y circumferential speed of the shaft y temperature y pressure The following section explains these para meters and their implications. Calculation of the circumferential speed “v” of the shaft according to the formula: v (m/s) = Shaft Ø D (mm) x Speed (1/min) x 60000 Permissible circumferential speeds accord- ing to DIN 3760 (→ Fig. 136). The values given are guide values. The prerequisites are sufficient lubrication and good heat dissipation. Under less favorable condi- tions, correspondingly lower values apply. 6.1 BOUNDARY CONDITIONS If several limit values of the permissible operating conditions coincide, e.g. y if the elastomer material is not correct- ly selected for the operating conditions y the max. permissible circumferential speed (→ Fig. 136) y the max. permissible temperature y the max. permissible pressurization y and especially with sparse lubrication or limited heat dissipation the application limits of the radial shaft seals will be reached and exceeded, and the service life will be limited. 6.2 CIRCUMFERENTIAL SPEEDS OF THE SHAFT The circumferential speed, formed from the speed and diameter of the shaft, is the determining influencing variable for determining the design and material of the radial shaft seals. Three ranges characterize the permissible circumferential speeds: y use of the material NBR y use of the material FKM y outside both ranges, the use of stand- ard Simmerring® is not possible. As soon as the operating point lies out- side the ranges for FKM and NBR, special designs are required. These must be requested individually via your contact person Important notes: The values taken from the diagram (→ Fig. 136) are based on an application with good lubricant supply using an SAE 20 en- gine oil with good lubricating and wet- ting properties. The values are therefore not transferable to lubricants with lower lubricating and wetting properties. If other lubricants are used, significantly different limit values can sometimes be expected in the limit range. When using a component with a dust lip with overlap to the shaft, the maximum circum ferential speed is 8 m/s (depending on the remain- ing operating conditions) → Special de- signs see page 122. Map-marker-edit Higher speeds possible by trim- ming or venting the dust lip I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 309 X E D N I

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Shaft speed [rpm] 30 000 15 000 10 000 9000 8000 7000 6000 5000 4500 4000 FKM 3500 ] s / m [ d e e p s t f a h S 3000 2500 2000 1500 1000 NBR Grease 500 200 ... 500 Seals for Rotary Applications Speed limit design Limit: see diagram No dust lip or trimmed dust lip without contact to the shaft vented dust lip with contact to the shaft ] s / m [ d e e p s l a i t f n e r e m u c r i C 40 30 20 10 Limit: 15 m/s Limit: 8 m/s Standard dust lip with contact to the shaft 5 0 0 25 50 100 150 Fig. 136 Guide values for the permissible circumferential speed for Simmerring® (guide values) made of the materials NBR (72 NBR 902) and FKM (75 FKM 585) with sealing of engine oil SAE 20 and sufficient lubricant supply (diagram is not applicable with lubricant supply by spray oil or oil mist due to low cooling - diagram not relevant for pressure seals) Shaft diameter [mm] 310

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6. Influencing factors As the pressure on the sealing lip increases, so does the overtemperature at the seal- ing edge. For guide values when using a solid shaft and good lubrication, please refer to → Fig. 139. The use of a Simmerring® with a dust lip overlapping the shaft surface results in excess temperatures of up to > 20 °C in the tribological system. Exceeding the permissible temperatures for the respective materials leads to: y heavy wear y early hardening of the sealing lip and y shortened service life 6.3 TEMPERATURE Due to the relative velocity between the sealing edge and the shaft surface and the resulting friction, the temperature at the sealing edge is always higher than in the oil sump. This overtemperature (temperature dif- ference between oil sump and contact temperature in the sealing gap between sealing edge and shaft surface) depends on the following parameters: y rotational speed or circumferential speed y heat dissipation (via the shaft and/or via fluid exchanged between oil sump and sealing gap) y shaft surface y contact pressure of the sealing lip on the shaft surface (influenced by housing overpressure, design of the seal, elas- tomer material and other parameters) y physical and chemical properties of the fluid to be sealed The fill level of the fluid to be sealed in the unit influences the heat dissipation and thus the temperature in the sealing gap. The range between the upper and lower limit curves (→ Fig. 137) shows the possi- ble influence on the excess temperature depending on the given heat dissipation: y lower limit curve for full shaft immersion y upper limit curve for 25% shaft recircu- lation The ranges given for the individual media are based on their different lubricity and heat conductivity. As the rotational speed or circumferential speed increases, the excess temperature at the sealing edge rises (→ Fig. 138). I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 311 X E D N I

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Seals for Rotary Applications ] C ° [ t e r u a r e p m e t r e v O 120 80 40 0 0 Grease Gear oil SAE 90 Engine oil SAE 20 40 80 120 160 Shaft diameter [mm] Fig. 137 Overtemperature at the sealing edge of a Simmerring® when sealing different media. Oil bath temperature +100 °C, speed 3,000 rpm ] C ° [ t e r u a r e p m e t r e v O 80 60 40 20 0 Speed 6.000 rpm 3.000 rpm 1.500 rpm 0 20 40 60 80 100 120 140 160 Shaft diameter [mm] Fig. 138 Overtemperature at the sealing edge of a Simmerring® as a function of speed. SAE 20 engine oil, oil bath temperature +100 °C, oil level: center of shaft ] C ° [ e r u t a r e p m e t r e v O 80 60 40 20 0 0 1.5 bar pressureless 20 40 60 80 100 120 140 160 Shaft diameter [mm] Fig. 139 Overtemperature at the sealing edge of a Simmerring® with unpressurized sealing and pressurization, SAE 20 engine oil, speed 3,000 rpm, oil level: center of shaft 312

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6. Influencing factors 6.4 TIGHTNESS AT LOW TEMPERATURES Elastomers lose elasticity with decreasing temperature until they reach the glass state. Depending on the material, the glass transition temperature is between ‒10 and ‒40 °C. The freezing process is reversible, i.e., the material returns to its original properties with increasing tem- perature. In the case of rotary seals, heat is gener- ated by the friction occurring during movement. At temperatures at which there is already a risk of hardening due to freezing, the frictional heat can be suffi- cient to keep the seal elastic or to bring it into a functional state quickly enough after the start of movement. Due to the generally high viscosity of the lubricant, leakage at low temperatures is very rare in practice. Exceptions occur with very high shaft deflections and with fluids that have a low viscosity even at low temperatures (e.g. fuels). 6.5 ATEX APPLICATIONS y the ATEX Directive 2014/34/EU came into force on April 20th 2016 y the ATEX Directive applies to the design of electrical, explosion-protected equipment, devices and protective systems for intended use in explosion- protected areas Hot surfaces (EN 1127-1) Among other things, it is described that ignition can occur in explosive atmos- pheres if hot surfaces (e.g. shafts) come into contact with them. Depending on the circumferential speed, standard Simmer- ring® with a tarnishing dust lip can reach shaft surface temperatures of > +120 °C for a short time. Please contact the Freudenberg Sealing Technologies repre- sentative responsible for you. 6.6 PRESSURE As the pressure increases, so does the pressure on the sealing lip and conse- quently the disturbance of the hydrody- namics under the sealing edge, as well as the friction and overheating at the sealing edge. The pressure load p and the circumferen- tial speed v determine the application lim- its of the seals (→ Fig. 144 and → Fig. 145, page 317). If the respective limit values are exceeded, premature wear, premature hardening of the sealing lip and shortened service life must be expected. Standard Simmerring® are mainly designed for pressureless oper- ation or for use at very low pressures. Maximum pressure load: 0.02 to 0.05 MPa (→ Tab. 16). If the unit becomes so warm during operation that the enclosed air becomes pressurized, the installation of a vent valve is recommended. For a limited range of these loads, the use of the standard BABSL design is recommended. The characteristic feature of this seal is a short, yet flexible sealing lip. This design reduces the increase in the contact pres- sure of the sealing lip and thus the friction power. I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 313 X E D N I

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Seals for Rotary Applications PRESSURE DIFFERENCE [bar] max. MAXIMUM PERMISSIBLE SPEEDS [rpm] 0.5 0.35 0.2 Up to 1000 Up to 2000 Up to 3000 Tab. 16 Maximum permissible shaft speeds when pressurized SHAFT AT CIRCUMFERENTIAL SPEED [m/s] max. 2.8 3.15 5.6 6.7 SEALING AGAINST DIRT For sealing against dirt, dust and moisture on the air side, the use of a Simmerring® with dust lip is recommended. At circumferential speeds > 8 m/s, care must be taken to ensure that the dust lip does not make contact with the shaft. Before installation, the space between the sealing lip and the dust lip must be filled approx. 40% with grease to lubricate the dust lip and prevent corrosion of the shaft. Another option for protecting the sealing point against external contamination is the VRM01 or VRM02 upstream element (→ Fig. 141). 314

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6. Influencing factors > 8 4 … 8 < 4 → Fig. 167, page 359 U ] s / m [ v d e e p s l a i t n e r e f m u c r i C I & N O T C U D O R T N S E C I V R E S I D N A S L A I R E T A M S S E C O R P I G N R E E N G N E I R O F S L A E S Y R A T O R S N O I T A C I L P P A R E W O P D U L F I – S N O T A C I I L P P A S C I L U A R D Y H R E W O P D U L F I – S N O T A C I I L P P A S C I T A M U E N P weak medium strong (fordable) Friction contacts Grease filling Fig. 140 Simmerring® for reliable dirt sealing Dirt accumulation on air side S L A E S C I T A T S G N I L A E S L A I C E P S S T C U D O R P C I L U A R D Y H S R O T A L U M U C C A S W O L L E B & S T O O B BAUMSL in combination with VRM 01 VRM 01 starting on housing with BAUMSL VRM 02 starting on housing with BAUMSL Fig. 141 Simmerring® in combination with upstream element S M G A R H P A D I X O B G N I F F U T S I S G N K C A P 315 X E D N I

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Seals for Rotary Applications 7. SPECIAL DESIGNS Map-marker-edit Back-up ring drawing available Play-circle  Application example BABSL/PPS In addition to the standard BAUM/ BAUMSL design, other design and material versions are available for additional areas of appli- cation. 7.1 DESIGNS FOR PRESSURE APPLICATIONS USE/APPLICATIONS For pressurization > 0.5 bar, the catalog range includes the BABSL and PPS de- signs. Special customer-specific designs are available for higher pressure loads (→ Fig. 143). If no Simmerring® BABSL is available, the sealing lip can be supported by a back-up ring in the case of designs without a dust lip. Pressure p The back-up ring, which must be made of metal, must be precisely adapted to the sealing lip profile (→ Fig. 142). For this purpose, you can request a support ring drawing from your technical contact at Freudenberg Sealing Technologies. Pre- cise specification of the design is required. For higher pressure/velocity loads, special shapes with a higher but narrower func- tional range are used in the p-v diagram (→ Fig. 145). PPS DESIGN Further development of the proven BABSL design has boosted the performance range by up to 25%. The Simmerring® PPS (Premi- um Pressure Seal) has a patented sealing edge design that keeps the lip profile sta- ble up to twice the pressure load level of conventional designs. The dust lip provides protection against dirt entry and other con- taminants, preventing damage to the sealing edge. The specially developed sealing edge design makes the PPS ex- tremely suitable for high velocity (up to 15 m/s) and medium pressure (up to 40 m*bar/s) applications. Fig. 143 Installation of a Simmerring® with back-up ring BABSL PPS BAHDSN BAHDOF Fig. 142 Designs for pressurizable Simmerring® 316

Technical Manual 2025

Table of Contents

Services

Table of Contents

Materials and Process Engineering

Table of Contents

Seals for Rotary Applications

Table of Contents

Seals for Fluid Power Applications – Hydraulics

Table of Contents

Seals for Fluid Power Applications – Pneumatics

Table of Contents

Static Seals

Table of Contents

Special Sealing Products

Table of Contents

Hydraulic Accumulators

Table of Contents

Boots & Bellows

Table of Contents

Diaphragms

Table of Contents

Stuffing Box Packings

Table of Contents

Index