New production methods for seals in the hydrogen and electrolyzers sector

Are there new production methods for seals in the hydrogen and electrolyzers sector, Mr. Mähne?

Artur Mähne is Global Segment Manager, Hydrogen Technologies, at Freudenberg Sealing Technologies. He reports: “Yes – and this across the entire H2 value chain. In recent years, we industrialized several production-ready manufacturing process chains for electrolyzer stacks, peripherals, and H2 infrastructure. We specifically designed our manufacturing and testing processes for scalability, media purity, low permeation, and high-pressure capability. In essence, this involves modern extrusion lines, precision injection molding and overmolding onto carriers, as well as large-format press capacities – all backed by our material and process expertise. We develop and analyze all formulations, material properties, bonding behavior, and purity assessments for sealing solutions by applying the finite element method (FEA). I will gladly go into more detail and present our manufacturing processes in three sections.

I will start with a process for injection molding and overmolding of seals onto carriers (for bipolar plates and metal or thermoplastic frames)

At Freudenberg Sealing Technologies, we master the direct molding of seals onto metallic bipolar plates, metallic frames, and thermoplastic carriers. In these applications, key aspects include defined adhesion through bonding agents, controlled groove filling, and the geometric activation of the seal.

For PEM stacks, we have developed a seal design with high-pressure capability that has already been validated for series production. This consists of a groove clamp with retention properties: an L-shaped cross section that is “activated” under operating pressure into a C-shaped barrier. This design is usually injection-molded and demonstrates the interaction between geometry, bonding, and process. In H2 and electrolysis applications, the benefits include a lower number of components, a higher degree of automation, better reproducibility of the com pression position, and lower leakage and permeation.

Large-format presses for manufacturing XXL seals and large O-rings in all material classes

When it comes to large cell formats with diameters of 0.3–2 m and peripheral applications, we use powerful large presses to manufacture large-format frame seals, flat seals, and large O-rings – in line with the current scaling of electrolyzers toward MW/GW factories. Depending on the media window and bolt load, we produce molded EPDM and FKM elastomer parts. Our press capacity enables series production in high quantities. For H2 electrolysis, we offer the benefit of scalable surface sealing for large cells and covers, as well as robust tolerance absorption compatible with serial stacking and gigafactory cycle times.

Extrusion including an LCM (liquid curing method) line, for manufacturing profile and frame seals

We have specifically expanded our profile extrusion technology for hydrogen applications. For example, we developed a new extrusion line based on continuous production technology for delicate cross sections. We have the ability to vulcanize materials in a molten salt bath with optimized heat transfer and without exposure to air. This has allowed us to broaden the range of materials and cross-linking systems for large seals used in hydrogen applications, with a specific focus on reliability and durability. At the same time, our optimal process control has enabled us to significantly reduce manufacturing tolerances. This technology toolkit can be adapted with different extruders in LCM (liquid curing method) set ups, making it possible for us to manufacture continuous stack profiles with tight tolerances, low creep tendency, and high chemical resistance. For alkaline electrolysis (AEL), we are producing extruded profiles for seals with diameters of up to 2m and well beyond. The fundamental advantage of these manufacturing processes for H2 electrolysis is that we can now manufacture large seals in optimized and customized high-performance materials with minimal tolerance variations and high precision. This is important for stack service lives of many tens of thousands of hours.

In closing, the bottom line is this: Yes, there are new manufacturing processes – and we are focusing on vertical integration and scaling. We are investing in standardization and global production capacities at our sites in Europe, China, and the United States. We are doing this with the goal of supplying H2 seals reliably, sustainably, and locally for local markets in high volumes. Thanks to our material and process expertise, the concepts and methods described here are ready for series production – from AEL/AEM to PEM, and from stacks to H2 infrastructure. This directly contributes to the safety, service life, and scalability of electrolyzers. At our company, one thing becomes clear every day: Material and process expertise are the “second half” of every innovation.

Experimental curiosity is accelerating the develop ment of forward-looking solutions, especially in the energy sector. This inventive spirit also fuels continu ous advancement in materials, manufacturing pro cesses and sealing solutions at Freudenberg Sealing Technologies. Because one thing is clear: Seals are the decisive factors that enable efficiency, safety, and predictable life cycle costs in hydrogen systems. They are the technology drivers that make it possible to achieve the targeted cost and scaling effects.

This white paper helps you stay up to date on sealing solutions for the hydrogen process chain. At the same time, we offer important insights into how innovative technologies can help you move toward climate neutrality. We would be pleased to continue developing this white paper together with you and look forward to your feedback.

Marcel Schreiner

Global Segment Director Energy und Projektleiter H2 at Freudenberg Sealing Technologies

Marcel.Schreiner@fst.com

Artur Mähne

Global Segment Manager, Hydrogen Technologies at Freudenberg Sealing Technologies

Artur.Maehne@fst.com