Down To The Gram

Another thing is clear: The energy used to manufacture seals results in CO₂ emissions, unless the energy supply to the production plants has already been fully converted to sources that are neutral regarding greenhouse gas. “The great challenge is to correctly allocate the CO₂ emissions generated by energy that is supplied or created at a production site to individual material batches or products,” Schroiff explains. One prerequisite for this is knowledge backed up by measurements of how much energy is used in the individual process steps, specifically in relation to the weight, volume, or surface area. Based on the company’s core processes, a team at the Weinheim headquarters examined the specific energy consumption and other environmentally relevant parameters, such as the amount of technical or “engineered” waste consisting of partially or fully processed material. This kind of waste arises, for example, because products do not receive their final shape until they are finely machined in the production process. The four examined core processes include the mixing of the material, molding including vulcanization, coating, and reheating. In terms of material weight, the mixing proved to be similarly energy intensive as the molding and vulcanization. “But what surprised us in particular was that reheating consumes almost as much energy as the molding and vulcanization,” says Schroiff.

Sample products

In conclusion, the Freudenberg team transferred the results to two sample products, a Simmerring® made of fluoroelastomers (FKM) as used in the automotive industry and general mechanical engineering, and a housing part made of polyamide 6.6 with a functional coating for electromagnetic shielding. This revealed significant differences: For the Simmerring, the molding and vulcanization account for about half of the total production-related energy consumption. It is possible to reduce the CO₂ emissions by a third overall using an optimized molding process that does not require post-processing. For the housing part, the production of the plastic material accounts for a significantly higher proportion of around 40 percent of the energy input, while the coating accounts for about one-tenth. In the production of polyamide components, too, the material and possibly the technical waste account for a significant proportion of the total emissions.

Even if many materials and processes still need to be studied in more detail before transferring the methodology, a clear tendency is evident: “The greatest leverage for manufacturing components in a more climate-friendly way lies in avoiding waste during the production, at least as long as we are still using fossil energy,” Schroiff explains. Therefore, Freudenberg Sealing Technologies is resolutely focusing on waste-preventing production technology. By using cold runner injection molding with valve gate technology alone, the company already eliminates around 70 tons of waste per year and emits 600 tons less CO₂.