Konzelmann TPU seals for e-mobility

Thermoplastic polyurethane (TPU) compounds which combine the properties of rubber and plastic are replacing traditional machined metal and rubber-metal seals.

One of the breakthroughs has been the development by German firm Konzelmann of a TPU material designed for sealing in hydrogen applications. The company has a dedicated sealings business unit focused on TPU material development and production.

Automotive Industries (AI) spoke to Milko Konzelmann, CEO of Konzelmann, and Heiko Kurz, Head of Sealing Technology Business Unit at Konzelmann, at The Battery Show Europe.

AI: What are the main advantages that plastic injection molding brings to automotive sealing technology compared to traditional materials?

Kurz: The injection molding process of our TPU, a thermoplastic elastomer, offers outstanding advantages over seals that are machined or made by compression molding. They include high degrees of complexity, short cycle times, and the ability to produce complex geometries.

AI: How does Konzelmann’s expertise in sealing technology contribute to vehicle weight reduction and performance optimization?

Kurz: Thanks to our experience with complex sealing applications and the very robust TPU material, we can replace a complicated metal or rubber-metal sealing solution with a pure TPU solution in some places – and thus achieve a noticeable weight reduction while optimizing vehicle performance at the same time.

AI: Can you share how your customized solutions improve assembly processes for automotive manufacturers?

Kurz: Our customized TPU solutions allow for particularly easy-to-install geometries. For example, we have been able to replace very rigid PTFE seals with highly flexible TPU sealing solutions, which are much easier to fit into the installation space and noticeably reduce assembly work.

AI: How closely does your team work with OEMs and Tier 1 suppliers to develop tailored sealing components?

Konzelmann: Our development work goes hand in hand with the OEMs and Tier 1 suppliers. We achieve an excellent development flow by precisely adhering to the requirements in the specifications and checking the media resistance and specifications, which we report back to the customer in regular meetings.

Our engineers work intensively on the application in order to understand all the details and interrelationships and ultimately develop the perfect sealing solution.

AI: In what ways have technological advancements in plastic injection molding enabled new applications for Konzelmann in the automotive sector?

Kurz: Plastic injection molding, especially for our TPU seals, has hardly changed technologically in recent years.

We therefore do not see any technological progress in this area.

Instead, alternative drive concepts in the automotive industry are opening up new fields of application for our TPU seals.

In electric and fuel cell vehicles, the operating temperatures are well below the maximum continuous temperature of 110 °C for TPU. This means we can use TPU seals where they were previously out of the question due to thermal stress, thus establishing new sealing solutions in vehicle construction.

AI: What sustainability measures do Konzelmann implement in the development and production of its plastic sealing components?

Konzelmann: Our material development department has recently started using a high proportion of biogenic raw materials – such as castor oil – for the production of our high-performance TPUs.

This is done in close cooperation with our selected raw material suppliers and under constant validation and monitoring of the results in our chemical laboratory – our contribution to reducing CO₂ emissions.

At the same time, we have eliminated the use of banned substances or PFAS compounds.

AI: How does your approach to process optimization benefit both Konzelmann and your automotive clients?

Konzelmann: Our material development aims to achieve optimum processability: through prototype trials of our newly developed compounds and, where necessary, targeted recipe adjustments, we attain outstanding process stability.

Both we and our customers benefit, as tool cleaning intervals and cycle times are reduced – resulting in significant cost savings and an overall more efficient production.

AI: What are some of the challenges in developing durable and reliable plastic seals for modern vehicles, and how do you overcome them?

Kurz: Constantly changing demands in automotive applications pose significant challenges in development. While transmission or engine oils used to be the main media with which our seals came into contact, today it is water-glycol mixtures for battery cooling, battery acids or even extremely volatile hydrogen.

Hydrogen, in particular, presents significant challenges for the sealing community.

Pressures up to 1,050 bar, temperatures as low as -50 °C or even -60 °C, and its’ very high volatility demands new materials. Our response is a rigorous and uncompromising validation of both material and design requirements.

Konzelmann has developed purkon®2000, a brand-new material engineered to withstand these challenges – TÜV-certified.

AI: Looking ahead, what innovations or trends in sealing technology are you most excited about within the automotive industry?

Kurz: In sealing technology, one trend particularly excites us: fuel cell and hydrogen technology.

Although this technology is relatively mature and has so far “lagged behind”, we view it as a necessary complement to purely battery-powered vehicles. Consequently, in the automotive sector, our TPU seals are primarily focused on this technology.

About Konzelmann

For more than 60 years, Konzelmann has stood for innovations made of plastics. The family-run company is headquartered in Löchgau, Germany, and has an office in Detroit, USA, as well.

Konzelmann develops polymeric components and systems for friction optimization as well as emission reduction.

Its customers are major OEMs and Tier 1 suppliers in the automotive, medical and industrial sectors.

Konzelmann’s experts follow a holistic approach to finding solutions: through intensive listening and many years of expertise in the development of special technical applications, individual solutions with a holistic view of product and process interfaces are created in exchange with the customer. The result is reduced production costs with superior product properties.

Current examples are the KBerstring® developed in-house, which increases the safety of batteries in the course of e-mobility, purkon®2000 development for comprehensive leakage protection from electrolysis to fuel cells and the ID Sealing (REDI), which can significantly reduce both leakage and frictional torque.