Momentive and Kromberg & Schubert Collaborate on Technology to Enable Light Weight Design for Automotive Battery Cables
Waterford, N.Y. (October 12, 2016) – Vehicle weight directly impacts the fuel economy and CO2 emission of combustion engines. Light weight design is therefore a significant developmental challenge for automotive engineers, especially for the structure of electrical vehicles.
One solution to lower vehicle weight is substituting copper automotive wiring with aluminum, which is lighter and cheaper and can therefore reduce both weight and cost. The use of aluminum, however, particularly in areas where it is connected to nobler metals, can lead to electrical-chemical corrosion in the presence of humidity.
To address this unique challenge, the German specialist for electrical cables Kromberg & Schubert has developed a new aluminum high-amp battery cable characterized by function and robust performance. In this application, the critical and sensitive connection between aluminum wire and the tin coated terminal is sealed by a self-bonding liquid silicone rubber (LSR) to protect the aluminum against humidity and avoid corrosion. The wire and clamp assembly is overmolded with Momentive Performance Materials' (Momentive) Silopren* LSR 2740 liquid silicone rubber by injection molding. The LSR builds up chemical bonding to both the metal and polymer components of the cable assembly. The bonding-performance of Silopren LSR 2740 liquid silicone rubber helps ensure reliable long-term sealing functionality while the assembly is exposed to changing temperature between -40 and + 150 °C, high humidity, fluids, vibration and mechanical stresses. The mechanical properties of Silopren LSR 2740 liquid silicone rubber stabilize and support the welded connection between wire and terminal and enable efficient injection molding in short cycle time.
"Our new concept for aluminum cables challenged know-how in material properties and manufacturing processes to provide the best function and performance under harsh environmental conditions," says Daniel Bechstein, Product Development and Component Manager, Kromberg & Schubert GmbH & Co. KG. "We contacted the specialists of our partners at a very early stage of the project to evaluate the most efficient solution for our idea. From the very early beginning, the cross-functional team of Rico and Momentive communicated clearly and openly and worked fast and pragmatically with our experts until successful ramp-up of the serial production. We are very happy about the fast market adoption of our innovative solution."
The concept of the application has been developed in close cooperation between Kromberg & Schubert, Rico Elastomere Projecting as a supplier of the manufacturing tools and Momentive, supporting the project with material tests and bonding trials to optimize performance and material selection.
Silopren LSR 2740 liquid silicone rubber is self-bonding with a hardness of 40 Shore A. Its excellent molding properties in combination with primerless adhesion to many plastic substrates, metals and even glass enables efficient hard-soft combinations without the use of additional adhesives or bonding agents in many applications for the Consumer and Automotive Industries.
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*Silopren is a trademark of Momentive Performance Materials Inc.