Tumble valve bearings in manifolds of next-gen V6 and V8 Mercedes Benz engines are reportedly the first to be made from an in-mold assembly process.
Schneegans GmbH in Germany used coinjection molding and two engineered resins to assemble the bearings inside the mold. The German car maker says this is significantly less expensive than traditional joining processes in terms of assembly, tooling, and machinery.
A high-performance polyamide 46 called Stanyl PA46 from DSM Engineering Plastics, is the first part in the assembly to be molded. It retains stiffness at high temperatures even close to its melting point so there’s no distortion as the second polyphenylene sulfide material injects around it. The key to in-mold assembly is that the PA46 and PPS don’t adhere to each other after cooling. During manifold operation, this ensures free movement of the bearing valve to optimize air flow in the combustion chamber and uniformly distribute the air/fuel mixture. The result is faster burning, more efficient combustion, and lower fuel consumption by up to 0.2 liters of gasoline per 100 km for the same engine power.