Major German chemicals producer BASF (Ludwigshafen; www.basf.com) has developed a flexible integral foam made from PU that can be used to produce lightweight engine covers. The cover is made from "Elastofoam" I 4603 and manufactured by Austrian firm Polytec Car Styling (Hörsching; www.polytec-group.com). BASF said important factors were that the cover was light, showed good acoustic damping properties and had a high quality surface.

Christian Schobesberger, responsible for technical development at Polytec, said: “Together with BASF, we have developed the part in such a way that material, production and functionality are optimally adjusted to one another. Moreover, we have achieved this in an unbelievably small amount of time. We can thus manufacture various geometries for different engine models and still simplify our logistics.”

Swedish car maker Volvo (Hisingen; www.volvo.com) is currently using the cover in four different petrol-engine models. The cover weighs about 1.3-1.7 kg, depending on the model.

In contrast to conventional engine covers made of two materials, the flexible soft cover is foamed in a one-shot process – one material in one process step – thus integrating acoustic and mechanical properties in one part. This saves process steps during production and the single component also allows better use of the space available around the engine.

The part has an open-cell foam structure on the bottom surface, which means it can absorb a lot of energy, resulting in increased passive safety for pedestrians in the event of an impact. BASF said the sound-absorbing material for the flexible, visible part has a low component density of 140kg/m³, is dimensionally stable, media resistant as well as resistant to thermal aging up to 150°C.