Casting Study: Air Extractor Cover

In their original version, these parts were produced in glass fibre reinforced resin, 3-4.5 mm thick and containing two brass inserts to fix them to the car body. These components are painted on the body to match the rest of the car. Problems encountered during stoving the paint – distortion and blistering – led to a high proportion of retouching work. This led the carmaker to use zinc die castings. The zinc die cast parts – 1.2 mm thick – are much more rigid, which makes for better assembly with the steel sheet bodywork, and they do not distort during stoving. Thanks to new die casting technology, the parts are cast with excellent surface quality, and are free from porosity, so that they can be stoved at high temperatures without blistering. They are delivered with a chromated surface so that they can go directly to painting with no other preparation. The use of thin wall sections and elimination of the brass inserts have made the zinc die castings cost-effective, compared with the previous material.