Japan's Mitsubishi Chemical Holdings Corp revealed that it is actively promoting "PCM" (prepreg compression molding) technology, which uses carbon fiber reinforced plastic (CFRP) to make large-sized parts, and Audi's The RS5 Coupe sports car roof is made using this technology.
The RS5 Coupe sports car roof is 60% and 30% lighter than a steel roof and an aluminum alloy roof, respectively. The PCM technology uses a pre-formed sheet material (made of carbon fiber impregnated with a thermosetting epoxy resin), which is heated with a mold and pressed into a carbon fiber reinforced plastic part.
By improving material composition and additives, Mitsubishi Chemical has developed an epoxy resin that hardens quickly and does not absorb water easily. As a result, the preform can be formed in three to five minutes, thereby shortening the processing time. Moreover, because of its low water absorption, it is less likely to become uneven during press molding, which helps improve its appearance.
In order to make a new roof, six to eight prepregs are stacked to make a multilayer prepreg, which is used as the roof material. In order to increase the roof strength, six to seven unidirectional prepregs are stacked as the angle changes, which makes the force even. A cloth prepreg made of woven carbon fiber is placed on the top layer of the roof to show the wrinkles of the carbon fiber.
The roof made of carbon fiber reinforced plastic is lighter and 60% lighter than the steel roof, so in addition to improving the appearance of the car, it can also reduce the center of gravity and improve driving performance.