Faster autoclave molding. (Composites).

The hood outer panel is molded and cured in an autoclave like typical aerospace composites. However, aerospace autoclave cycles often take 20 hr or more. For this special-edition run of 2000 to 3000 vehicles, Toray (known as TCA) formulated a prepreg that cures completely in only 10 min at 300 F. The P3831C prepreg consists of G83C quick-cure epoxy resin and Torayca T600SC standard-modulus carbon fiber. The hood is believed to be the highest production volume of a single carbon-fiber component using aerospace technology and is also the first use of Invar nickel/iron alloy tooling for an automotive production part.

Prior to molding, the prepreg is automatically cut into patterns and oriented in multiple directions to achieve balanced strength and stiffness. A significant challenge was the development of a mold release that allowed good paint adhesion without the need for scuff sanding or solvent wiping. Only GM's standard power wash is used. After autoclave molding, the skins are automatically routed and urethane adhesive is applied by a robot. Then the skins are bonded to the SMC inner panel and a primer is applied prior to shipping to GM's Bowling Green, Ky., assembly plant. There the hoods are handled just like standard SMC hoods.

Another recent breakthrough for large-scale automotive use of carbon-fiber composites was in the SMC fender brackets and supports and headlamp supports for the 2003 DaimlerChrysler Dodge Viper (see PT, Dec. '03, p. 52). However, these were not exterior appearance parts. TCA: [phone], www.torayusa.com/tca