Ford Motor Co. (Detroit, Mich.) on Oct. 9 displayed a prototype carbon fiber hood at the Composites Europe event in Düsseldorf, Germany. Developed in cooperation with the Hightech.NRW collaborative research project in Germany and Dow Automotive (Midland, Mich.), the prototype Ford Focus hood weighs at least 50 percent less than a standard steel version. As a result of progress made during an ongoing research project involving engineers from Ford’s European Research Centre (Aachen, Germany), the production time for an individual carbon fiber hood is reportedly fast enough to be employed on a production line — a significant step toward increased use of lightweight materials in Ford vehicles.
Inga Wehmeyer, advanced materials and processes research engineer at the Centre, says the hood comprises a sandwich construction, with carbon fiber faceskins and a foam core. The carbon fiber faceskins feature several plies of a unidirectional 24K tow carbon fiber fabric supplied by Toho Tenax (Wuppertal, Germany). Wehmeyer says the plies are stacked, tacked together with epoxy bonding powder, and then placed around Evonik’s (Marl, Germany) ROHACELL foam core. The resin is a thermoset provided by Henkel (Düsseldorf, Germany). The part is made via a refined gap-impregnation process, developed by IKV (Institute of Plastics Processing, at RWTH Aachen University). It works by injecting resin over a carbon fiber preform in a slightly open tool. The injection gate is located on one end of the mold cavity. As injection begins, the resin flows through and, importantly, over the preform in the small gap between the upper tool and the preform. During injection, the tool is gradually closed at a slight angle, compressing the preform on the end closest to the gate. As the tool angle closes, resin is forced into the remainder of the preform and, at the same time, forced throughout the remainder of the mold cavity. When the mold is fully closed, the compressed and fully wetout laminate is heat-cured.
Wehmeyer emphasizes that Ford is in the initial stages of development, relying to date exclusively on hand layup for prototype hoods manufactured at Composite Impulse GmbH (Gevelsberg, Germany). Initial results, however, are positive, and she says that over the next six months, Ford will begin low-volume production trials at IKV, targeting a total cycle time of 15 minutes, which she believes is achievable.
How soon consumers will see a carbon fiber hood on a production vehicle remains to be seen. Wehmeyer says Ford will evaluate material and manufacturing costs carefully. “At the end of the day, we have a customer and customer expectations, and price is certainly something we have to consider. Carbon fiber and its cost will be evaluated as we move forward with this project,” she says. “It’s no secret that reducing a vehicle’s weight can deliver major benefits for fuel consumption, but a process for fast and affordable production of carbon fiber automotive parts in large numbers has never been available. By partnering with materials experts through the Hightech.NRW research project, Ford is working to develop a solution that supports cost-efficient manufacturing of carbon fiber components.” The Hightech.NRW project began in 2010 and, although it has a charter through September 2013, it has already made significant progress toward its goals. But Wehmeyer warns, “Customers of Ford’s passenger cars should not expect to see carbon fiber-bodied examples on sale in the near future. The techniques we have refined and developed for the prototype Focus bonnet could be transferred to higher volume applications at a later date.”
The Ford European Research Centre’s involvement in the Hightech.NRW research project is a follow-on to Ford’s partnership with Dow Automotive, a collaboration announced earlier this year, to investigate new materials, design processes and manufacturing techniques. Dow and Ford say they intend to focus not only on developing high-volume molding methods but also on establishing an economical source of automotive-grade carbon fiber — both quests are considered critical to increasing the range of future Ford battery/electric and plug-in hybrid electric vehicles. Advanced materials, such as carbon fiber, are integral to Ford’s plans to reduce car weight, on average, by up to 748 lb/340 kg by the end of the decade.