Several technology developments point to the increased use of carbon composites in production cars in the near future. They may come on stream just in time to help automakers meet toughening federal mileage requirements.
Teijin, a Japanese fiber producer, has invented a carbon-fiber-reinforced plastic (CFRP) compression molding technology that targets metal replacement in large structural body-in-white components. Body-in-white refers to the stage in manufacturing in which a car body's sheet metal components have been assembled. Molding times for CFRP, also called carbon composites, have been cut to less than 60 seconds, compared to five minutes in traditional processes. Faster cycle times are achieved partially through the use of thermoplastic resins, which don't require curing time.
Plasan Carbon Composites of Bennington, Vt., says it has also achieved a production breakthrough and will install its new technology in a manufacturing plant being built in Walker, Mich.
"We have synthesized the pressure, temperature, and time in an autoclave and replicated them in an all-new piece of equipment," Gary Lownsdale, engineering manager for Plasan, told Design News. Parts are made in a 17-minute (or less) complete cycle that includes cure time and other factors. That's a 75 percent improvement over the autoclave process. "Some companies are talking about a one- or two-minute cycle, but that's not the full, balanced cycle I'm referring to."
The build envelope in the current machine is six feet square. Lownsdale says that envelope can be expanded for parts used in other markets, such as aircraft and construction.
In another important development, the US Patent Office awarded a patent for the concept of a composite automotive floor pan to the US Council for Automotive Research LLC (USCAR), a collaborative automotive technology organization formed by Chrysler, Ford, and General Motors. The project is focusing on using glass-reinforced plastic composites, but it could easily shift to carbon composites if their economics improve.
"If structural composite panels can move into production, one molded fabric SMC [sheet molding compound] floor panel could replace up to 17 steel parts and shed up to 25 pounds from the weight of a typical passenger car," Libby Berger, project chairman and staff researcher in General Motors' Chemical Sciences and Materials Systems Lab, says in an interview. "This patent is among the many great milestones of this project."
Fourteen companies have formed a consortium at the Oak Ridge National Laboratory to further the research and development of carbon fiber. Its members include DuPont, 3M, Plasan, and Dow Chemical. A new research and development plant is being built with a $35 million Department of Energy grant.