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Carbon Composites Achieve Auto Breakthrough

Carbon Composites Achieve Auto Breakthrough

Plasan Carbon Composites is introducing a new production technology that dramatically speeds production of carbon-fiber reinforced plastics, the composite material used in the Boeing 787 Dreamliner. Until now, the material was not considered feasible for major automotive projects.

"This is a major breakthrough. Carbon fiber composites can now be used for medium-volume, base cars," Gary Lownsdale, engineering manager for the company, told Design News. Plasan has received significant production contracts to produce automotive parts at a new manufacturing plant under construction in the City of Walker, Mich. Two production lines are also being installed at a product development center in Wixom, Mich.

In the new process, 50,000 carbon composite vehicle sets can be built annually, up from 2,000 sets per year with current process technology. The big benefit is that carbon composites cut weight by 50 percent to 80 percent compared to steel. As a result, expect carbon composites to become a major player as auto manufacturers strive to meet tightening mileage requirements from the federal government. The Obama administration has set a 2025 fuel economy target for automakers at 54.5 miles per gallon.

Initial target applications for carbon composites in cars are hoods, roofs, deck lids, fenders, hatchbacks, doors, and air splitters. Down the road, look for carbon composites to replace steel in structural applications, such as underbodies. That research is already well underway by General Motors (GM), Ford, and Chrysler at USCAR.

Lownsdale says CFRP technology overcomes one of the major problems with plastic body panels found in early models of GM Saturns. Thermoplastic body panels on the Saturn grew and shrank when the temperature changed, requiring designed-in gaps around the doors, hood, and trunk for clearance. The problem was caused by a higher coefficient of linear thermal expansion (CLTE) for thermoplastics than steel. "There are no thermal expansion issues with carbon composites," he says.

Also, the new process produces a Class A surface finish that is described as comparable to steel.

Carbon composites made in autoclaves, the traditional manufacturing process, suffer cosmetic defects such as pitting. The surface finish is 80 percent better with the new, out-of-autoclave technology developed jointly by Plasan Carbon Composites and Globe Manufacturing, an equipment builder in Tacoma, Wash. In another big win, the panels can be painted in existing coating lines.

At the heart of the invention is a machine chamber that simulates what happens inside an autoclave. "We have synthesized heat pressure, temperature, and time in an autoclave and replicated them in an all-new piece of equipment." The equipment is called a "pressure press."

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. The build envelope in the current machine is six feet square. Lownsdale says the build envelope can be expanded for parts used in other markets such as aircraft and construction.

The new manufacturing plant in City of Walker is expected to be running at full tilt in two years.

Lownsdale says that more dramatic breakthroughs are coming: "Watch very closely for developments in thermoplastics." Thermoplastics are not cross-linked and do not require curing time. It takes thermoset epoxy, a primary composite matrix resin, about seven minutes to cure. The time it takes thermoplastics to harden inside a mold cavity depends on many factors, but it's easily three times faster than epoxy. Carbon fiber composites are typically made of 38 percent resin.

Plasan is an Israeli company that has developed world-leading composite technologies to make lightweight armor for tanks and other combat vehicles. Its products include the Add-On Armor Protection Kits for lightweight military tactical trucks for fixed- and rotary-wing aircraft and commercial vehicles. It entered the automotive composite business in the US with the acquisition of Vermont Composites, located in Bennington, Vt., in 2006.

TAGS: Aerospace
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