New techniques cut cost of carbon fiber

Carbon fiber, once so costly that it was the preferred material only for fighter planes and supercars, is catching the attention of weight-conscious automakers.

Carbon fiber's cost is falling dramatically, thanks to production advances that let suppliers speed the material's finicky, and costly, curing process.

One technological breakthrough that makes carbon-fiber auto parts more affordable may come from a process used to make carbon-fiber golf clubs. More on that later.

While carbon fiber does not match steel or aluminum for cost, it is about 50 percent lighter than conventional steel and 30 percent lighter than aluminum. Its strength and weight make it ideal for electric cars, sports cars and luxury cars.

Consider these developments:

-- BMW AG's i3 electric car, which debuts in 2013, will have a carbon-fiber shell. BMW will build about 30,000 units a year.

-- General Motors may expand use of carbon fiber in the next-generation Chevrolet Corvette, which debuts as a 2014 model.

-- Daimler AG formed a joint venture with Japan's Toray Industries Inc. to make carbon-fiber components for the 2012 Mercedes-Benz SL.

-- A joint venture between Automobili Lamborghini S.p.A. and Boeing Co. has slashed the cost of carbon fiber used in a monocoque, or unibody construction, for the Sesto Elemento concept car. In effect, Lamborghini has become a carbon-fiber laboratory for its corporate parent, Volkswagen AG.

Under the skin

Carbon fiber is expensive in part because the production process is so labor-intensive.

About half of a carbon-fiber component's cost is due to the lengthy and finicky manufacturing process.

A worker places a carbon-fiber sheet on a mold, followed by a thin layer of resin, followed by another layer of carbon fiber.

Then the component is placed in an autoclave, a container that uses superheated steam under pressure, where it is carefully heated, then cooled. Using traditional techniques, it can take hours to make one part.

Now, automakers are finding ways to speed the process. Lamborghini and Callaway Golf Co. have partnered to develop a manufacturing process called "forged composites."

The new process, developed at the Advanced Composite Structures Laboratory at the University of Washington in Seattle, takes only three to five minutes to produce a part.

Forged composites don't require a traditional woven fabric. Instead, the carbon-fiber threads are cut into one- or two-inch pieces, mixed with resin and put into a heated mold under high pressure.

Callaway Golf uses the process to make golf club heads.

For automotive uses, the resulting part is slightly less strong than a carbon-fiber component produced with traditional techniques, but durable enough for most uses.

Forged composites are well suited for under-the-skin parts such as suspension parts and monocoques.

Lamborghini concept

The Lamborghini Sesto Elemento concept, which debuted last September at the Paris auto show, demonstrates the joint venture's forged composite technology.

The Elemento's monocoque body, front- and rear-end structures, suspension components, interior parts and exterior body panels are made of forged composites.

The Elemento weighs about 1,000 pounds less than a Lamborghini Gallardo. But the real lure for the auto industry may be the reduced cost of forged composites.

Forged composites are expected to be less costly than traditional carbon fiber by "orders of magnitude," says Paolo Feraboli.

Feraboli is an assistant professor of aerospace materials at the University of Washington and director of the Advanced Composite Structures Laboratory. The lab was opened in 2009 after Lamborghini made a $1 million donation.

On Sept. 30, Callaway Golf and Lamborghini announced their partnership to develop forged composites for various uses. Feraboli's lab has been conducting research for the partnership.

"In the next few years, you will see this material in a range of cars," he said. "And you will see this material in cars that you would never have thought could be carbon fiber."

By David Sedgwick- Automotive News