Composites are appearing more and more to be the hottest material in the automotive industry.

The latest forecast by the Automotive Composites Alliance predicts composites use will rise by 34% from 350 million lbs. in 2001 to 467 million lbs. by 2004. That outpaces the 7% annual growth rate expected for aluminum, a material often in the spotlight because of its high profile battle with steel.

“The use of thermoset composites by automakers has nearly doubled in the last decade, largely because composites have increasingly been chosen by automakers to replace steel for body panels and structural components,” says Mike Dorney, ACA chairman and vice president of sales and marketing for The Budd Co.'s Plastics Div.

The significant growth is largely due to composites finally being used for pickup box applications. But composites are expected to make serious gains in other automotive uses, including hoods, decklids and fenders. Driving demand is the trend toward differentiating vehicles, more lightweight components to improve fuel economy and better dent- and corrosion resistance. Pickup boxes are a prime example. A composite pickup box is about 70 lbs. (32 kg) lighter than a steel cargo box, is more durable and allows for unique designs such as storage compartments along the walls and one-piece contoured flare sides.

The future of composites is promising. But challenges remain. Composites often can't match steel and aluminum in appearance, especially reflection clarity, with the technologies currently being used. General Motors Corp. is facing this problem with its Pro-Tec composite pickup box technology. The automaker several times has delayed the debut of an industry-first fullsize composite pickup box on its fleet-size Chevy Silverado because of a surface anomaly on the fenders known as “wavy” which is exposed in quality tests by shining a fluorescent light against the composite part. “It's mainly a process issue,” explains a GM spokesman. “We're seeing a certain level of variation in our processes. We're working to smooth that out so the variation is reduced to acceptable levels.”

GM hopes to have Pro-Tec in production by summertime, almost a year later than planned. Despite the setbacks, GM says it remains committed to the project. And it apparently hasn't discouraged Toyota Motor Corp., Nissan Motor Co. Ltd. and DaimlerChrysler Corp. either; the three automakers are said to working on composite pickup programs.