Tech Briefs
GM to offer composite pickup truck

General Motors announced that it will offer a pickup truck box made of advanced composite materials that they say will offer durability, worry-free cargo loading, low-maintenance cost, and freedom from dents and corrosion. Dr. Lawrence D. Burns, Vice President of GM R&D and Planning, said, "Pickup truck cargo boxes are subject to a great deal of wear and tear. They are often the body component most susceptible to corrosion over time. We are not talking about just a traditional steel box with an industrial strength bedliner. This is an entire unit made of durable composite materials."

The new 2.0-m (6.5-ft) fleetside box will be available as an option on the full-size Chevy Silverado pickup beginning in the autumn of 2000. GM will be the first manufacturer to offer a composite box on its full-size pickup trucks. The box's fenders and outer tailgate panel are made of reinforced reaction injection molded (RRIM) materials, chiefly polyurea with mica filler. The one-piece inner panel and the inside of the tailgate are formed by a structural reaction injection molding (SRIM) process and consist of a 50/50 mix of urethane and glass fiber. The interior of the box and tailgate are painted with a dark gray "spatter paint" that provides a tough, pebbly surface as well as protection from ultraviolet rays.

The use of advanced SRIM and RRIM composite materials reduces the total weight of the truck by approximately 22.7 kg (50 lb), which improves fuel economy and payload carrying capability. The tailgate alone is roughly 6.8 kg (15 lb) lighter than a current steel tailgate, making it easier to open and close.

GM engineers installed 48 of the units on Chevy C/K pickup trucks and used them in phosphate and sulfur mines, chemical environments, and tar sand fields. The composite boxes were pounded, twisted, and punished for two years and 1.9 million km (1.2 million miles) at extreme temperatures ranging from -40° to +76.7°C (-40° to +170°F). The outer panels withstood denting and proved twice as damage resistant as composite outer panels used on such cars as the Chevrolet Corvette and Camaro, and the Pontiac Firebird. If a fender is damaged, it can be removed in less than 10 minutes, repaired in a matter of hours, and re-installed with a minimum of downtime. Most scratches on the inside of the box or tailgate can be polished out with a common commercial silicone cleanser.

The composite pickup box and tailgate are 100% recyclable and scrap from the manufacturing process will be reused to make other parts. Over the long term, GM says they are committed to developing the recycling infrastructure required to allow the composite box's various parts to be recycled.