SMC Cargo Box Makes Its Debut.

It took 14 years to arrive, but the first all-composite rear cargo box became a commercial reality last month. Just now appearing in dealer showrooms is the 2001 Ford Explorer Sport Trac, a sport utility vehicle with an open rear cargo area like a pickup truck. Its one-piece SMC cargo box replaces around 20 metal parts and weighs 20% less than steel. According to Pete Miskech, technical specialist at Ford Body Structure Systems Technology in Dearborn, Mich., the SMC concept was proven in a demonstration project back in 1986. Then it sat on the shelf until Ford came up with a vehicle that required tooling up a new cargo box from scratch. At the planned volume of 65,000 units, an SMC mold costs one-fifth as much as tooling for a stamped sheet-metal assembly.

The cargo box consists of vinyl ester resin with 50% random glass fiber and 27% filler. A special glass was designed by Owens Corning of Toledo, Ohio. It provides fast wetout at the high line speeds used to make the SMC at the Van Wert, Ohio, plant of The Budd Co.'s Plastics Div.

The cargo box, which weighs close to 71 lb and measures about 51 x 51 x 19 in., is molded at Budd's North Baltimore, Ohio, plant. It is compression molded in a 2500-ton press with a robotic charge loader and parts unloader. Molding cycle is 140 sec, which Budd aims to get down to 110-120 sec. Total cycle is 220 sec, but the goal is 180 sec. The box is molded with a grained texture and needs no plastic inner liner. The SMC is pigmented black and later pained the same color. Ribs are molded into the underside of the box, so no supporting cross-members are required.

The second commercial plastic cargo box will appear this fall on a GM Chevrolet Silverado 1500 series full-size pickup truck. It will be molded of glass/urethane SRIM and surrounded by mica/polyurea RRIM fenders. Owens corning predicts that cargo and pickup boxes will consume 110 million lb/yr of composites by 2004.