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U.S. Department of Energy Energy Efficiency and Renewable Energy

DOE-Funded Research Leads to Manufacturing Technology Used in 2004 GM Production Vehicles

April 8, 2004

Photo of Chevrolet Malibu Maxx.

GM manufactures the rear liftgate of the new Chevrolet Malibu Maxx by using an aluminum-forming process first investigated with funding from DOE's FreedomCAR and Vehicle Technologies Program. Photo courtesy of GM.

General Motors manufactures the rear liftgate of one of its hottest new cars by using a production technique first investigated by the U.S. Department of Energy's (DOE's) Pacific Northwest National Laboratory (PNNL), General Motors (GM), and Kaiser Aluminum under a DOE-funded cooperative research and development agreement (CRADA) in the early 1990s.

The new process debuts this year in the production of the 2004 Chevrolet Malibu Maxx rear liftgate. Before implementing the new forming technique and material, GM anticipated that the Malibu Maxx liftgate would weigh almost 40 pounds. The final weight is nearly half that thanks to the new material and process, which is a major initial commercial exploitation of the metallurgical phenomenon of superplastic forming used for decades in aerospace applications.

Originally called "superplastic forming," the aluminum-forming process that has evolved into "quick plastic forming" permits production-volume manufacturing of complex-shaped body panels as one piece. In the past, such complex body panels were either restricted to use on low-volume specialty vehicles, or they were constructed with multiple parts and materials that added complexity and time to the manufacturing process, as well as weight to the finished vehicle.

When GM, PNNL, and Kaiser Aluminum first began working on the superplastic forming concept in 1992, the automotive industry still relied on traditional die-stamping for mass-produced body parts. That process could not create the kinds of complex body panel shapes manufacturers sought. The aerospace industry was using an aluminum-forming process known as superplastic forming, but it proved too slow and expensive for the automotive industry.

The PNNL-GM-Kaiser CRADA identified processing techniques for several new aluminum alloys that could be used to increase the speed of the superplastic forming, making it a more cost-effective manufacturing process. Following initial developments, GM went on to develop its proprietary quick plastic-forming process that can be used for high-volume, lighter weight, more fuel-efficient vehicles.