Quick Plastic Forming Makes Vehicle's Lift Gate Lighter

GM's aluminum process, referred to as quick plastic forming (QPF), enables the company to make more complex forms for production models, shapes previously limited to concept and low-volume niche vehicles.

The QPF process was developed for automotive applications and is adapted from a hot blow forming aluminum process used in the aerospace industry. The process, launched last year at GM's Metal Fabricating Center in New Hudson, Mich., is being used to create the panels for the Malibu Maxx lift gate.

"QPF provides GM greater flexibility to create body panels with eye-catching shapes and adds to our stable of technologies available to improve fuel economy," said Larry Burns, GM vice president of Research and Development and Planning.

By using QPF, GM is able to make the entire outer panel for the lift gate as one piece instead of two pieces, one steel and one plastic part, which would later need to be joined together.

"We are able to make the entire outer and inner panels for the Malibu Maxx deck lid, without any compromises, exactly as the designer intended," said Greg Bellopatrick, vehicle chief engineer for mid-size vehicles. "Color and fit are not an issue because the panels are one piece instead of several pieces, and they are painted in the assembly plant. Quality is enhanced because the part is more stable, and the assembly process is simplified."

Total mass of the lift gate was also cut nearly in half, from 39 pounds to 20 pounds.

In the traditional stamping process, sheet metal is deformed between two dies in a heavy press, causing the metal to conform to the shape of the dies. Because aluminum is less rigid than steel, aluminum stampings are particularly prone to springing back to their original shape.

With QPF, a heated aluminum sheet is subjected to high-pressure air that makes it conform to the shape of a hot tool. The high temperature improves the formability so that even complex shapes can be manufactured. Dimensionally correct panels are possible because "spring back" is nearly eliminated. The QPF process is math-based, with the dies created directly from design data. Simpler, one-sided tooling also reduces development time and aids in shortening the vehicle development process.

GM's QPF is the result of years of innovative research and development. GM holds an extensive intellectual property portfolio related to this technology, including more than 40 issued and pending patents.

General Motors Corp. (NYSE: GM), the world's largest vehicle manufacturer, employs about 325,000 people globally. Founded in 1908, GM has been the global automotive sales leader since 1931. GM today has manufacturing operations in 32 countries and its vehicles are sold in 192 countries. In 2003, GM sold nearly 8.6 million cars and trucks, about 15 percent of the global vehicle market. GM's global headquarters are at the GM Renaissance Center in Detroit. More information on GM and its products can be found on the company's corporate website at www.gm.com .

More about the research that resulted in QPF can be found at the U.S. Department of Energy's web site: http://www.eere.energy.gov/vehiclesandfuels/pdfs/success/super_plastic.pdf