DÜSSELDORF, GERMANY — Both Trexel Inc. (Hall 13/B46), with its MuCell microcellular foaming technology, and 3M (Hall 5/B10), with its glass beads, have proved they can reduce weight for plastic parts.
Now the two companies are working together to combine both systems and reduce the weight of injection molded parts by as much as 20 percent.
"It's as if for every five parts, one of them is free," said Charles Buehler, a General Motors Co. materials specialist who has experimented with using the combination of processes.
GM has been testing the potential for both glass beads and MuCell, using glass-filled poly¬propylene and glass-filled nylon. The nylon tests have used recycled nylon and virgin material. Engineers for the Detroit-based automaker have been testing parts in prototyping facilities at Proper Group International Inc. in Warren, Mich. The sites are set up to allow molders and their customers to test Trexel's processing.
Automakers including GM have approved parts for the past few years to reduce weight on their cars, which improves fuel performance. They are also now designing for MuCell from the start, rather than bringing the process in just before the start of production.
"We were looking at beads and we were looking at MuCell when we said, 'Let's put these babies together and see what happens,' " Buehler said.
On one part, the engineers could see an 8 percent reduction in weight by using MuCell alone, but up to double that with glass beads.
"Used alone, 3M glass bubbles or Trexel's MuCell can realize from 8-10 percent reduction in weight while maintaining mechanical and physical properties," said Doug Rowen, global business director for 3M glass bubbles. "Combined, the technologies complement each other, resulting in significantly increased weight reduction, cycle time reductions and improved dimensional stability of finished parts."
During testing, the systems together make it possible to improve part properties. Glass beads give the part strength, Buehler said, while MuCell helps the part retain impact performance.
Warp and sink is significantly reduced, while cycle time improves, reducing both scrap rates and production costs, he said. Molders can also use smaller presses with reduced clamping force requirements.
"It's challenging to take weight out of plastic parts without sacrificing strength, durability or function," said Steve Braig, president and CEO of Trexel.
"Through this innovative approach, customers can speed up the process and significantly reduce weight while maintaining the part integrity."
GM's testing looked at a variety of interior, exterior and functional parts, including an engine beauty cover, according to Buehler.
The carmaker has not established any material specifications at this time, but instead will be judging the potential for use in production parts through the ability to meet performance requirements.
"Typically everybody asks for the specs going forward, but we're going to be looking at the properties," he said.