DETROIT — Sometimes, a touch of adversity can become a prelude to a breakthrough.
A case in point is the a new I-section rear bumper beam on Mitsubishi Motor Corp.'s 1999 Galant sedan. That plastic composite part, which won the grand prize from the Society of Plastics Engineers Automotive Division annual awards, was not a foregone conclusion for the automaker.
Mitsubishi, which bases its U.S. operations in Normal, Ill., had planned to revert from plastic to roll-formed steel on its redesigned 1999 Galant model because of part costs, said Toshikazu Nojima, president of Mitsubishi R&D of America Inc. The plastic beams could not withstand the same impact as steel at a similar piece price, he said.
``We had a lot of discussion,'' Nojima said. ``In the beginning, steel was going to be used [on the Galant]. We liked its impact strength and cost.''
That would have meant lost business for CSP, a compression molder in Petoskey, Mich., also known as Continental Structural Plastics.
CSP compression molds the beams — the structural piece underneath a bumper's skin — for Mitsubishi's U.S. models at its 100,000-square-foot plant in northern Michigan.
To prevent that business from moving to steel, the firm started designing a new plastic rear beam four years ago. The beam was targeted to meet Mitsubishi's stringent goals: lowering costs, allowing design flexibility and providing ample strength to pass 5-mile-per-hour pole-impact tests.
Previous beams molded by CSP had used a C-shaped construction instead of the I-shaped beam seen on steel bumpers. Transferring that shape to a plastic part became a priority, said CSP Vice President Thomas Hilborn.
For Azdel Inc., a compounder of glass-filled polypropylene in Shelby, N.C., the situation was similar. Its Azdel front and rear beams, molded by CSP, were used on the Galant.
With steel making a comeback, Azdel had seen its share of the U.S. bumper-beam market slip from a high of about 16 percent in the early 1990s, said President Frank O'Neill of Azdel, a 50-50 joint venture of GE Plastics and PPG Industries Inc.
``That was enough of an incentive for us,'' O'Neill said. ``We wanted to come up with something new.''
What CSP and Azdel came up with was a beam never before used in the automotive industry: one with the appearance and performance of roll-formed steel, but about 20 percent cheaper.
The new beam integrates the two mounting stays that needed to be welded separately onto previous beams. The tabs slide into the vehicle's steel frame rail. Molding the part to the beam enhanced dimensional stability by keeping the stays from shifting location, Hilborn said. The part also needed fewer secondary operations, saving about $60,000 in equipment costs.
The beam system weighs 35-45 percent less than its steel counterpart, a fact not lost on a Japanese automaker. Japan places a high emphasis on fuel efficiency, low emissions and material reuse.
Azdel also cut 33 cents per pound by switching the raw material. The firm changed from a unidirectional fiberglass mat mixed with the PP resin to a chopped glass mat, or GMT, material, said Thomas Lewis Jr., Azdel's North American sales and development manager.
That first-ever plastic I-beam bumper may not be the only one. At least four other programs with major automakers are considering using the Azdel beam construction, O'Neill said.
And Mitsubishi plans to use the beams on its new Eclipse sedan due out in the United States in the year 2000, Nojima said. The company also is considering using the beams for several other models it produces, Nojima said
Mitsubishi plans to make about 60,000 Galant and Eclipse vehicles annually from its Illinois plant, Nojima said.
The automaker will move back to steel for its front bumper beams due to the material's greater ability to meet impact standards for a head-on collision, Nojima said. But advances in plastics could change that, he added.
CSP is happy with a small victory for plastic beams on the car's back end, Hilborn said. The use of the composite I-beams could spark future opportunities for plastic on car exteriors, he said.
``Now we have much work to do,'' Hilborn said.