Automakers look under the hood for the next lightweighting opportunities

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General Motors Co. Plastic and composite parts on the powertrain of General Motors Co.'s Chevrolet Cruze.

TRAVERSE CITY, MICH. — The automotive industry’s current favorite target for lightweighting efforts is the powertrain, according to a recent survey.

The survey of 880 automotive insiders, from DuPont Co. and
WardsAuto, was released during the Center for Automotive Research’s Management Briefing Seminars in Traverse City.

Twenty-four percent of respondents said the engine and transmission are their primary targets for lightweighting, followed by chassis at 12 percent and body-in-white at 11 percent. Body panels tied with electrical and accessories at nine percent.

Jeff Sternberg, director of automotive technology at DuPont, speculates that successful weight reduction efforts in other structures of the vehicle are prompting a new focus under the hood.

“That’s where the opportunity is, right? Powertrain, engine, transmission — there’s just a huge amount of weight there. And, you know, go where the weight is when you’re looking for new opportunities. I think that’s one factor,” he said in a phone interview.

Sternberg also said he sees a growing understanding of and appreciation for how plastics and composites will function in a powertrain setting.

Materials engineers at General Motors Corp. discussed their attention to plastics’ performance in temperature- and chemical-intensive environments in a follow-up phone interview.

GM has already worked to convert many powertrain components to plastics or composites, including broad use in the engine of the Chevrolet Cruze, and uses of composite materials for acoustical treatments inside engine compartments.

General Motors Co. The Chevrolet Cruze

“We design around 150° [Celsius]; we need our plastics to function in that temperature environment,” said Derek Ewing, from GM’s transmission sector. “Also the plastic has to be resistant to the transmission fluid that it’s constantly exposed to, so chemical resistance and temperature resistance are properties that the plastic must have before we will convert the part to plastic from metal.”

Matt VanDyke, from the engine sector, said he looks to premium materials to provide the necessary properties.

“As power density goes up, temperature is on the rise under hoods, so for composite components on the engine, especially in sealing applications, we’re very conscious of temperature limits as well as limited creep that we would get out of using premium materials rather than everyday nylon,” he said. “We would investigate some of the higher-grade materials to keep the creep low, to have thermal expansion that would be closely matched to its mating component, to ensure that there’s no leaking of any sort of internal fluids.”

For now, the use of plastics isn’t being limited by high-pressure areas, although that could become more of an issue in the future, Matt added.

Ewing said he’s confident plastics and composites will continue to provide the properties needed to stand up in a growing number of under-the-hood applications.

“We are looking at different types of plastics right now, from nylons to PEEK to PPS, and all of these types of plastic materials have really good chemical resistance and temperature resistance,” he said. “Right now we’re working with our material manufacturers and they’re constantly developing better plastic materials as well. ... I see the opportunity for using plastics and developing plastics that will meet our performance requirements as continuous and ongoing and actually getting better, as opposed to reaching a plateau.”