Detroit’s Big Three love to show off advanced plastics in concept cars, but when the rubber hits the road they are favoring lighter and thinner metals as a fundamental weight reduction strategy. I’ve had the privilege in the last two weeks to interview the top materials engineers at GM, Ford and Chrysler for an upcoming feature story on vehicle light weighting. Development of electric cars is ramping up light weighting efforts so that battery sizes can be minimized. As a result, the autos OEMs are willing to consider higher materials costs than might normally be the case.
One example: polycarbonate was used to make the roof module on the Chevy Volt concept car last year. PC is lighter than steel, and offers improved styling. Yet GM and Ford both have serious technical issues with the material for that application. “Its durability and robustness over time is the question,” comments Mark Verbrugge, the director of GM’s Materials and Process lab. “We’d very much like to use it. We’ve wanted to for years, but we haven’t been able to resolve all of the problems that have come up in our validation programs.” Shawn Morgans, Ford’s body structure technical leader, comments: “It’s (PC for roof modules) something we’ve looked at quite a bit, but it’s another technology that just isn’t ready for prime time. We’re finding some limitations to the material.” Those include weathering and scratch resistance.
The Detroit Three are planning increased use of thinner, high-strength steels, thanks in part to new structural adhesive technology. They are also expanding use of aluminum and magnesium.