By and large, plastics have been embraced in automotive for a vast array of non-structural applications. Check out an interior. Short of leather seats and the structure underlying the urethane foam (hmm. . .), most of the visible elements are likely to be plastic. Look at the instrument panel. It’s made of any number of plastics, including ABS (acrylonitrile-butadiene-styrene), polypropylene, and others. While that steering wheel may have a steel or magnesium core, it probably also makes use of vinyl or urethane (even if it’s wrapped with leather). There are the door trim panels of ABS or GMT composite (polypropylene/fiber glass). And much more. (Including that bad-looking “wood” that so many vehicle manufacturers seem to think means “luxury.”)
Under. Pop the hood. Intake manifold—plastic. Probably a nylon. Air cleaners are made with nylon and polypropylene. There are plastic (nylon or molded vinyl ester) rocker arms in some applicaitons. The oil pan can be made with the same. Plastic doesn’t rust, so is it surprising that water pumps are fabricated with nylon and polyphenylene sulfide (PPS)? Bearing housings are being made with nylon. Transmission seal rings: flouropolymers. Climb under the car and look at the polyetherimide oil pan. While you’re at it, note the high-density polyethylene (HDPE) blow-molded fuel tank (which is actually a multiplayer container—using more plastics). The fuel lines are nylon. And going back to the engine, there may be composite fuel rails (that are integrated with the nylon air intake manifold). Perhaps there’s even an entire sound-attenuating engine cover produced with nylon.
Outer. Meanwhile, on the outside, it is the same. The front and rear fascias are plastic, probably a TPO (thermoplastic olefin) or a polycarbonate or a poly- (ester/propylene/urethane/amide). Trim bits, from door handles to wheel covers: plastic. Nylons, polystyrene, and more. Headlamps have made the transition, largely, to polycarbonates, as have the various other lenses on the side and rear of the vehicle. There are lots of areas where plastic materials have come to the fore. Yet of the more obvious instances where there hasn’t been major ground gained is the body itself. Short of things like the polymer-paneled Saturns (which employ a GE Plastics PPO, a mineral filled Dow PC ABS, and a Montel TPO) and the composite-based Corvettes, there aren’t a whole lot of plastic-bodied vehicles. Steel remains supreme. And aluminum advocates are making an effort to gain more exterior real estate with some good effect (see “Aluminum Studies,” AD&P, May ‘03 ).
Reviewing applications such as these, Bruce Cundiff, a man who has been in the plastics industry for more than 35 years, and who is now the director of the American Plastics Council’s Automotive Learning Center (Troy, MI), admits that the change from an alternative material to plastic has largely been a matter of increments. Year after year, for about the past 20, he says, there have been changes, from some material for some application to a plastic material for that application. As he looks ahead: “The next five years, it won’t be much different. But in the next 20, then plastics are going to have a significant impact on what we’re going to see in cars.”
Structure. Part of this change, he believes, will come along with the transformations that are slowly taking place under the hood. Yes, he’s thinking about the changes that fuel-cell power could bring. But this isn’t so much a case of using plastic in the fuel cell (although the membrane technology to transform the fuel to electricity is going toward polymers). “There is a very efficient body architecture today for internal combustion engines,” he says. But he goes on to explain that the classic steel unibody architecture could certainly give way to a design that implements plastics for structural applications once that large internal combusion engine is replaced by a fuel cell. It just won’t be necessary to have the type of body structures that we now have (see “Creating the Chassis of Tomorrow,” AD&P, October ‘02 ).
But they’re not just waiting for fuel cells with regard to increased structural use. In fact, Cundiff says that plenty of work is underway by American Plastics Council member companies to develop predictive engineering tools and algorithms that will make computer-aided engineering (CAE) available for plastics in a way that’s analogous to steel. He admits that a current inhibitor to extensive structural application of plastics is the fact that it is, for example, “difficult to design and simulate crash.” The key is to be able to perform predictive engineering.
Did he say structural applications? Yes. In fact, he believes that there is the potential for architectures to be created that take advantage of the properties of plastics for structures. One comparatively recent example is the thermoplastic composite front-end module used for the Mini Cooper, which is both light and strong. Presumably, there are more applications that can be devised where plastics can replace what has historically been metal-centric.
Wilder. While there haven’t been a preponderance of new exterior panel applications, Cundiff says that with the new plastic film technology that’s been developed, there are some real potential opportunities for different types of exterior components to be made beyond, he notes, the film-coated fascia that’s used on the Dodge Neon. “This opens up new opportunities for designers and stylists,” he says, adding that beyond simple metallic colors that are currently employed, “There’s no reason why you couldn’t have plaid, or even a Jerry Garcia tie-dye.” For those who are more pragmatic, he points out that the possibility of having an assembly plant without a paint shop—which can cost about a third of the total tab—can be a real benefit.
In the meantime, the incremental gains will proceed. He doesn’t think there will be any revolutionary new materials, just more tweaking for what’s there. The same for process. “Over time,” Cundiff observes, “we can make a difference.”