Scattered across the exhibit floor at the North American International Auto Show in Detroit are hints of a new future for automotive plastics, used in ways and parts that many people will not notice.
There are LEDs just making their way into headlights, which require automakers, molders and material suppliers to come up with new ways to focus that light.
There are new opportunities for thermoplastic composites in lift gates that also free up a designer's ability to reshape the rear end of a car.
And hidden beneath the car, there's a new emphasis on under-the-body aerodynamics that is leading carmakers to use plastics to channel air flow and improve performance.
``The thing that's surprised me the most, but also excited me the most, is that the things that are going to be important for vehicles is to make them more energy efficient,'' said Bruce Benda, North American vice president of auto glazing for polycarbonates at Bayer MaterialScience LLC of Pittsburgh. ``Energy efficiency will come through in aerodynamic styling and in more technology like LEDs and lightweighting technologies like composite body panels,'' Benda said at the show, held Jan. 11-17.
LED headlights
LEDs made their first appearance at the rear of the car, in brake lights and turn signals. Now they are beginning to make a splash in the front.
A handful of vehicles now are being offered with LED headlights, including limited editions of General Motors Corp.'s Cadillac Escalade, some Audi AG vehicles and as an option on the new hybrid Lexus HS 250h, due out later this year.
For carmakers, LEDs offer up lower energy use — so there is more power available for satellite navigation or in-car entertainment, for instance — and they are unlikely to burn out during the car's life.
They also allow for more design freedom. GM used LEDs on its Cadillac Converj electric concept car as part of a horizontal line of lighting that's intended to be a specific Cadillac design element.
LEDs combined with thermoplastic light pipes are used to turn directional lights into design accents. The Chevrolet Camaro has a standard headlight but uses an LED and light pipe to create a circle around the headlight for a daytime running light.
But LEDs come with new challenges, including the question of how to focus the light into a strong and intense beam that meets federal and safety standards. The answer is another piece of plastic: PC molded into a very specific shape and thickness called a collimator lens.
``Any time you're seeing an LED headlamp, you're seeing some kind of collimator lens,'' said Paul Platte, Bayer director of new business industry innovation in automotive.
But it is not an easy part to process.
``One of the old tenets of plastic molding was to keep the thickness the same, and on a collimator lens, the centers are sometimes twice as thick as the outer layer,'' Platte said. ``You have to gate this in a very particular way and control the process in a particular way so you don't get sink marks. This is a lens, and if you get a little blemish on the surface, then your prescription is way off.''
Thermoplastic lift gates
Take a look at the rear end of the typical sports utility vehicle or crossover vehicle, at the place where the tailgate meets the bumper fascia. The lower fascia bumps out away from the lift gate, providing space for an impact zone, so that a steel gate does not take the brunt of the damage in a low-speed crash.
But Ford Motor Co.'s new Lincoln MKT crossover eliminates that space and allows the tailgate to rest nearly flush against the outer line of the fascia, by using thermoplastic rather than steel for the lift gate's outer body panel. The flexible panel also allows Ford to create a specific design vision.
``If you start to look at the trends in concept designs with these vehicles … you start to look at the desire for a seamless transition from the gate to the lower fascia, and you're not going to accomplish that in a low- or medium-impact crash without a [thermoplastic] composite solution,'' said Thomas Pilette, vice president of product and process development for Magna International Inc.'s Decoma International division.
Auburn, Ontario-based Magna is making the MKT's rear gate by uniting a magnesium structure with a long-glass-fiber thermoplastic polyolefin outer layer.
``A composite is going to move with the impact and then it's going to rebound,'' Pilette said. ``And if the damage is too high and you actually break that panel, you can replace it easily. It can be forgivable.''
Unlike the vertical dent-resistant body panels on the first generations of Saturn cars, engineering designed around the use of thermoplastic composite makes it possible to control thermal expansion issues, so the MKT does not have large gaps between body panels, Pilette said.
While the MKT uses a metal structure, Magna also is working on future programs that could marry structural plastic to a thermoplastic interior panel for a complete module to be delivered to automakers.
The resulting part will allow for greater design flexibility, while helping to lower weight — a major push from carmakers, he said.
``It doesn't matter who [the automakers] are. It's about weight, weight, weight, mass, mass, mass,'' he said.
Underbody panels
Automakers have done a lot of work to streamline the car body and improve the way it moves through the air. Now they are looking beneath the car, and using plastic to improve air flow between car and road.
Toyota Motor Corp. touts its use of underbody panels, such as the skid plate beneath the front end of the car, to boost the fuel performance of its new Lexus HS 250h and Prius hybrids.
GM uses what it terms a ``belly pan'' on the Converj electric car to help extend the vehicle's range.
The next question, Bayer's Platte said, is how to take interest in under-the-body aerodynamics to the next stage and combine it with the push to decrease weight. That leads to more potential for structural plastics to replace some metal parts.
``We're investigating now how you can replace some of those metal components in some of the underbody steel or ladder and frame parts that are on the road now with a urethane structure,'' he said.
Horizontal structural urethane could be used to tie together vertical steel structures, and also reduce the number of parts from 15 to 20 steel stampings to just a handful of hybrid steel and plastic structures.
At the same time, Platte said, the plastic could be molded both to help air flow smoothly beneath a car and to be channeled where needed to help cool an electric battery.