DETROIT — The day of reckoning is coming soon for automotive polycarbonate window glazing.
A major push continues by automotive and resin suppliers to convince carmakers worldwide that plastic windows are ready to be installed on future vehicles. They can recite the reasons: Polymeric windows are significantly lower in weight than glass, resist shattering and can be molded with window encapsulation systems to save costs.
In fact, they project that shortly after 2000, many vehicles will feature fixed side windows made of a coated polycarbonate resin.
For more than a decade, the technology has been under heavy development. It is not a Jules Verne fantasy to expect results soon, said Gerhard Hirmer, general manager for product and process development with Concord, Ontario-based Decoma International Inc., a large Tier 1 supplier of exterior vehicle components and systems.
``We've spent a lot of time developing and refining the technology,'' Hirmer said. ``Our work has helped build confidence to a high level in the auto industry. Every automaker is looking at our glazing technology.''
Hirmer said European carmakers, more concerned with fuel efficiency than cost, have taken the lead in testing plastic glazing techniques. However, he added that they might not be the first to put a vehicle into mass production.
``But I would say the North American experience has also been good,'' he said. ``When they're ready to move, they will move quickly.''
But plastic windows also cast a less-rosy reflection. Some carmakers and government officials wonder whether plastic glazing will ever prove itself to be a worthy substitute for glass due to concerns over scratch resistance, safety and cost issues.
Plastic glazing also faces a deadline. Since August, the National Highway Traffic Safety Administration in Washington has allowed U.S. carmakers to install plastic for side windows, such as quarter or sail panels, behind the rear seat. Before the narrowly worded regulation became effective, NHTSA did not allow plastic glazing for windows necessary to view traffic.
However, the federal law has only a two-year grace period before it is reviewed. By midsummer 1998, NHTSA must decide to continue the regulation, expand upon it or discontinue it.
It is no sure bet that NHTSA will keep the regulation, said Stephen Summers, NHTSA crash-worthiness engineer and team leader for the agency's glazing area. The agency first must review test results — some provided by outside suppliers and some conducted internally — to determine if plastic windows are safe enough for on-road vehicles.
Although PC windows generally are considered shatterproof, a big concern of NHTSA is occupant safety when vehicles roll over. NHTSA data shows that in the United States, more than 3,000 people annually are thrown through windows, many of them during rollovers.
``We're a long way from making a recommendation,'' Summers said. ``We're not yet convinced that plastic breaks in a friendly manner during a rollover instead of in sharp pointy pieces. We also need to be certain that if the plastic doesn't break, the impact won't cause a skull fracture.''
Last fall, the agency launched a cooperative agreement with glass manufacturer Pilkington Libbey Owens Ford of Toledo, Ohio, to test all-plastic windows and laminated polymers placed between glass sheets. The research is taking place at NHTSA's Transportation Research Center in East Liberty, Ohio.
Richard Sahler, director of global marketing for Libbey Owens Ford, said that he is cautiously optimistic about the future of plastic glazing.
``It's too early to predict what the combination of materials and attachment systems will be,'' Sahler said. ``But it is reasonable to anticipate that we'll see some vehicles on the street in the 2002-2005 time frame with material other than tempered glass.''
Summers said suppliers could help sway the review process by doing tests on plastic glazing.
To that end, both Decoma, a subsidiary of automotive supplier Magna International Inc. of Markham, Ontario, and resin supplier GE Plastics of Pittsfield, Mass., have made a significant investment to develop glazing technology and market it to automakers.
The development process starts with a sheet of PC, similar to what is used for automotive headlamps. The resin can be injection molded or thermoformed and then coated with a silicone material to protect against surface abrasions or scratches.
In base material comparisons, PC can be at least triple the cost of glass. But by molding an entire window encapsulation system, instead of just the window, the price differential can be narrowed, Decoma's Hirmer said.
``When you do a system cost comparison, it can turn in favor of plastic because you save steps and components,'' he said. ``The best opportunity is for us to be involved early in the design process. At that point, it's a delusion to think that plastic is more expensive than glass.''
Besides developing its Lexan PC for glazing, GE also has installed polymeric side and rear windows in five test-model Chrysler Corp. Dodge Caravan minivans. The vans — which replace 105 pounds of glass with 59 pounds of PC — are equipped with sensors to measure the effect of solar and ambient temperature exposure.
The vans will be used in Florida, Arizona, Massachusetts and Michigan to measure how well the plastic windows wear under different weather conditions, said Janice Gryzwa, industry manager for glazing at GE Plastics.
``We'd like to drive them to the carmakers' doors to show them how well the windows hold up,'' Gryzwa said at GE Plastics' Southfield, Mich., office. ``We think they address some of the issues that they're most concerned about, especially weathering in a variety of environments.''
Decoma hopes to show automakers similar conclusions. At the company's headquarters, a large section of its research area is devoted to glazing. The area includes more than a half-dozen injection presses, with clamping forces of 1,000-4,000 tons, that mold PC window systems for testing.
With a bevy of activity, windows could become one of the hottest new automotive uses for plastics within the decade. Still, some carmakers wonder if plastic glazing ever will achieve critical mass.
``There's no question the technology's improved,'' said Roger Heimbuch, director of materials and fastening engineering at General Motor Corp.'s Technology Center in Warren, Mich. ``But there is a question whether it's
improved enough to be used on a vehicle. We've been looking at this for years and years, but we're still running into some of the same problems.''
To date, no major car manufacturer has committed to using plastic windows in high volumes. In North America, the only applications in mass production are Corvette Targa roofs sold by General Motors and a sliding soft top for Chrysler's Dodge Viper.
In addition, BMW of North America Inc. uses several interior layers of plastic for the front windshield and side and rear windows on its 1997 750iL luxury car. The windows include a sheet of both polyurethane and PC extruded into a glass windshield.
The vehicles use one of the first applications of trilaminated plastic in a car window, said BMW spokesman Rob Mitchell. The carmaker is billing the windows as break-resistant security glass to prevent theft and improve insulation.
According to GE test results, PC windows can resist impact as much as 200 times better than glass while cutting weight in half.
But a major sticking point has been the potential for scratches and abrasions. Carmakers wonder about the effects of a metal ice scraper across a piece of plastic, not to mention what sand, car-wash brushes or a mere cloud of dust could do over time, Heimbuch said.
Hirmer said that while PC will never beat glass in some performance aspects, the technology has made quantum improvements in scratch resistance — enough, at the very least, to allow its use on a vehicle.
``The current system is quite good. The question is how much scratch resistance you really need on a car. If you take a metal scraper across the car's paint, it will scratch it just as easily as on a plastic window,'' Hirmer said.
One way that problem is being solved is through hard coatings. New variations include a silicone coating chemically bonded with a ceramic material to improve hardness and flexibility. That coating is being developed by Pittsburgh-based resin supplier Bayer Corp.
``Carmakers need to see more fleet test results before committing to a glazing program,'' said Mark Witman, Bayer's director of technology. ``Scratches have been a major hurdle, but this coating approaches the scratch resistance of windows in our tests.''
Even those skeptical of the technology, such as Heimbuch at GM, said that there might not be a better time than now for the material to go into mass production.
``I'm looking out my window at our parking lot, and I see a lot more vehicles with small quarter windows than ever before,'' Heimbuch said. ``They'd be perfect candidates for [plastic] window glazing —but we have to get to the point first where it's to our advantage to use it on the road.''