Exatec's Window of Opportunity

It wasn't that long ago the idea of using nylon instead of metal for engine intake manifolds or clear polycarbonate for headlight lenses was considered a pipe-dream.

It took years of hard work to get various auto maker and government specifications changed, but now plastic has taken over both these applications.

Vehicle windows, or glazing as they are known to vehicle designers, seem poised at a similar juncture. Replacing glass in vehicles with plastic is a concept that has been talked about for decades with lots of false starts, but the planets finally seem to be aligning in plastic's favor, thanks to growing concerns about fuel economy, changing designs and improved molding technology.

And it is possible that as new corporate average fuel economy regulations begin to phase in at the turn of the decade, new polycarbonate glazing applications will debut in North America.

Many new applications are being tested by auto makers, says John Madej, CEO of Wixom, MI-based Exatec LLC, which specializes in developing and licensing plastic-glazing technology.

A key tipping point came in 2005 when the National Highway Traffic Safety Admin. approved the supplier's signature product, Exatec 900-coated polycarbonate, for vehicle-glazing applications if prescribed test requirements were met.

Exatec delivered 430 prototypes to auto makers globally in 2007, about six times as many as the year before, Madej says.

The glazing technology supplier initially is targeting panoramic roofs and large fixed-glass panels, such as those found in lift gates and rear-quarter windows of SUVs and minivans. Using polycarbonate for roof panels and fixed-glass areas of a typical vehicle can save anywhere from 5 lbs. to 40 lbs. (2.3 kg to 18 kg) in a vehicle, depending on how much plastic is used, says Greg Adams, vice president and general manager of Sabic Innovative Plastics, Exatec's parent.

A Jeep Commander featuring a polycarbonate backlite, rear-quarter windows and roof “skylights” reduced weight 25 lbs. (11 kg), Madej says. However, using lighter plastic for the liftgate window also creates the opportunity for secondary weight savings, such as smaller struts and lighter structural brackets to hold the window in place.

Panoramic roofs made of polycarbonate, instead of tempered or laminated glass, already are picking up steam in Europe because they improve vehicle handling by reducing weight above the beltline.

The addition of a panoramic roof typically doubles the weight above the beltline vs. a conventional roof, requiring suspension modifications and other engineering tweaks to compensate. However, when panoramic roofs are designed with transparent polycarbonate plastic instead of glass, the weight of the roof system can be reduced 40% to 60%, compared with conventional glass systems, Adams says.

About a dozen models in Europe currently use polycarbonate glazing, including the Smart Fortwo. The Fortwo's roof is claimed to be one of the largest polycarbonate roofs ever. It is made of Bayer MaterialScience AG's Makrolon AG2677.

Exatec celebrated its 10th year in business March 8. It was founded in 1998 as a 50/50 joint venture between GE Plastics (a unit of General Electric Co.), and Bayer MaterialScience. It now is a wholly owned subsidiary of Sabic Innovative Plastics, part of petrochemical giant Saudi Basic Industries Corp., which purchased General Electric's plastics unit last year.

As part of its anniversary celebration, Exatec recently held an open house in Wixom to introduce its latest technologies and capabilities, including an upgraded coatings technology lab, a new injection-molding machine and a unique full-scale plasma system for continuously coating polycarbonate windows. Most of the technologies are aimed at enhancing durability, lowering costs and developments such as embedded antennas, electro luminescence and defrosters.

Defogging rear windows used to be a problem because plastic transmits heat far less readily than glass, but that issue now has been solved, Madej says. “This expansion to our Michigan facility enables Exatec to serve as a one-stop shop for the most advanced automotive-glazing solutions available,” he says.

While weight reduction is important, Sabic's Adams says auto makers also are getting more interested in polycarbonate glazing because it allows for greater design freedom and the ability to create a more distinctive appearance. Exatec engineers recently worked with Ford Motor Co. designers on two concept vehicles — the Lincoln MKT and the Land Rover LRX to show off the design capabilities of polycarbonate glazing.

Polycarbonate Strives to Change Window Technology
subscribers.wardsauto.com/ar/polycarbonate_window_technology/