Car window regulators crank up nylon molders' prospects.

* The next time you raise or lower your car's side window, think of injection molded nylon. Though not especially glamorous, it could be the next big plastics application. That's the hope of Mertech Intellectual Properties, developer of a nylon-based window-lift system called the Dual Rack & Pinion Window Regulator (DRPWR). The company claims its new design delivers major reductions in weight and part count and makes window movement more efficient compared with steel adjustors currently used in most car windows.

Mertech's system will debut in late 2004 on a high-volume North American car platform. The lift assemblies will be supplied by Dura Automotive, Rochester Hills, Mich. Dura holds exclusive global rights to make and supply RackLift DRPWR units for Ford, Daimler-Chrysler, Renault-Nissan, and Volkswagen vehicles.

Mertech is negotiating with other window-regulator makers interested in supplying DRPWRs to additional OEMs. Ronald Sohr, Mertech president, expects a shift to nylon window regulators to occur in a decade or less. Some 48 million car-window regulators are sold each year in North America.

Compelling benefits

Conventional arm-and-sector and drum-and-cable window regulators consist of up to 35 mostly metal parts requiring labor-intensive assembly. These regulators weigh 4.5 to 7 lb and need grease to maintain a gliding motion. In contrast, the DRPWR is grease-free, has only 11 parts, and weighs only about 2.5 lb. About 1 lb of that is steel brackets, and the remaining 1.5 lb are molded nylon.

In Mertech's design, motor and glass are driven by two intermeshed gears that travel simultaneously along a ladder-like rack. The one-piece, 5-in.-wide, and 14- to 22-in.-long racks are injection molded of lubricated and glass-reinforced nylon 66. Ten other parts (base, supports, and gears) are molded in the identical formulation.

Paul Fenelon, a Mertech partner and inventor of the DRPWR, says a common nylon means that moisture build-up (and tolerance variances) in the multi-part mechanism are kept uniform, simplifying inventory and facilitating reclaim. Self-lubrication properties and the toughness and flexibility of nylon 66 hold breakage to a minimum. An advanced design expected to emerge in 2007 would convert metal brackets to plastic, cut part count to seven, and use lower-cost reinforced PP.

Sohr says his system cuts noise by 15% and reduces power draw by up to 80%. The DRPWR also increases scope for high-curvature (barrel-style) window designs currently favored by many buyers.

"Buyer benefits will pull this technology through in 2007-08," predicts Robert Cicala, Dura's director of engineering for Body & Glass Products. He cites the DRPWR's ability to operate efficiently over a more extreme range of temperatures and potentially deliver reduced warranty costs. Dura has ordered a two-cavity family tool for front and back racks with different drop angles. The tool will run on a 500-ton press.

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Mertech, Nashville, Tenn.

[phone], www.dualrackandpinion.com