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Plastic Encapsulated Window Technology Inducted into SPE Automotive Hall of FamePlastic Encapsulated Window Technology Inducted into SPE Automotive Hall of Fame

Plastic encapsulated windows, which were first used in 1978 by GM, have been named the 2024 Hall of Fame winner by the Automotive Division of the Society of Plastics Engineers.

Stephen Moore

January 13, 2025

2 Min Read
1978 Oldsmobile Cutlass Cruiser
Plastic encapsulated rear windows graced the 1978 Oldsmobile Cutlass Cruiser.Image courtesy of General Motors

The industry’s first plastic encapsulated windows — fixed rear quarter windows used on the 1978 General Motors Co. A-Body Chevrolet, Pontiac, Oldsmobile, and Buick wagons — have been named the 2024 Hall of Fame winner by the Automotive Division of the Society of Plastics Engineers (SPE). 

GM body engineers were looking for a way to “glaze” fixed windows that would improve: 

  • Acoustics and water penetration via better sealing;

  • aesthetics through a cleaner, less-obtrusive appearance;

  • costs in both the labor and piece prices. 

The solution was provided by tier molders Donnelly Mirror and Lamar Plastics who developed an injection molding process by which a plastic molded gasket was directly applied to the window glass. These rather large, fixed windows had a UV-stable, polyvinyl chloride (PVC) gasket frame molded around the glass edges.

Rubber replacement

Encapsulation involves the injection molding of a polymer trim, shaped precisely to fit the vehicle body to the periphery of the glazing. It also provides the opportunity to incorporate additional styling features — fixing mechanisms and even hinges for opening windows in minivans and estate cars within the molding. The typical encapsulation process uses injection and reaction injection molding (RIM). The window is set in a mold; the mold clamps the glass, generally a few millimeters from the edges; and an elastomeric resin is injected to form the glazing seal/gasket. A butyl rubber sealant is applied at the assembly plant that installs the window assembly.

Related:Redefining Display Technology for Automotive Windshields

Technology has broad impact on auto industry

Plastic encapsulated window technology has made a significant impact on the auto industry including:

  • Replacing rubber gaskets with plastics (both thermoplastic and thermoset);

  • improved window aesthetics, size tolerances, reduced noise, enabled “flush” glazing, and lower drag coefficients;

  • improved window forming contours (less edge “off form” needed for injection molding);

  • introduction of PVC, polyurethane RIM, and thermoplastic elastomers for window molding;

  • enabling both tempered and laminated glass encapsulation;

  • reducing OEM labor and piece price costs.

Nominations must meet several criteria

To be considered for a Hall of Fame award, an automotive plastic or composite component must have been in continuous service in some form for 15 years or more, made a significant and lasting contribution to the application of plastics in automotive vehicles, and is broadly adopted or expanded upon in the automotive industry. Additional criteria include that the nomination be game changing; successful worldwide; innovative in materials, process, and application; and still in use. This application certainly qualifies as encapsulated windows are now an industry standard globally and the technology has expanded to being used in windshields (reaction injection molded PU), backlites (fixed or lift type back windshields), and sunroofs.  

Related:Bumpy Road Ahead for Automotive Sector

About the Author

Stephen Moore

Stephen has been with PlasticsToday and its preceding publications Modern Plastics and Injection Molding since 1992, throughout this time based in the Asia Pacific region, including stints in Japan, Australia, and his current location Singapore. His current beat focuses on automotive. Stephen is an avid folding bicycle rider, often taking his bike on overseas business trips, and a proud dachshund owner.

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