PET film reinforces glass in retractable panoramic roof

A proprietary tear-resistant PET film developed by Webasto (Rochester Hills, MI) and Madico (Woburn, MA) enables a fully retractable panoramic roof system to meet all strength and performance requirement with thinner high strength fully tempered glass. A proprietary extrusion process and a unique laminating process for the 0.24-mm-gage film, which is carried out in an autoclave to eliminate bubbles, are employed in the manufacture of the assembly. Webasto has also developed a similar film together with Saint Gobin Performance Plastic (Livonia, MI).

The roof, installed in the Ford Lincoln MKZ, also incorporates unique plastic fasteners and retainers in place of steel clips for cost and weight reduction, as well as hard-coated polycarbonate trim panels in place of acrylic for improved scratch/mar performance and dimensional stability.

The PET film enabled use of fully tempered glass which meets FMVSS 205 requirements. Tempered glass is lower in cost than non-tempered and also tougher.

Processors involved in production of the system are Cooper-Standard (Novi, MI) and ARaymond (Grenoble, France), the latter being the molder of the fasteners. Polycarbonate (Lexan 143) was supplied by Sabic Innovative Plastics (Pittsfield, MA), while polyacetal (Hostaform S9363) for the fasteners was supplied by BASF (Ludwigshafen, Germany). The tooling supplier for the class A PC trim panels was Delta Tooling (Auburn Hills, MI), while Elite Plastics supplied the tooling for the fasteners. The system supplier is Webasto.

Steel clips, retainers, polyvinyl butyral (PVB) films with semi-tempered glass, and acrylic trim or painted steel panels are the industry standard. The new solution is 20% lighter. Furthermore, the PC composite outer panel offers improved strength and NVH (noise, vibration, and harshness) performance.