A prototype automotive roof made from a Makrolon polycarbonate lamella may soon be an alternative to conventional fabric or PVC-based sliding and folding sunroofs, says its maker Bayer MaterialScience.
The roof incorporates transparency, sealing, opening and closing functions in a single plastic component that can be manufactured with just one process step. Florian Dorin, a specialist in Bayer MaterialScience's Automotive Glazing Team, says the development team designed the prototype using economical production technologies that will help speed its transition to full production.
To form the lamella roofs' hinges and seals, Bayer molds transparent and flexible polyurethane or silicone materials onto individual polycarbonate lamellae. The prototype features four flexible lamella segments. These so-called roof windows open and close separately. Tracks connect segments to a solid, transparent polycarbonate roof skin. A tube, also transparent, runs lengthways along the middle of the roof to accommodate the folded lamellae after the roof window opens. This creates a three-dimensional structure that makes the component more rigid than a flat lamella roof. It also significantly reduces the number of individual components.
The fact that the roof is made solely from plastics gives more design freedom, says Dorin. "Designers can create three-dimensional geometries that would push glass/metal combinations to their limits. There are cost savings thanks to integration of functions. For example, the prototype roof incorporates a wind deflector, two indicator housings and, in the end of the transparent central tube, a housing for the brake light. It would also be feasible to incorporate roof spoilers and antenna holders plus roof railing and water management components. Storage compartments and housings for interior lighting could also be molded onto the inside of the roof."