At the 18th-annual Automotive Composites Conference & Exhibition (ACCE) sponsored by the Society of Plastics Engineers (SPE), a team comprised of automaker Groupe Renault (Boulogne-Billancourt, France), tier one Webasto SC (Les Châtelliers-Chateaumur, France), toolmaker and molder AARK-Shapers (La Séguinière, France), and resin supplier Polyscope Polymers (Geleen, The Netherlands) won the event’s People’s Choice award for the most innovative composite part chosen by conference attendees. The winning nomination was for the first composite guide rails on a rollerblind sunroof module for the panoramic roof on two models of multipurpose vehicles (MPVs) from Renault called the Scenic and the Grand Scenic and have been in commercial production since 2016. Representatives from Webasto and Polyscope accepted the award during closing ceremonies and also co-presented a technical paper on design and development of the guide rails.
The move from aluminium extrusions to thermoplastic composite lowered part weight and operating noise, simplified sunroof construction and installation on the vehicle assembly line, reduced costs, and increased headspace in the passenger compartment. Webasto engineered the injection molded rails to include a high level of functional integration while simultaneously reducing part count, assembly operations, and manufacturing time, cost, and complexity. XIRAN SGH30EB — a fiberglass-reinforced copolymer of styrene maleic anhydride and acrylonitrile butadiene styrene (GR-SMA/ABS) from Polyscope — was optimized both to ensure high bond strength to the polyurethane adhesive used to mount the glass to the module and the module to the body-in-white (BIW) roof structure, and to ensure high dimensional stability critical for smooth operation of the rollerblind. Clever tooling by AARK-Shapers enabled eight GR-SMA/ABS composite parts for the sunroof module to be molded in a family tool that also features modular blocks allowing both Scenic (five-seater) and Grand Scenic (seven-seater) rails to be molded in the same tool without using costly tooling action (slides) or separate tools. Each rail was molded in two pieces and ultrasonically welded after demolding.
At Renault’s assembly plant, the new sunroof system, including the rollerblind, arrives fully assembled and pretested as a one-piece unit that is robotically bonded to the roof, eliminating two-to-three assembly steps and allowing an operator to be reassigned. The initial system cost reduction is around 20%. However, the new module has fewer parts and is expected to reduce long-term warranty costs as indicated by lower parts/million (PPM) defects and higher quality already seen at Renault. Another benefit is that a Z-axis element-stack reduction of ≈13 mm was achieved because the whole module is adhesively bonded directly to the body-in-white (BIW) roof structure instead of the conventional two-to-three-step process where rails are fastened with screws to the BIW and the module is then fastened to the rails. This not only provides more working space on the assembly line for workers, but also gives taller vehicle occupants more headspace during vehicle use. Additionally, no grease was needed and noise/vibration/harshness (NVH) was reduced during sunshade operation. Like aluminium, the composite rails are fully recyclable, but less energy is needed to produce them initially and to recycle them at end of vehicle life.
Industries: Automotive & Road Transportation