Industrial Automation Magazine India

First all-plastic brake pedal for battery-electric sports car

Published on : Wednesday 06-05-2020

High bending and torsional strength thanks to multi-axial fiber-layer structure in combination with high-stiffness tapes.

Cologne, May 20220 – In a battery-electric sports car, every gram of weight counts. That is why the first mass-production vehicle in this segment is using an all-plastic brake pedal. This safety-critical component has been developed by BOGE Elastmetall GmbH, a global provider of vibration technology and plastics applications for the automotive industry, in close cooperation with the LANXESS High Performance Materials (HPM) business unit. It owes its high mechanical strength and very low weight to a thermoplastic composite design. Its structure comprises an insert made from Tepex dynalite, a continuous-fiber-reinforced thermoplastic composite from LANXESS, and several tapes.

“The composite structure makes the brake pedal 50 percent lighter than a comparable steel design. The structural component meets the demanding load requirements thanks to the tailor-made fiber-layer construction of the Tepex insert and additional local tape reinforcement. Extensive automation allows the geometrically complex safety-critical component to be manufactured efficiently and in a way that is suitable for large-scale production,” explains Dr Klaus Vonberg, an expert in lightweight design at HPM’s Tepex Automotive Group.

The fully consolidated semi-finished products Tepex dynalite have a thermoplastic matrix that is typically reinforced with layers of continuous glass-fiber fabric. The brake pedal for the battery-electric sports car uses a composite structure with a polyamide 6 matrix, which contains unidirectional fiber layers inside and fabric layers with fibers arranged at 45° angles on the two covering layers. The inner layers are what give the component its excellent tensile and bending strength.

“This tailor-made fiber-layer structure and the combination of organic sheets and tapes have made it possible to reduce brake pedal weight even further while simultaneously achieving the exceptionally high level of mechanical characteristics that such a safety-critical component needs to provide,” says Dr Daniel Häffelin from the Innovation Center at BOGE Elastmetall. There are currently four different brake pedal designs in mass production based on an all-plastic version. For all component versions, the load paths are also optimized to suit the various torsion directions.

The brake pedals are manufactured in an automated process using hybrid molding in short cycle times suitable for large-scale production. The method integrates draping of the Tepex insert and the tapes in the subsequent injection molding process. The first stage of production involves aligning the tapes precisely using optical measuring systems and then positioning them on the Tepex insert so that they can be welded to it. This assembly is thermoformed and then back-molded with polyamide 66 by an injection molding process.