The demonstrator part is produced in under three minutes.
Cranfield University’s Aurele Bras and Andrew Mills developed the process for the rapid production of lightweight carbon fibre parts as part of an EPSRC-funded project run by CIMComp. Hexcel, Cranfield and Metisse Motorcycles then collaborated on a composite demonstrator to validate the process and its benefits within high-rate manufacturing applications such as automotive.
An aluminium footrest bracket was chosen as the component, with all parties working together to optimise the part design for composite production. A detailed stress analysis, steel tooling design and fabrication were carried out before arriving at a finished prototype that was over 50% lighter than the original component. Hexcel’s HexMC-i moulding compound with HexPly carbon fibre UD prepregs were selected for the project.
All mounting holes and attachment points were moulded in their final shape and position, with the demoulded part ready to use with no secondary machining steps. As a result, overall production time for the composite bracket was just under three minutes in a lab environment, with a complete cycle time of less than two minutes being deliverable with an automated production cell, Hexcel reports.
The finished part, made from combined prepreg and HexMC-i (which is made from chopped fibre), weighs just a small percentage more than a fully continuous fibre prepreg solution. The Cranfield team is also said to have shown that this material combination delivers a significant performance and weight improvement over traditional SMC solutions that may be considered too heavy for key composite structural parts. Hexcel’s snap-cure HexPly M77 resin is used in both the HexMC-i and HexPly UD prepreg.
“Our collaboration with Cranfield and Metisse Motorcycles has validated the use of a HexMC-i and HexPly UD hybrid part design in replacing complex cast or forged metallic parts that could not previously be formed with composites in a cost-effective high-rate production process,” says Claude Despierres, Sales & Marketing Director – Automotive at Hexcel. “This demonstrates the effectiveness of the technology for components such as battery boxes, brackets, enclosures and even steering or suspension parts, that all could be made lighter and more rapidly with this new production process.”
Industries: Automotive and Road Transportation