MM4R

Topic and objectives

Lightweight vehicle structures such as the automotive component “cockpit cross member” addressed in the project are a key factor on the road to resource-efficient mobility. In addition to technical and economic criteria, environmental and social aspects are playing an increasingly important role. In recent years, hybrid construction methods have become established in lightweight construction, combining material, design, and functional lightweight construction. The use of reinforced plastics in combination with steel can significantly reduce environmental impacts compared to aluminum/magnesium structures, for example. The combination of thermoplastic fiber-reinforced composite (FRC) hollow profiles, organic sheets, and injection molding offers further functional advantages: With just a single material system, which is also easily recyclable (e.g., GF/PP), maximum design freedom can be achieved.

Approach

Fraunhofer IWS contributes its many years of expertise in the field of laser-based surface modification. Prior to composite manufacturing, the multi-material interfaces are specifically and individually pretreated with a laser by introducing so-called “anchor geometries” into each joining partner. This means that no additional bonding agents are required for the subsequent joining process, ensuring the recyclability of the component.

Results

The realization of three form-fit and partially material-fit connections (FKV to metal, FKV to FKV, and FKV to injection molding) usually results in increased composite strengths (compared to bonding). The transfer of the laser processes from 2D samples to the complex, three-dimensional shape of the cockpit cross member was achieved through the laser system symbiosis of robot handling and fast opto-mechanical X-Y-Z beam deflection. The latter not only enabled the achievement of industry-compatible process times, but also the creation of oppositely angled anchor geometries for a multilateral load situation in real-world applications.