Task
Lightweight construction with multi-material-components is the key for sustainable and resource-efficient electromobility. The performance of hybrid structures, in this case an intrinsic metal-FRP-composite (FRP: fiber-reinforced polymer), is strongly dependent on the joint strength of metal and organic sheet. Within the research project performance and capability for series production of inline surface structuring of semi-finished metal parts by laser radiation for 3D-hybrid-parts is investigated. This enables direct adhesion by micro-scale interlocking.

Approach
Generating optimized micro-structures requires the determination of appropriate laser parameters such as pulse duration, wavelength and beam shape. Furthermore comparative studies on surface pretreatment with respectively without bonding agent and with respectively without laser structuring will show dependencies on mechanical stability as well as on corrosion behavior. Additionally customized laser system technology for process acceleration by parallelization and robotics will be developed to reach the required cycle times within the application.

Results
Preliminary investigations by laser beam joining of micro-structured metals with thermoplastics have shown that the joint strength is significantly dependent on the roughness of the surface and the bottom of the structure. In contrary there is no significant dependency on structure orientation or distance between trenches. After applying this knowledge to the proposed application, an improved adhesion quality between metal and FRP has been achieved. Further improvements on the joint are currently investigated. Parallelization of this structuring process is achieved by laser system technology including a spatial light modulator (SLM) for the generation of arbitrary beam geometries. In addition a robot is used for component handling.