A multi-physics CFD study on the part-to-part gap during remote laser welding of copper-to-steel battery tab connectors with beam wobbling

Remote Laser Welding (RLW) of dissimilar metallic thin foils (below 500 µm) has fundamental importance in battery pack manufacturing where high repeatability is a strict requirement. Since the welding process is very sensitive to part-to-part gaps, it is critical to understand the physical phenomena during melting, formation of the keyhole and solidification. This study has been designed to investigate the underlying physics of the welding process and understand the influence of the laser beam wobbling and part-to-part gap on temperature fields and metal mixing. A CFD multi-physics model has been implemented and then calibrated with experimental data. Two scenarios with part-to-part gap (0 and 100 µm) have been considered during lap welding of 300 µm copper to 300 µm nickel-plated steel, with circular beam wobbling. The study has highlighted that the part-to-part gap leads to uncontrolled metal mixing. Potential strategies for weld optimization are discussed throughout the paper.