Warwick University develops welding process for battery cases

On behalf of major automotive manufacturers, WMG at the University of Warwick developed an innovative and production-ready process for laser welding of aluminum battery cases. 

The WMG team selected the ALO4-O processing optics from Scansonic in Berlin, a leading manufacturer of laser processing systems. The ALO4-O was designed specifically for use on battery cases. The laser processing head combines the tactile seam tracking of the ALO product family with the laser beam oscillation of a remote optics.

Pasquale Franciosa, head of the laser beam welding laboratory at WMG, comments, “In our search for the best optics for our research project, the ALO4-O convinced us with a number of features: it combines near-field scanning optics, tactile seam tracking, fast modulation of the laser power along with beam oscillation. This allowed us to control the heat input to tailor the structure of the seam and ultimately eliminate weld cracks while maximising processing speed.”

Battery cases as a central element in the electric drive system

Battery cases form the interface between the vehicle’s underbody structure and the road. The design of these boxes has multiple requirements, such as crash resistance and stability, water and gas tightness; all while keeping manufacturing costs low. To save weight, more and more OEMs are using high-strength 6xxx aluminum alloys. However, its high susceptibility to hot cracking makes it difficult to process.

Convincing test results

During the test series, the project team was able to achieve significant improvements in three important parameters of the process compared to tactile welding without oscillation. First, beam oscillation at medium/high process speed (4.8 m/min) improved joint strength by up to 70 percent. Second, reduction of heat input by 50% for a target joint strength. Due to the optical combination of wire feed and beam oscillation, there was no need to use spots that were larger than the wire. This not only allows for a reduction in laser power and the associated thermal deformations, but also to save energy. Third, the tests showed a guaranteed gap bridging of up to 45% of the top material thickness with beam oscillation. This result is comparable even to a remote laser welding solution alone.

The project not only proved the feasibility of the technology, but also developed 1:1 prototypes for manufacturers to test. The laser application labs at both WMG and Scansonic are fully equipped to support further process customisation to meet manufacturing needs.

Contact: Pasquale Franciosa