High mechanical demands are placed on battery cases as the heart of modern electric vehicles. On behalf of major car manufacturers, WMG at the University of Warwick in the UK tested welding processes for optimizing aluminum battery housings using lasers. In extensive laboratory tests, the ALO4-O processing optics from Scansonic were convincing in several respects.

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.

Dr. 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 maximizing 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 customization to meet manufacturing needs.

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About Scansonic MI GmbH

Scansonic offers systems and solutions for laser welding, laser brazing, laser cutting and laser hardening as well as optical sensors and process monitoring systems. The products are used especially in automotive engineering, rail vehicle construction and electrical power engineering. Scansonic MI is the world market leader in laser-based joining systems for car body construction. The company is part of the medium-sized Berlin.Industrial.Group. (B.I.G.) with headquarter in Berlin and around 350 employees. www.scansonic.de