Potentials of Process Monitoring During Laser Welding of Electrical Steel Laminations

The increasing demand for highly efficient electric motors for traction applications leads to novel challenges for electric motor manufacturers. With the use of more advanced motor designs and materials, production processes need to be adapted or even reinvented. To reduce iron losses in ferromagnetic components, the stator and rotor core is laminated into thin electrical steel laminations. Depending on the requirements, different joining processes are used for fixing the shape of the lamination stack. As the stators of large traction drives are subject to high mechanical loads, welding processes are mainly used for this process step. In addition to conventional TIG welding, laser beam welding is gaining more and more importance for the processing of electrical steel laminations. The high level of automation, good seam stability and the possibility to weld thin sheets are reasons for using laser welding in this application domain. However, due to the complexity of the laser process and the multitude of influencing variables, it is quite challenging to find optimal process parameters. Furthermore, it must be ensured that the high welding quality once achieved is maintained over time. In this paper, the influence of different welding strategies is investigated and potentials of different process monitoring methods are analyzed.