Welding of pure copper wires using a hybrid laser system with a blue diode laser and a single-mode fiber laser

Highly efficient welding of pure copper was achieved using a hybrid laser system, which combined a blue diode laser and a single-mode fiber laser. Pure copper is used as a motor coil for electric vehicles (EVs). However, the processing efficiency of laser welding for pure copper is low since it has a low light absorption rate for the wavelength of the fiber laser. In this study, a hybrid laser system, which combined coaxially with a blue diode laser and a high-power single-mode fiber laser, was developed to realize highly efficient laser welding for pure copper. The beam profile of hybrid laser was alimented to set a stair-shape beam at the processing point. To investigate the effect of the beam profile, the hybrid laser was irradiated onto a 3 × 3 × 20 mm3 copper wire for welding, and the molten volume of copper wire was evaluated. As a result, it was found that the molten volume with a blue diode laser became 1.8 times larger than that without it. Moreover, the welding efficiency of the hybrid laser was 1.45 times higher than that of the fiber laser only.