High-Performance Welding of Copper with Green Multi-kW Continuous-wave Disk Lasers

We present application results of welding copper with multi-kW truly continuous-wave Disk Lasers at the green wavelength of 515 nm. By spatially combining three commercially available 1 kW TruDisk 1020 lasers, 3 kW of green cw laser radiation is provided by a fiber with 200 mu m core diameter. We achieved the following highlights by applying this laser source to copper sheets of different thicknesses: Sputter-free full penetration welding of 0.7 mm thickness has been demonstrated with excellent quality and a feed rate of 25 m/min, much faster than comparable IR wobble processes. In deep penetration welding mode, high-quality welds with depths of 1 mm and 2 mm have been obtained with feed rates of 18 m/min and 8 m/min, respectively, even in thick copper sheets, i.e., at maximum heat dissipation. 3 kW of green cw radiation allow welding depths >3.5 mm. Having proven the large potential of multi-kW green cw lasers, we give an overview on the current lab results on the power scaling of the disk laser sources. We demonstrate >2 kW green cw power with a BPP of 2.5 mm.mrad, as well as >3 kW green cw power with a BPP of 5 mm.mrad, both devices being realized with a compact footprint of less than 1 m(2). Summarizing, our application results prove the high-power green cw disk lasers to be the perfect choice for high-performance welding of copper with an excellent quality.