Pulse forming at laser beam micro welding

SHADOW® is a welding technique where one single pulse of a Nd:YAG laser with high feed rate is used to produce weld seams of several millimetres of length. In several applications this welding technique has replaced the spot welded seams and further conventional joining techniques like press fit or soldering. The laser power necessary for a good weld seam is mainly depending on feed rate, material and process stadium. At the beginning of the weld seam, more laser power is necessary to remove the oxide skin from the material surface and melt the material. Since the material is molten, less power is necessary to maintain the weld pool. An overheating of the melt pool has to be avoided as well. Cracks and spatter formation are affected by the different physical properties and should be avoided. Overlap welds and bead-on-plate welds are produced. High strength and reproducibility as well as good appearance are the main objective. In this investigation, the pulse forming for stainless steel (X5CrNi1810), copper (CuNi3SiMg) and brass (CuZn37) is optimised.