Laser beam welding of zinc-coated sheets and quality control

This paper demonstrates that different possibilities for an overlap welding of zinc coated materials by lasers are developed in principle. In case of layer thicknesses above 5 Mym in the joining area weld seams which are nearly without pores can be achieved by adapted processing parameters as high line energy and a focus position at the bottom edge of the sheet. The use of additional assist gas flows or the engraving of knurlings enable to weld thick coated sheets. By means of a process monitoring from the processing side it is possible to detect the degree of full penetration and thus to control one aspect of the welding process and to ensure a constant seam quality concerning root detection and porosity.