Influence of inclination angle on spatter behavior at welding with lasers of strong focusability

Thin disk lasers as well as fiber lasers are distinguished by their strong focusability and high efficiency. The stronger focusability can be used for an expansion of the application range. Weld seams of unprecedented high aspect ratios can be achieved which are only known from the electron beam welding until now. Based on results of thin disk and fiber laser experiments it has been shown in earlier publications that the influence of the divergence angle on the achievable welding depth increases dramatically for lower spot diameters. The evaporation rate which is mainly occurring on the front keyhole wall is dependent on the aspect ratio of the keyhole. Due to this there is a decrease of the number of spatters and their range of ejection angle due to a smaller focus diameter (d_f=200 µm) or higher laser power. The evaporation direction and therewith the number of spatters can be influenced by the inclination angle of the focused beam. In association with an increase of the inclination angle in forward direction the spatter behavior can be improved.