Quantitative Analysis of the Temporal Distance between Melt Waves on the Cutting Front Apex during Laser Fusion Cutting of Stainless-Steel Sheet Metal with 1 Micron Wavelength

Instabilities of the melt flow dynamics on the laser cutting front cause loss of quality due to the formation of striations on the cut flank. Only individual aspects of mechanisms of striation generation during laser cutting are understood. Further evaluations of the melt flow dynamics inside laser cutting kerfs regarding characteristic temporal and spatial variables of the cutting process and their dependences are still necessary. Within this paper the melt flow dynamics during laser cutting of 6 mm thick stainless steel using a disk laser with a laser power of 5 kW are visualized and analyzed by means of in-situ high-speed video diagnostics (>100,000 fps). For that purpose, an advanced algorithm is used to detect the temporally and spatially resolved melt waves sliding down along the cutting front apex. The cutting depth-dependent analysis of the temporal distance between the melt waves reveals only a low dependence on the cutting velocity.