Melt Flow and Cutting Front Evolution During Laser Cutting with Dynamic Beam Shaping

A dramatic increase in the industrial demands for tailoring the laser beam profile in laser cutting has led to significant performance improvements thanks to the recently emerging dynamic beam shaping technology. Nonetheless, the underlying reasons for such process improvements are not fully understood yet, and mainly theoretical assumptions are available. This paper uses several high-speed videography strategies to evaluate and compare the melt flow dynamics and cutting front geometry during 4 kW fiber laser cutting of 15 mm plates with static and oscillating beams. The absorption behavior on the cutting front is analyzed through trim-cut observation, and a substantial difference of around 40% is observed between these two laser beam intensity distributions. Moreover, a distinctive molten material ejection mechanism is found during linear beam oscillation, being beneficial for fusion cutting and detrimental for flame cutting. Finally, based on the experimental results, a former explanatory model from the literature is enhanced and further ways to optimize the beam profile during laser cutting are proposed.