Measuring the Melt Flow on the Laser Cut Front

The flow characteristics on the laser cut front for 10 mm stainless steel AISI 304 (EN 1.4301) are studied in this paper using High Speed Imaging (HSI). The laser cut samples were produced with a 6 kW fiber laser with nitrogen gas assist. Previous work in this field has used unusual cutting parameters to make the experimentation easier. This work presents, for the first time, HSI results from standard commercially viable cutting parameters. This was made possible by the development of a new experimental technique. The results presented here suggest that the cut front produced when cutting stainless steel with a fiber laser and a nitrogen assist gas is covered in bumps which themselves are covered in a thin layer of liquid. Under the conditions shown here the bumps move down the cut front at an average speed of approximately 0.4m/s. The liquid flows at an average speed of approximately 1.1m/s. The average melt depth at the bottom of the cut zone under these conditions is approximately 0.17 mm.