Geometry and absorptance of the cutting fronts during laser beam cutting

The geometry of the cutting front and the cutting kerf was measured with an online high-speed x-ray diagnostic system. X-ray videos from fusion cutting of 10 mm thick stainless steel samples were recorded with a frame rate of 1000 Hz. A three-dimensional reconstruction of the time-averaged geometry of the cutting front and cutting kerf out of these images made it possible to apply ray-tracing for calculating the overall absorptance and the distribution of the absorbed irradiance at the cutting front. When increasing the feed rate, it was observed that the local inclination of the lower part of the cutting front with respect to the laser beam increased as well as the locally absorbed irradiance on the cutting front. This also leads to an increase in the overall absorptance with increasing feed rates.