Experimental investigation on the cut front geometry in the inert gas laser fusion cutting with disk and CO2 lasers

Abstract

In recent years, several studies on laser beam fusion cutting demonstrated significant differences in the characteristics of the well-established CO2 laser cutting and cutting with solid-state disk and fibre lasers. The absorptivity behaviour of metals shows essential quantitative differences for the corresponding wavelengths of both laser sources as a function of the inclination angle between the laser beam and the material to be irradiated. In order to further the understanding of the involved phenomena, a series of cutting experiments with CO2 and disk lasers was carried out. Similar geometry of CO2 and disk laser beam in terms of focus diameter and Rayleigh length was used. In this work, the two dimensional stationary geometric shape of the cutting front is acquired by the longitudinal sections of the cut specimen. The cutting front geometry and the corresponding local inclination angle are related with the absorptivity calculated in each point of the cutting front. The effects of various laser processing parameters, as focal position and cutting speed, on the geometric shape of the cutting front have been analyzed systematically on steel sheet 5 and 8 mm thick.