Analysis of heat effects in laser cutting of steels

Efficient control of laser cutting processes is closely related to knowledge of heat effects in the cutting front and its surroundings, Similar to other machining processes using high power densities, in laser cutting processes it is very important to monitor the heating phenomena in the workpiece material due to heat input. In laser cutting processes with oxygen as an auxiliary gas, cutting energy is a combination of laser beam energy and the energy of tbe exothermic reactions occurring in the cutting front. The presence of oxygen in the process increases cutting efficiency, but also causes additional physical processes in the cutting front that render a more detailed analysis of the cutting phenomena difficult. The aim of this article is to analyze the emission of infrared rays from the cutting front with a photodiode, statistically analyze the temperature signals, and optimize the laser cutting process based on a critical cutting speed, The measured infrared radiation temperature signal was, on the basis of calibration, converted into a temperature that was related to the formation of macro- and microstructures and to the change in microhardness in the surface layer of the cut. On the basis of experimental results, it was proved that heat effects in the cutting front decisively influenced the quality of cut. Finally, factor analysis was used to establish statistical relations among variables of the laser system, variables of the cutting process, and geometrical characteristics of the cut.