Scaling laws for thick-section cutting with a chemical oxygen–iodine laser

Almost all laser-assisted materials processing involves melting, vaporization and plasma formation which affect the utilization of laser energy for materials processing. To account for the effect of these phases, an effective absorptivity is defined, and a simple mathematical model is developed for the cutting of thick-section stainless steel using a high power chemical oxygen—iodine laser (COIL). The model is based on an overall energy balance, and it relates the cutting depth with various process parameters that can be used to predictively scale the laser materials processing performance to very thick sections. The effects of various process parameters such as laser power, spot size, cutting speed and cutting gas velocity on the cutting depth are discussed. The results of the mathematical model are compared with experimental data. Such a comparison provides a means of determining the effective absorptivity during laser materials processing.