Thermal modelling of cutting front edge dynamic behaviour in high-power reactive CO₂ laser cutting

The sheer number of non-linear interacting factors responsible for the performance of laser cutting makes it impractical, in general, to investigate all the factors by experimental method only. To understand further the essential phenomena of the oxidation reaction in reactive CO₂ laser cutting, a mathematical model was created in this research to investigate the effects of cutting parameters on the cutting front edge dynamic behaviour. Understanding the effects of various parameters is important for improving the performance and quality of laser cutting. The reactive CO₂ laser cutting of a thin metallic plate utilizing a continuous-wave laser beam having a Gaussian intensity distribution was considered in this study. Both the beam absorptivity and the heat generated at the cutting front edge during the reactive cutting process were considered in this research. The numerical results of this work can be used to predict or estimate the variations in the location, speed and acceleration of the cutting front edge, given various gas compositions, gas pressures, cutting speeds and beam absorptivities. An on-line monitoring system for laser cutting was built, and a series of experiments was performed to record the fluctuating frequency of the cutting front edge. The results confirm that our theoretical results were in accordance with the related experimental results.