On the micro-modelling of surface roughness in pulsed laser machining

Abstract

Abstract The surface roughness and the evolution of its morphology of a pulsed laser irradiated aluminum workpiece, is investigated via numerical simulations and experimental measurements. A three-dimensional transient thermo-structural finite element model is developed to simulate the machining process. The developed finite element material model considers the effects of plastic strain, strain rate and temperature, along with a fracture model. For the experiments, a single laser pulse of 6 ns duration and 0.7 mJ of energy at 532 nm is employed as the heat source, and the surface roughness is measured using white light interferometry set-up and related experimental diagnostics. A step-like linear approximation is used to model the surface roughness. A satisfactory agreement between the experimental data and the simulation results is found. This preliminary study aims to contribute to a better understanding of the initial physical processes involved in pulsed laser machining considering the influence of surface roughness and is beneficial for industrial applications such as laser polishing, engraving and cutting.