The dynamics of laser surface modification

The mechanisms involved in the production of surface features of protruding material formed by the interaction of a laser beam and a metallic substrate are investigated aiming to optimise the process efficiency. A relationship between laser induced surface features and filament breakup theory has been established. Results indicate that for the production of features the geometry of the protrusion with a filament critical aspect ratio over 6.0 ± 1.0 is required. In addition results show the surface tension, viscosity and density of the molten material, and the dynamics of the process dictate the characteristics of the forming feature. Using filament breakup and spatter production equations surface feature processing parameters can be predicted as demonstrated by the three metallic materials used in this study: Aluminium 5000 series, Stainless steel 304 and Ti-6Al-4V, all of which show consistent results.