Numerical study of molten pool dynamics and thus bur formation in laser drilling of metals

Abstract

A 2D numerical model is developed to investigate the transient dynamics of molten pool and thus the bur formation mechanism in millisecond pulsed laser drilling process. The model features the utilization of the sharp interface method for accurate consideration of the complex boundary conditions on the hole wall and a comprehensive hydrodynamic calculation for both the gaseous and liquid phases. The model gives good prediction of the bur phenomena, and more importantly, provides detailed information regarding the multi-phase interaction and its effects on hole dynamics, also on the bur formation. It is shown that different substrate can cause different coupling effects between the vapor plume and molten pool and hence produce holes of different shapes. The model gives a basic study of the bur formation during the ablation process of different metals and shows a virtual technique for the visual of the movement of melt and vapor. And the obtained results show good qualitative correspondence with experimental data.