Numerical modelling of a one-dimensional laser drilling problem

Abstract

In laser drilling, laser pulses of specified energies and periods irradiate the surface of the workpiece to gradually heat, melt and vaporize the material until a shaped hole of the desired depth and diameter is reached. Despite being the fastest method available for producing small diameter holes, rate of laser drilling varies upon different parameters. Therefore, it is crucial to understand the impact of each parameter on hole quality in order to manufacture holes according to a specific requirement with minimal cost and time. There are several methods available to model the laser drilling problem, such as the Finite Element Method (FEM), Finite Volume Method (FVM), various meshless methods, the element‐free Galerkin method have been developed to solve even up to 3D laser drilling problems.

In this research, a numerical modelling of the 1D laser drilling problem, using the Finite Volume Method (FVM) coupled with an implicit scheme, is developed to predict the motion of the moving boundary. The motion of the moving boundary will therefore be used to predict the drilling speed. Further examination will be done to and identify parameters that will affect the efficiency of the drilling.

The developed model can illustrate the trends of 3 parameters, area of laser spot, A ,vaporization temperature, uv and power supplied by laser, Qο on the speed of laser drilling, as well as determine the temperature at distinct locations on the metal along the laser drilling axis. It was found that increasing A decreases the drilling speed, increasing uv leads to a decrease in the rate of laser drilling, while increasing the Qο leads to an increase in the rate of laser drilling.