Investigation on the pulsed Nd:YAG laser drilling of IN718

We report on an experimental study of the pulsed Nd:YAG laser drilling of IN718 for cooling holes in aero-engine components. The holes produced in this study are angled at 30^o to the workpiece surface and were mainly produced by a spiral drilling technique. The design of experiment (DOE) using the Taguchi method was employed, and various process parameters such as laser power, drilling speed, assist gas pressure, focal position and a number of drilling passes are considered. After the process, all holes were characterized to investigate the effect of process parameters on the geometrical and metallurgical features of drilled holes. The optimum set of parameters to maximize hole quality was established by the Taguchi analysis. In the second stage of this study, the process performance of the spiral drilling was compared to traditional laser drilling techniques such as percussion and trepan drilling. The performance of different drilling methods was evaluated in terms of an exit hole size and drilling time. This study also involved trials to enhance drilling performance by using O₂ assist gas and moving focal position.