An experimental investigation on laser assisted waterjet micro-milling of silicon nitride ceramics

Abstract Laser assisted waterjet (LAWJ), a novel technology, is applied in micromachining brittle material with nearly thermal damage-free. This paper presents an improved process for micro-milling silicon nitride ceramic for the first time. The differences between laser assisted waterjet, laser ablation and liquid assisted waterjet process had been discussed. The laser heated and soften target material could be expelled by the waterjet easily. The waterjet also acted as a coolant for minimizing heat damage efficiently. In order to obtain an accurate model for predicting the channel depth and surface roughness, the experiments were involved by using Response Surface Methodology (RSM). Main parameters, such as cross-feed, laser pulse energy, waterjet pressure and traverse speed, and their interactive effects were analyzed through ANOVA and graphical contours. The experiments demonstrated that all parameters’ direct effects were significant to depth and surface roughness, and the interaction between laser pulse energy and waterjet pressure was the most significant one in all interaction factors. The process parameters’ selection consideration was derived from the desirability function by RSM. The predicted models were effectively validated by the experiments.