In this paper, laser-assisted machining (LAM) has been employed to machine hot isostatically pressed (HIPed) Si3N4 workpieces. Due to little residual flaws and porosity, HIPed Si3N4 workpieces are more difficult to machine compared to normally sintered Si3N4 workpieces. In LAM, the intense energy of laser was used to enhance machinability by locally heating the workpiece and thus reducing yield strength. In experiments, the laser power ranges from 200W to 800W and the diameter of workpieces is 16mm. While machining, the surface temperature was kept nearly constant by laser heating except for a short period of rise time of max. 58 seconds. Results showed as feed rate increases the surface temperature of Si3N4 workpieces decreases slightly, whereas the effect of depth of cut is disregardable. With a laser power of 800W, achievable maximal depth of cut was 0.7㎜ and feed rate was 0.03㎜/rev.
