Improved Machinability of High Hardened Die Steel by Using Pulsed Laser Surface Treatment

摘要

In this study, pulsed laser surface treatment was carried out in order to improve machinability in the shape correction process by ball end milling for forging dies. The die steel with high hardened layer by ion nitrided process was used as a workpiece that was irradiated by pulsed laser, and then milling experiments were performed with inclined workpieces in order to simulate machining for walls of the dies with a draft. The machinability was evaluated from specific cutting force of the material, which was obtained from the cutting force components and the actual depth of cut calculated by tool deflection measured in the machining test. The results of improved machinability were shown as the hardness reduction of surface layer induced by the laser irradiation. Therefore, the laser irradiated surface responded to increase the actual depth of cut and uncut chip thickness, while the tool deflection and specific cutting force were small compared with those for non-irradiated surface.