This study deals with the heat treatment on the edge of a die using YAG laser on-the-machine tool. First, the temperatures based on a theoretical model during laser irradiation were investigated in order to prevent the melting phenomena of the workpiece surface. Second, heat treatment experiments on the edge of a workpiece were carried out using this system. Quenched part was observed by an optical microscope. As a result, it was confirmed that the calculated results were in good agreement with the experimental ones. Finally, the edge of a lawn mower blade was treated by the selected condition from above results.
