Edge Sharpening and Surface Modification of PcBN Cutting Tool by Pulsed Laser Grinding

Abstract

PcBN cutting tools have excellent characteristics such as high degree of hardness and low chemical reactivity, so they have potential to replace high precision grinding of hardened steel with high precision cutting. PcBN might be more efficient tool material if improvement in formability, and good surface modification can be achieved. In order to solve these problems, Pulsed Laser Grinding (PLG) is applied to a shape cutting edge and to finish a rake face. After processing by the PLG, shaped cutting edges were observed with a scanning electron microscope (SEM) and measured with contact- type profilometer. As a result, cutting edges processed by the PLG are similar or shaper than that by conventional diamond grinding. In addition, as a one of effects of surface modification, The Vickers microhardness of rake faces increases by about 10 present after PLG. On the other hand, according to frictional test with lateral force microscopy, the coefficient of friction of rake face decreases by half of ordinary surface. Depending on these advantages of PLG, high precision turning of hardened steel with 58HRC in hardness by use of the tool processed by PLG can demonstrate good performance rather than a commercial tool with diamond grinding finish.