A Truing Technique for Flattening Fine Diamond Grains on the Hemispherical Working Surface of an Electroformed Tool

A truing technique for fabricating the tip of an electroformed diamond tool of 0.1 mm diameter and 4 μm mean grain size with a hemispherical shape and flattening the cutting edges of diamond grains on the tool working surface was developed. A polycrystalline diamond (PCD) tool of 0.5 μm diamond grain size and 10 mm diameter was employed as a truer. It was confirmed through the truing test that the rough surface of the PCD truer generated by electric discharge truing should be partially flattened to eliminate scratches and removed chips adhering onto the tool working surface. In addition, truing conditions that enable the flattening of sharp cutting edges on a tool working surface along the hemispherical tool profile were determined by conducting a truing test in which both the revolution speed of the tool and the rotation speed of the truer were varied.