Development of Diamond Tools for Superprecision Machining with Compositionally Graded Layers from Silicon Carbide Shank to Diamond Chip.

Diamond cutting tools are getting increasing uses for superprecision machining. For conventional diamond tools, a vibration known as slight waviness is generated to deteriorate the machining accuracy because of the low stiffness of silver solder containing active metals used to join a diamond chip onto a metallic alloy shank. In order to overcome this problem, a diamond tool with silicon carbide shank by reaction sintering was developed. Numerical calculation by the finite element method (FEM) was carried out to clarify the thermal residual stresses between the diamond chip and silicon carbide shank with and without compositionally graded joining layers. The FEM calculation clearly showed that thermal stress between the diamond chip and silicon carbide shank was greatly reduced by inserting the compositionally graded layers. The fabrication process and performance of the developed diamond tool were also described.