WEAR CHARACTERISTICS OF DIAMOND TOOLS IN MACHINING CERAMICS

Wear characteristics of natural diamonds used to machine ceramic materials at a depth of cut of 2 mu m and as speed of 1600 m/min were investigated. The diamond tools used for the machining tests were inspected using the Laue back reflection technique and scanning electron microscopy (SEM). Wear characteristics of the diamond tools appeared to be influenced by the material properties of the ceramics being machined, the build-up on the tips of the diamond tools, and the crystallographic orientations of the diamond crystals. Three wear patterns were identified: single-flat wear, double-flat wear, and micro-chipping wear. The single-flat and double-flat wear patterns were primarily observed in machining silicon nitride and alumina; the microchipping wear pattern was observed in machining silicon carbide. The wear rate for the microchipping pattern was found to be one of two orders of magnitude higher than those for other wear patterns. Silicon nitride wore the diamond tools faster than alumina did; however, it often formed built-up tips which reduced the wear of the diamond tools.