Cutting of Alumina Ceramics by Single Crystal Diamond

Alumina-ceramic materials have been used instead of metals as structural components for aircraft, space craft and automotives. These materials are highly brittle, superhard and difficult to machine. Therefore, the cost of machining alumina-ceramic materials is considerably higher than that of metals. As a result a new cutting method has been developed to achieve lower-cost processing of the alumina-ceramic materials. In this cutting process, the corner of single-crystal octahedral diamonds in native state is used as the cutting edge. The applicability of this method to practical uses was evaluated by measuring the finished surface roughness and the tool life, and the strength characteristics of the materials, cut using this method, were investigated by the bending test. The cutting tool life is longer in the wet cutting method as compared with that in the dry cutting process. Moreover, when the abrasion side position of the diamond crystal edge corresponded to (100) of the crystallographic orientation, the cutting tool life tended to be longer. The maximum roughness of the finished surface was about 18μm and the material strength after cutting was decreased by about 15% compared to that before cutting.