Machining of Single Crystal Sapphire Using Wear with Glass

Abstract

Sapphire has high hardness and chemical stability. When a sapphire is used as a product, it must be machined into a desired shape. However, it is very difficult to machine the sapphire because of its high hardness. By the way, the sapphire reacts with silica at high temperature and under high pressure. Using this phenomenon, a single crystal sapphire is machined by tool wear during cutting of glass which contains the silica because the cutting point attains the high temperature and high pressure. The rake faces of the sapphires are a-plane, c-plane and r-plane in the cutting experiments. The removal rate is small when the rake surface is c-plane. The glass chips during the machining are inspected by EPMA. The elements of the sapphire exist around the glass chips. The mechanisms and removal rate of the machining of the sapphire are examined by a simple model from these results.