WEAR OF MONOCRYSTALLINE DIAMOND TOOLS DURING ULTRAPRECISION MACHINING OF NONFERROUS METALS

In studying the wear behavior of diamond cutting tools, a pragmatic approach has been chosen in which the tool wear and the change in cutting forces have been specifically determined as a function of tool life. Several nonferrous metals, such as copper, aluminium, and electroless nickel, have been machined. The influence of microstructural characteristics, crystallographic orientation, and mechanical surface state of diamonds on tool-wear behavior is investigated in considerable detail. It has been found that wear behavior of diamond tools depends strongly on workpiece material, so that when machining aluminium, all types of diamond show considerable and almost the same degree of wear. However, machining copper and electroless nickel entails much subtler wear characteristics; in fact, great differences in wear resistance between different types of diamonds were discerned. Type II diamonds in particular, both synthetic and natural, appear to be highly resistant to wear. The best crystallographic orientation for wear-resistant diamonds depends on the way the cutting tools are used.