Single-crystal diamond tools were earlier widely employed for the machining of non-ferrous metals, such as aluminum, copper, and gold. When used for machining these materials, it is attainable to achieve surface roughness in the nanometer range, superior to that of all existing tools. Severe tool wear can only be detected on cutting distances of the order of kilometers
[195]. Diamond tool wear is closely related to the material. Owing to the very low tool wear (mainly abrasive wear)
[196], it is known as an easy-to-cut material, as shown in
Fig. 19(a). To summarize, for the ultra-precision machining process of easy-to-cut materials, diamond tool experience less wear during machining, and the tool life can reach a distance of several thousand kilometers, as shown in Fig. 19(b).
