It is used as electrode for Electric Discharge Machining. Electric Discharge Machining has been widely used in various fields such as moulds and components making. In recent years, it strives for high performance for super high speed, super high accuracy and super fineness. As a cutting tool, EDM wire draws more attentions than before because it is an important factor for the technology improvement of the industry. Therefore, the quality requirements to EDM wire will become more and more important.