With the development of industrial production and the progress of science and technology, with a variety of complex structure and special requirements of the workpiece more and more, which makes the traditional mechanical processing methods can not be processed or difficult to process. Therefore, in addition to further development and improvement of mechanical processing, but also efforts to find new processing methods. EDM can meet the needs of production development, and in the application shows a lot of excellent performance, therefore, has been rapid development and increasingly widely used. EDM, also known as EDM (EDM). It is in the process of processing, so that tools and workpieces continue to produce pulsating discharge spark, by the discharge generated when the local instantaneous high temperature metal erosion. The advantage of EDM is that it can process difficult-to-cut materials, very hard materials (such as cemented carbide), all kinds of high-speed steel and even diamond, cubic boron nitride; there is an advantage that can be processed very delicate model.