Electric discharge machining(EDM) is a special machining method which makes use of the electric etching effect produced by the pulse discharge between electrodes immersed in the working liquid to remove the conductive materials. At present, EDM technology has been widely used in processing various materials with high melting point, high strength and high toughness, such as hardened steel, stainless steel, die steel, cemented carbide, etc. And used for processing molds and other parts with complex surface and special requirements.
The principle of electrical discharge machining is the workpiece and tool electrodes respectively connected to the pulse power of two different electrode polarity, based on the tool and the workpiece (positive and negative electrodes) between pulse spark discharge of electricity to removal in excess metal corrosion phenomenon, in order to achieve the workpiece size, shape and surface quality of the predetermined processing requirements.
In EDM, tool electrodes are commonly used with good electrical conductivity, high melting point and easy to be processed, such as copper, graphite, copper-tungsten alloy and molybdenum, etc. The working fluid is usually used in the medium with low viscosity, high flash point and stable performance, such as kerosene, deionized water and emulsion. In addition, as a discharge medium, the working liquid also plays a role in the process of cooling, chip removal and so on.
