Electrical discharge machining (EDM) is a special machining method that uses the electric erosion produced by pulse discharge between two poles immersed in the working fluid to erode conductive materials. It is also called electric discharge machining or electroerosion machining, and is referred to as EDM in English. Tool electrodes commonly use corrosion-resistant materials with good conductivity, high melting points, and easy processing, such as copper, graphite, copper-tungsten alloy, and molybdenum. During the machining process, the tool electrode also suffers loss, but it is less than the amount of metal removed from the workpiece, and is even close to no loss.
2，working principle
The principle of EDM is based on the electrical corrosion phenomenon during pulsed spark discharge between the tool and the workpiece (positive and negative electrodes) to remove excess metal to achieve predetermined processing requirements for the size, shape and surface quality of the workpiece.
When a pulse voltage is applied between the two electrodes, and a proper gap is maintained between the workpiece and the electrode, the working fluid medium between the workpiece and the tool electrode will break down, forming a discharge channel.
Instantaneous high temperature is generated in the discharge channel, which melts or even vaporizes the surface materials of the workpiece. It also vaporizes the working fluid medium, rapidly thermally expands and explodes in the discharge gap. A small part of the material on the surface of the workpiece is eroded and thrown out, forming tiny particles. Electric corrosion pits.
After the pulse discharge ends, after a period of time, the working fluid is restored to insulation. The pulse voltage acts on the workpiece and tool electrode repeatedly, and the above process is repeated, and the workpiece material is gradually eroded away.
The servo system continuously adjusts the relative position of the tool electrode and the workpiece, automatically feeds, and ensures that the pulse discharge proceeds normally until the required parts are processed.
