Electrical Discharge Machining (EDM) MachineDuring electrical discharge machining, the tool electrode and the workpiece are connected to the two poles of a pulse power supply and immersed in a working fluid, or the working fluid is filled into the discharge gap. The tool electrode is fed towards the workpiece through a gap automatic control system. When the gap between the two electrodes reaches a certain distance, the pulse voltage applied to the two electrodes will break down the working fluid, generating a spark discharge. A large amount of thermal energy is instantaneously concentrated in the fine discharge channel, with temperatures exceeding ten thousand degrees Celsius and rapid pressure changes, causing a small amount of metal material on the working surface to instantly melt, vaporize, and splatter into the working fluid, where it rapidly condenses to form solid metal particles that are carried away by the working fluid. At this point, a tiny pit mark is left on the surface of the workpiece, and the discharge pauses briefly, allowing the working fluid between the two electrodes to regain its insulating state.

Immediately after, the next pulse voltage breaks down at another point where the two electrodes are relatively close, generating a spark discharge and repeating the above process. Thus, although the amount of metal removed by each pulse discharge is small, due to thousands of pulse discharges occurring every second, a considerable amount of metal can be removed, resulting in a certain production rate. Under the condition of maintaining a constant discharge gap between the tool electrode and the workpiece, while removing metal from the workpiece, the tool electrode is continuously fed towards the workpiece, thereby machining a shape corresponding to the shape of the tool electrode. Therefore, by changing the shape of the tool electrode and the relative motion method between the tool electrode and the workpiece, various complex profiles can be machined.

The tool electrodes for electrical discharge machining are commonly made from materials with good conductivity, high melting points, and ease of machining, such as copper, graphite, copper-tungsten alloy, and molybdenum. During the machining process, the tool electrode also experiences wear, but it is less than the amount of metal removed from the workpiece, and may even be close to negligible.

The working fluid serves as the discharge medium, inElectrical Discharge Machining (EDM) Machinethe machining process, it also plays roles in cooling and chip removal. Commonly used working fluids are those with low viscosity, high flash points, and stable performance, such as kerosene, deionized water, and emulsions.