EDM working principle 电火花加工工作原理

When EDM is performed, the tool electrode and the workpiece are connected to the two poles of the pulse power supply, respectively, and immersed in the working fluid, or the working fluid is charged into the discharge gap. The gap automatic control system controls the tool electrode to feed the workpiece. When the gap between the two electrodes reaches a certain distance, the pulse voltage applied on both electrodes breaks down the working fluid to generate a spark discharge.

A large amount of heat energy is instantaneously concentrated in the microchannels of the discharge, the temperature can be as high as 10,000 degrees Celsius or more, and the pressure also changes drastically, so that the local minute amounts of metal materials on the working surface are immediately melted, vaporized, and splashed into the working fluid in an explosive manner. In the medium, rapid condensation occurs and solid metal particles form and are carried away by the working fluid. At this time, a tiny pit mark is left on the surface of the workpiece, and the discharge is suspended for a short time, and the working fluid between the two electrodes is restored to the insulating state.

Immediately afterwards, the next pulse voltage breaks down again at another point where the two electrodes are relatively close to each other to generate a spark discharge, and the above process is repeated. In this way, although the amount of metal to be removed by each pulse discharge is very small, because there are tens of thousands of pulse discharges per second, more metals can be removed and the productivity is certain.

While maintaining the constant discharge gap between the tool electrode and the workpiece, the workpiece electrode is continuously fed to the workpiece while the workpiece metal is removed, and finally the shape corresponding to the shape of the tool electrode is machined. Therefore, as long as the shape of the tool electrode and the relative movement between the tool electrode and the workpiece are changed, various complicated profiles can be processed.

The tool electrode is commonly used for electrical conductivity, high melting point, easy processing of resistance to corrosion materials, such as copper, graphite, copper-tungsten alloys and molybdenum. In the machining process, the tool electrode also has a loss, but less than the amount of metal removal of the workpiece, and even close to no loss.

The working fluid acts as a discharge medium and plays a role of cooling, chip evacuation, etc. during the processing. Common working fluids are lower viscosity, higher flash point, stable performance media such as kerosene, deionized water, and emulsions.