During the EDM process, an electric current crosses the gap between the electrode and the workpiece (spark gap) to erode and remove material from the workpiece. An EDM discharge pulse contains an on time and an off time element to complete a complete cycle. If the off time element is not sufficient to discharge the condensed debris, the spark gap reionization process will be very unstable due to the conductive debris floating in the gap region. If the spark gap ionization process is not properly controlled, a direct short circuit of discharge energy or an arc discharge (discharge energy concentrated to a single point instead of uniformly dispersed over the entire electrode surface) may occur, which may result in damage to the workpiece.
The EDM discharge process is a delicate balance in which the generator constantly adjusts and changes the on and off time values to stabilize the process, which is why the EDM process does not run at the set feed rate.
Electrical discharge machining (EDM), also known as spark machining, spark eroding, die sinking, wire burning or wire erosion, is a metal fabrication process whereby a desired shape is obtained by using electrical discharges (sparks).The electrodes are divided by the dielectric liquid. Once the voltage increases, the electrical strength between the electrodes expands, causing the dielectric fluid to rupture, and leaving an arc in its place.
Roughing | The number of sparks during roughing is low, but each spark has a high energy and generates a lot of over burning. The roughing process achieves rougher surface finishes and lower precision levels. |
Finishing process | Finishing achieves lower material removal rates and less over burning, but also produces finer/smoother surface finishes and higher accuracy. The finishing process is used after the roughing process, minimizing the amount of material that must be removed for the finishing operation. |
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