1. The pulse energy density delivered between the two electrodes should be large enough. After the spark channel is formed, the pulse voltage does not change much. Therefore, the current density of the channel can represent the energy density of the channel. The energy density is large enough to locally melt or vaporize the processed material, thereby forming a corrosion mark (pit) on the surface of the processed material to realize EDM. Therefore, the channel generally must have a current density of 105-106A/cm2.
The discharge channel must have a sufficiently large peak current so that the channel can be maintained during the pulse. In general, maintain the peak current of the channel not less than 2A.
2. A reasonable distance must be maintained between the tool electrode and the workpiece electrode. Within this distance range, the pulse voltage can continuously break down the medium and generate spark discharge, and it can also meet the requirements of medium deionization and discharge of erosion products after the spark channel is extinguished. If the distance between the two electrodes is too large, the pulse voltage cannot break down the medium and produce spark discharge. If the two electrodes are short-circuited, there is no pulse energy consumption between the two electrodes, and it is impossible to realize electro-erosion processing.
3. The medium must be filled between the two electrodes. When performing material EDM size processing, there is a liquid medium between the two poles (special working fluid or industrial kerosene); when performing material EDM surface strengthening, there is a gas medium between the two poles.
4. The discharge must be a short-time pulse discharge. The discharge duration is generally 10-7-10-3s. Due to the short discharge time, the heat generated during discharge cannot be diffused in the processed material, thereby limiting the energy effect to a small range and maintaining the cold pole characteristics of spark discharge.
5. Pulse discharge needs to be repeated many times, and multiple pulse discharges are dispersed in time and space.
There are two meanings here: one time, two adjacent pulses do not form a channel at the same point; second, if the pulse discharge occurs in a certain area within a certain time range, then in another period of time, The pulse discharge should be transferred to another area. Only in this way can carbon deposits be avoided, and then arcs and local burns can be avoided.
6. The electro-corrosion products after pulse discharge can be discharged out of the discharge gap in time, so that the repetitive discharge can proceed smoothly.
In the actual production of EDM, the above process is completed in two ways. On the one hand, the spark discharge and electro-corrosion process itself has the inherent characteristics of removing the corrosion products; other discharge products (such as the vapor of the medium) other than the corrosion products can also promote the above process; on the other hand, some must be used Artificial auxiliary process measures, such as circulating filtration of working fluid, flushing and pumping measures used in processing, etc.