Why does "breakdown" occur in EDM?

"Breakdown" is a very important concept in the EDM process. It not only has a direct impact on machining efficiency and quality, but also has a vital significance for the safe operation of equipment.

EDM is a non-contact microfabrication method, mainly through the heat generated by the discharge to erode the workpiece material. In this process, a strong electric field force is generated between the tool electrode and the workpiece, and when this electric field force is large enough, it causes the gas to ionise to form a plasma, and then the energy is transferred to the workpiece through the discharge.

In this process, if the energy of the discharge is too large, it will cause the insulation between the tool electrode and the workpiece to be pierced, forming a short circuit. This is known as "breakdown".

Breakdown is a common phenomenon in EDM, and its occurrence has a direct impact on the efficiency and quality of the process. Why does breakdown occur? There are several reasons:

1. The voltage of EDM is too high. In the machining process, if the voltage is set too high, it will lead to an increase in the energy of the discharge, thus increasing the possibility of breakdown.

2. The distance between the tool electrode and the workpiece is too small. If the distance between the tool electrode and the workpiece is too small, it will lead to too large electric field force, thus increasing the possibility of breakdown.

3. poor performance of the insulating material between the tool electrode and the workpiece. If the insulating material has poor performance, it will be easy to be punctured.

4. excessive ambient humidity. Excessive humidity can cause the dielectric's insulating properties to deteriorate, thus increasing the likelihood of breakdown.

Although breakdown will bring certain effects on EDM, as long as the influence of voltage, distance, insulating materials and environmental humidity can be mastered, the occurrence of breakdown can be effectively avoided.

For example, it is possible to choose the right voltage, maintain a proper distance between the tool electrode and the workpiece, use insulation materials with good performance, and control the humidity of the environment. The possibility of breakdown can also be reduced by changing the form of the discharge. For example, pulse discharge or impulse discharge can be selected, and these forms of discharge have a relatively small energy density and are less likely to produce breakdown.