The principle and discharge difference of micro-hole EDM machine

The principle of micro-EDM is not fundamentally different from that of ordinary EDM. The surface quality of its machining mainly depends on the size and depth of the etch pits, that is, the energy of a single discharge pulse; and its machining accuracy is closely related to factors such as the discharge gap, the stability of the process system, and the electrode loss. Micro EDM also uses pulse power supply to transmit high-frequency discharge energy to the discharge gap, and realizes the removal of materials by the comprehensive effect of high temperature thermal effect, so as to achieve the purpose of machining the work-piece.

1. The discharge area is very small
The electrode of fine EDM is generally between <5 ~ 100μm. For an electrode <5μm, the discharge area is less than 20μm2. When discharging on such a small area, the distribution range of the discharge point is very limited, which is very easy to cause. The concentration of discharge location and time increases the instability of the discharge process and makes micro-EDM difficult.

2. The discharge energy of a single pulse is very small
In order to meet the requirements of electric spark discharge with small discharge surface and ensure the dimensional accuracy and surface quality of processing, the removal amount of each pulse should be controlled within the range of 0.10 ~ 0.01μm, so the amount of each discharge pulse must be reduced. The energy is controlled between 10 – 6 ~ 10 – 7 J, or even smaller.

3. The discharge gap is very small
Since EDM is non-contact machining, there is a certain machining gap between the tool and the work-piece. The size of the discharge gap varies with the processing conditions, ranging from several microns to hundreds of microns. The control and variation rules of the discharge gap directly affect the machining quality, machining stability and machining efficiency. Especially in the micro-EDM machining, the machining of micro-holes accounts for the majority, and the size and stability of the discharge gap are the key to the success of micro-hole machining.