Micro electrical discharge machining using high electric resistance electrodes

- In order to decrease the diameter of discharge craters, high electric resistance materials such as single-crystal silicon are used for electrodes.
- When the electrode resistance increase, the peak value of the discharge current decreases, whereas the pulse duration increases.
- The diameter of discharge craters decreases by increasing the resistivity of the electrodes.
- By increasing the resistivity of the tool electrode, improved finished surfaces of Rz 0.03 μm are obtained.

In micro electrical discharge machining (EDM), because the material removal per single pulse discharge mainly determines the minimum machinable size of a micro EDM, decreasing the material removal per single pulse discharge is important. In this study, in order to decrease the material removal per single pulse discharge, high electric resistance materials such as single-crystal silicon are used for electrodes. Analytical results show that when the electrode resistance increases, the peak value of the discharge current decreases, whereas the pulse duration increases. In addition, the discharge energy decreases when increasing the resistance. Silicon is used as a tool electrode, and the effect of resistivity of the silicon tool electrode on the diameter of discharge craters generated on the stainless steel workpiece is examined. Experimental results reveal that with increasing silicon electrode resistivity, the diameter of discharge craters decreases. Because the diameter of discharge craters can be decreased to 0.5 μm, improved finished surfaces of Rz 0.03 μm are obtained.