EDM of micro-rods by self-drilled holes

With this method a rod electrode with negative polarity is rotated and fed into a plate electrode to form holes. After the rod electrode returns to the initial position, the axis of the rod electrode is off-centered from the center of the hole at a certain distance. The polarity of the rod electrode is then reversed, and the rod electrode is fed into the plate electrode, either with or without rotation. Since holes are formed by the rod electrode itself, the rod electrode can be machined very precisely. Since this method does not need initial positioning of the tool electrode with respect to the plate electrode, the operation is easy and short.