Corner wear directly influence shape of the cavity. Heaviest electrode wear occurs

at the corners. Orbiting of the electrode relative to the workpiece is the most common

machining strategy proposed by researchers for compensating the tool wear. It involves the electrode tool making a planetary motion producing an effective flushing

action, thus improving part accuracy and process efficiency

Normally the relation between wear is 99% over the piece and 1% over the electrode. So, if the electrode change the shape with the machining, this wear affect the measure of the cavity. This changes affect the quality of the part.

During Electric Discharge machining, the parameters selected determines the final surface roughness and  electrode wear rate.

This general question can naturally not be answered in two or three sentences. The correct answer is already that the surface roughness and the wear of the selected process parameters depend.

The corner or edge wear is the main factor for a high machining accuracy, which has its cause in the fact that at the edges of the inhomogeneous electric field strength becomes the greatest and in this region the purge no longer is usually ideal.

The percentage is the wear of the removal rate is dependent on several things. A basic trend is that with short pulse durations of wear greatly increases and decreases for long pulse durations or is constant. One reason is that the main effect of the wear arises upon ignition of the spark. For these reasons, separate ignition modules are used, the only to have a minimum current.

Now you can still explain some more effects and still consider how large the working surface is and how effectively acts flushing, ......

Corresponding publications can be found in my reading list or for special designated applications can discuss it in more detail.