2)Electrolytic cut-out process (electrolytic trepanning)

Electrolytic trepanning is a process of cutting out a desired shaped part from a substrate. The process itself is the same as electrolytic drilling but the product is not the hole but the center material of the hole remaining inside the electrode.

The electrolytic trepanning, therefore, uses the same equipment as the drilling process, with a small modification added to the electrode. The electrodes for drilling was insulated on the exterior for stray current prevention, but the electrodes for trepanning is insulated both on the inside as well as the outside. By doing so, a product with a diameter coinciding the cross section of the electrode can be produced. This is shown in [Fig.1].

3) Cavity machining (electrolytic sinking)

A cavity is a hollow feature. Sinking means "to bore a hole". It can be said that all electrolytic machining processes are variations of this Cavity machining. The notorious example is "EDM die sinking". Die and mold are made of hard cutting material and have complex features, so electrolytic machining is a good candidate and frequently used on forged parts. A notable benefit of this process is that the electrode consumption is low and many molds can be produced with one electrode. An example of a forging mold product is shown in [Fig.2].

4) Electrolytic contouring (shaping)

This is a process to create outside contours of parts. With the other electrolytic processes, electrolytes are supplied via the bores through the inside of the electrodes, but this method tends to leave traces of electrolyte outlet orifices on part surfaces. Special scheme is needed to avoid these traces. An electrode is placed on each side of the work piece, with the work piece held in the middle, and the electrolyte is applied into the gaps. This process is mainly used for contouring of turbine blades. It is most suitable to create surfaces with gradual curvatures that generate small fluid resistances.