This process is used to cut plates and to make punches, tools, and dies from any conductive material, including hard metals that are too difficult to machine with other methods. It is also known as electrical discharge machining, is a process that uses an electrically energized thin wire to slice through metal. This method uses rapid, controlled, repetitive spark discharges from the wire to the work piece, thereby eroding the metal away. The work piece must be electrically conductive.