Electrical discharge machining (EDM) has long been the answer for high accuracy, demanding machining applications where conventional metal removal is difficult or im-possible. 

Known by many other names, including spark machining, arc machining and (inaccu-rately) burning, the EDM process is conceptually very simple: an electrical current passes between an electrode and a workpiece which are separated by a dielectric liq-uid. The dielectric fluid acts as an electrical insulator unless enough voltage is applied to bring it to its ionization point, when it becomes an electrical conductor. The resulting spark discharge erodes the workpiece to form a desired final shape.