EDM (Electrical discharge machining) drills is also known as electric spark punching machine, small hole drilling and fast hole drilling and start hole drilling . Its working principle is to use the continuous up and down vertical movement of fine metal copper tube (called electrode wire) as the electrode to carry out pulse spark discharge to remove metal from the workpiece. High temperature corrosion metal is produced by discharge between electrode and metal to achieve the purpose of perforation. It is used to process the pores of superhard steel, hard alloy, copper, aluminum and any conductive substance. EDM drills can process at least 0.015mm small holes, and also can process small holes with taper.