EDM is the use of a continuously moving thin wire (called a wire) as an electrode, the workpiece pulse spark discharge erosion metal, cut type a processing machine. Walking Sijia hours between wire electrode and the workpiece loose contact Gently press the discharge phenomenon. When the flexible wire electrode and the workpiece is generally considered close to the discharge gap (for example, 8 ~ 10μm), the spark discharge does not occur, even when the wire has come into contact with the workpiece, the microscope can not see the gap has been when, they often do not see to spark only when the workpiece electrode wire benders and offset a certain distance (a few microns to tens of microns) occur when the normal spark discharge. After this time the wire electrode feed per 1μm, does not reduce the discharge gap 1μm, but a little line between the electrode wire tension increases, the workpiece is increased a little lateral pressure, obviously, only to maintain a certain slight contact pressure between the wire and workpiece to form a spark discharge. Walking Sijia factory think between the wire electrode and the workpiece there is some kind of electrochemical insulation film generated media