(1) EDM perforation
is the most widely used type of EDM. Commonly used in processing holes (round holes, square holes, polygonal holes, special-shaped holes), bent holes, 4qL, microholes, etc., such as cold stamping dies, wire drawing dies, extrusion dies, etc. The type of holes and small holes in the mold, nozzle and spinneret.
The dimensional accuracy of the perforation is mainly guaranteed by the size of the tool electrode and the gap of the spark discharge. The cross-sectional contour size of the electrode should be uniformly reduced by one processing gap than the predetermined hole size, and its dimensional accuracy should be one level higher than that of the workpiece, generally not less. IT7 level, the surface roughness value is less than the workpiece, and the straightness, flatness, and parallelism are not more than 0.01mm in the length of 100mm.
(2) EDM cavity processing
EDM cavity processing includes forging molds, die-casting molds, extrusion molds, bakelite molds, plastic molds, etc. Cavity processing is more difficult, mainly because it is not through-hole processing, metal erosion is large, the working fluid circulation is not smooth, the removal effect of electric corrosion products is poor, tool electrode loss can not be compensated by replenishment. Therefore, the productivity of cavity processing is low, and the quality is difficult to guarantee. In order to improve the machining accuracy of the cavity, pure copper and graphite with high corrosion resistance should be used as the electrode. In addition, some small plastic mold surface frosting treatment also uses EDM.