Micro EDM deposition by using brass wire electrode in air

Proposed a new process technology of micro electrical discharge machining (EDM) beyond the traditional EDM concept. This method can deposit the brass wire tool electrode on the workpiece surface by pulse discharges between anode and cathode in air. At first, the basic machining parameters, which realize micro electrical discharge deposition, are prejudged according to the discharge phenomena in air and EDM basic theory. Afterwards, a lot of experiments were carried on an ordinary sinking-EDM machine tool. The results of experiments show that wire tool electrode materials, brass, can be deposited on steel workpiece surface. The diameter of micro fabricated cylinders is 100-240 microns, and the height is 1000-7350 microns. On some special machining parameters, a micro spiral structure can be deposited also, which is 100 micron in thread diameter and more than ten cycles. Excepting lots of experiments, the structure and properties of deposited substance were analyzed by SEM, spectroscopy analysis and micro hardness meter and so on. The results of analyzing the deposited cylinders show that the structure is multi-layer, which is beneficial for the further study of 3D scanning machining. The hardness is a little higher than the original metal. In this depositing process, element Zn of tool electrode is almost oxidized to ZnO. Element Cu is not oxidized, existing as solid Cu. Because the reactivity of Cu is weaker than that of Zn.