Research On Precision Micro-hole Machined By EDM-ECM Combined Processing

With the development of science and industry, micro-holes have been widely used inmany fields of manufacture and life. Electrical machining technology has its uniqueadvantages in micro-hole machining, and it main involve electrical discharge machining(EDM) and electrochemical machining (ECM).EDM in able to machine various kinds of holes in any conductive material, theprocessing has no macroscopic force and low demand on the rigidity of the tool electrode.However, the recast layer will be generated in the wall surface of micro-hole by EDMprocessing. The recast layer is formed by molten material under the working fluid rapidcooling solidification and it often contains a lot of micro-cracks. Micro-cracks in recastlayer will tend to spread under alternating loads and which will cause fracture damage ofthe component. Electrochemical methods for the micro-hole processing, there will be agood quality of wall surface and no recast layer. But ECM has a low machining accuracyand efficiency, a high machining taper.In this paper, EDM-ECM combined processing experiment to obtain micro-hole withhigh machining accuracy and surface quality was done. First processing principle andcharacteristics of EDM and ECM were analyzed respectively, a combination of twoprocessing methods called EDM-ECM combined processing was raised, and thenprocessing mechanism and advantages of EDM-ECM combined processing wereexplained.Second, an electrochemical machining system was designed on self-developedmicro-EDM machine tool. The hardware platform of electrical combined processing wasset up and its control system-specific features the preparation was programmed. A subtleelectrode producing method by electrical combined processing is put forward. Principle,advantages and producing process of the method were explained in detail. Cylindricalelectrode, cutting edge electrode and shaped electrode for after experiment wereproduced in this method.Last, the effect of EDM and ECM parameters on efficiency in micro-hole drilling isdiscussed,200μm diameter micro-hole with a depth-diameter ratio of5, taper0.0075andgood surface quality was get by EDM-ECM combined processing successfully.