Experimental Study Of Electrostatic Field-induced Jet Micro EDM

Electrostatic field-induced jet micro EDM is a novel micromachining method, in which the removal of material is realized by the discharge between sample and micro jet which is induced under intense electric field. Compared to the conventional EDM, it has several advantages, such as, lower single discharge energy, no tool electrode wear(TEW), and no need for the TWE real-time compensation. The machining mechanism has been disclosed and the influencing factors has been investigated by a serials of experiments. Moreover, influencing factors of diameter and density on porous silicon are also studied by orthogonal test.Foremost, different discharge types and creation conditions, translation conditions are investigated, and the machining mechanism with reverse polarities machining is also studied. During the machining, creation and translation conditions among corona discharge, glow discharge and spark discharge are studied respectively. The result shows that material can only be effectively removed under spark discharge machining. Moreover, it is also found that under different polarity machining the mechanism is different. During the positive machining, craters are mainly machined by electrical discharge process, however, electrochemical process can also appear in definite condition. During the negative machining, craters are fabricated only by electrical discharge process.Then, influencing factors of crater diameter are studied through experiments. The electrostatic field-induced jet micro EDM platform is improved. Experiments on single crystal silicon are carried out to analyze the relationship between crater diameter and factors such as nozzle inner diameter, anode-to-cathode distance, anode-to-cathode voltage and electrolyte concentration. Besides, influences of humidity, temperature and atmosphere flow are also discussed. Meanwhile, the 3D structure with 5μm in length, 1μm in width micro groove and a sequence of craters are machined successfully.Finally, machining techniques of porous silicon are investigated. The relationships between crater diameter, crater density and factors such as anode-to-cathode distance, anode-to-cathode voltage, electrolyte concentration and machining time are investigated. It is shown that anodeto-cathode distance is the key factor to crater diameter and electrolyte concentration is the key factor to crater density.