The Investigation Of The Mechanism Of High Frequency Short Pulse Micro-Electrochemical Machining

In recent year, with the development of the advanced technology, the developing tendencies of the new and high technology products are more and more integrated, ultra-precisionly and miniaturization. So their parts become more and more small, machining accuracy should reach micron, submicron even nanometer.Electrochemical machimng (ECM) is an anodic dissolution process of workpiece in a flowing electrolyte where the shape of the tool as cathode is copied into the workpiece as anode with the removal of the anode ion by ion. It will be tremendous potential in the micro-manufacturing field with advantages as high machining efficiency, wide materials suit to fabricate, no residual stress and no heat treatment borne on the workpiece surface.Many researches and applications show that, by using high frequency pulse power supply the ECM precision and surface quality can be improved effectively. The basic process of High Frequency Short Pulses Electrochemical Machimng (HSPECM) is the high frequency cyclical interrupted electrochemical anodic dissolution instead of continual dissolution, it is caused by high frequency short pulses current instead of conventional direct current. With a series of special physical and chemical changes have happened in the machining gap, which has made the current efficiency improved and the machining gap reduced and the removed ability of anode enhanced, the machining accuracy and quality have been improved so highly that machining accuracy of HSPECM could reach micron. So it is very important for the application of HSPECM in micro-fabrication technologies to study the theory of HSPECM and optimize the machining parameters.The inter-electrode gap and electrolyte flow field in HSPECM are investigated in this paper by the electrode processing power theory. With analysis of the structure and characteristics of double-layer interfaces between electrode and solution, the equivalent circuit resistive and capacitive of anodic and mathematical model are presented, based on the model the simulation and study between the voltage, frequency,duty cycle of pulse power,initial gap and the inter-electrode gap is done in the MATLAB. And the theory of removed ability in special area in HSPECM is reasonable explained, the mathematical expression of the limited balanceable inter-electrode gap is derivated, the applicable conditions of the model are expressed, too.In the electrolyte flow field the effect of gas of cathode and the pressure wave caused by the radial activity of bubbles are discussed, and simulation and study between the voltage,frequency,duty cycle of pulse power and characteristics of the pressure waves and the influences of the electrolyte flow field is done in the MATLAB based on the pressure wave model, which is derivated by hydrodynamic model and explosion theory.Experiments on processing are carried out on the micro-ECM , which successes to make micro- cathode and micro-holes. And the influences of pulses on the bottom gap , the side gap by the voltage,frequency,duty cycle of pulse power is investigated by experiments. In the end, the study done in this paper and some advice for HSPECM continuous research are put forward.