Experimental Research On Electrochemical Machining For Micro Hole With High Aspect Ratio

Electrochemical machining (ECM), which removes the anodic material in terms of ion, appliesthe principle of anodic dissolution within the electrolyte and indicates a number of advantages such asstress free, deformation free, etc. Over the past few years, it has been the hot spot of research area inthe micro-machining academic circles. But there are some problems still not resolved in Micro-ECM,especially in the micro-hole machining with high aspect ratio. Because of limited micro space of gapbetween electrodes, it is very difficult to flush the electrolyte and remove electrolytic by-products inthe processing. As a consequence, the machining depth, precision and stability can not be achieved ona higher level.In this paper, a rotating cathode is employed in the micro-ECM process in order to enhance therenewal of electrolyte and transportation of dissolution sludge within micro interelectrode gap. Aseries of micro holes are drilled on the stainless steel (1Cr18Ni9Ti) and some processing parametersare investigated under varied machining conditions, e.g. cathode rotating speed, rotating direction,cathode shape and power supply. The main work includes:1.The experimental setup is designed and built according to the research goal, in which ahigh-speed rotating axis is integrated so as to carry out the turning of cathode. A specific cathodefixture into the rotating axis is used to resolve the radial runout of the electrodes.2. Micro cylindrical tool electrodes are fabricated by means of electrochemical erosion processand a sequence of micro tools are gained in range from80to150μm. Semi-cylindrical tool electrodesare produced by using electrochemical wire-electrode cutting method as well.3. The above mentioned Micro tool electrodes are applied to machine a series of micro holes onthe stainless steel with varied processing parameters in terms of cathode rotating speed, rotatingdirections, electrolytic types and processing voltages. The impacts of these parameters on the effect ofmachining depth are analyzed in the mean time.4.The impacts of different shape of cathodes on the processing depth of micro-hole are measuredby using cylindrical, semi-cylindrical and helix tool electrodes in a range of diameters. In addition,through-holes with high aspect ratio are obtained by using rotating tool electrode under optimizedmachining parameters which come from previous work on the stainless steel workpiece.