Multiple Micro-holes Manufactured By Micro-Electrochemical Machining With Multiple Cylindrical Micro-electrodes

Electrochemical Machining (ECM) is a processing technology, in which the metallic workpiece as anode is produced based on anodic dissolution in electrolyte. ECM appears to be a very promising metallic micro-manufacturing technology, because the process could machine workpiece ion by ion. Parts with multiple holes of meso scale have been widely used in aerospace, weave and precise mechanism industries fields. ECM shows its potential in fabrication of parts with multiple micro-holes, due to its unique advantages. Key techniques to stable machining of micro-screen plate by micro-ECM are mainly investigated in this dissertation.Mechanism of formation of micro-pin based on the machining principle of electrochemical etching is proposed. Machining parameters affecting the shape of micro-pin are discussed. Then a micro-pin electrode with 20μm diameter and 1500μm length is fabricated using constant voltage in immobile electrolyte.The method to produce multiple cylindrical micro-electrodes by electrochemical etching is proposed. The cathode profile for the fabrication of multiple cylindrical micro-electrodes in electrochemical etching is optimized by analyzing and calculating the electric field distribution with Finite Element analysis Method based on the electrochemical etching theory to obtain uniform current density on anode. Furthermore, methods to control the shape and diameter dimension of multiple cylindrical micro-electrodes in electrochemical etching machining are proposed. Experiments on fabrication of multiple cylindrical micro-electrode process are carried out, and some results are discussed.A method to fabricate multiple micro-holes by multiple cylindrical micro-electrodes is developed. Experiments on fabrication of multiple micro-holes by micro-ECM with multiple cylindrical micro-electrodes are carried out. Effects of several process factors, such as machining voltage, feed speed, pulse duration, duty ratio, composition and concentration of electrolyte on machining accuracy are investigated. The results show that electrochemical reaction region could be significantly contracted with low machining voltage, short-pulse duration and duty ratio, low concentration passivity electrolyte. Based on the above experimental results, two technique methods which are stepped machining and low concentration passivity electrolyte combined over-feeding machining to reduce machining taper of multiple micro-holes are proposed and realized. Eventually, fabrication technology of metallic micro-screen plate with multiple cylindrical micro-electrodes by micro-ECM is developed, good roundness and uniformity of multiple micro-holes is achieved.