The Investigation On Micro-hole Manufactured By Micro-Electrochemical Machining

The metal sheets with micro-holes are widely used in many engineering fields, such as cooling holes in jet turbine blades, all kinds of nozzles, and so on.Electrochemical machining (ECM) is a course of the anodic electrochemical dissolution of metallic materials in an electrolytic medium utilizing the electrochemic -cal reaction. Due to the tiny size of metal ion, ECM shows a tremendous potential in the micro-manufacturing field, and much attention has been paid on it.This paper focus on micro ECM process of micro-hole in metal thin sheets, the following work has been done:1.Fabrication of micro-pin based on the machining principle of electrochemical etching is introduced. Machining parameters affecting the shape of micro-pin are discussed. Then a micro-pin electrode with 20μm diameter and 2000μm length is prepared using constant voltage in immobile electrolyte.2.According to the different needs of shaped tube and micro-pin, insulating methods are researched. A insulating film with 5μm thickness is coated onto the micro-pin with 30μm diameter.3.Experiments on fabrication of micro-holes by micro-ECM with cylindrical micro-electrodes are carried out, in which the micro-electrode is insulated with Parylene film. Effects of several process factors, such as current density, concentration of electrolyte, pulse duration, and duty ratio on machining accuracy are discussed. A micro-hole with 112μm diameter and 16μm machining space is successfully machined.4.Small hole is machined in metal with shaped tube. Effects of several process factors, such as current density, feed speed and feed depth on machining accuracy are investigated. A small hole with 1.0mm diameter and 0.1mm machining space is successfully machined.