Fabrication of an Electrode Insulated by Using Hot Dip Aluminizing and Micro-arc Oxidation Method for Electrochemical Microhole Machining

In this research, electrode insulation of the electrochemical machining tool has been produced by hot dip aluminized micro arc oxidation techniques. In order to form an effective layer on the tungsten carbide tool and achieve higher precision, the tool will then be micro-arc oxidizing, convert the aluminum-rich into aluminum oxide insulating layer. Withstanding Voltage of the tool is being tested afterward by sodium chloride electrolysis method, and the surface and the cross section is being observed. Eventually, the tools were examined and discussed for their machining performance by ECM drilling through stainless steel plate. We were expecting to produce a precise and better insulation. By reducing ECM stray effect, the precision can be achieved. The experimental result shows the optimum parameters are aluminum dipping for 4 minutes, 450 V of micro-arc voltage for 20 minutes and 40 minutes of boiling water sealing, reaching 10.2 V of withstanding voltage. A further electrochemical drilling has been done to explore the effect of insulation. Two electrodes, with and without insulation had been compared. The difference between the entrance and the exit diameter of the hole of insulated tool reaches 17um, compare to the one without insulation, we have successfully reduced 81um. The result shows that the insulation has effectively reduced the stray effect, and achieve high precision machining.