Study on reverse copying precision of micro-electrode array fabricated by micro-EDM

Reverse copying precision of micro-electrode array fabricated by micro electrical discharge machining (micro-EDM), is explored and assessed in this article. The non-uniform electric-field intensity distribution and arc discharge are the two reasons that affect reverse copying precision greatly. First, in the reverse copying process for micro-electrode array fabrication, the charge is not evenly distributed in the workpiece and the flat electrode, so discharge is easy to happen in place of higher electric-field intensity and more material is eroded off. For the other reason of electric arc, because that the thicker rod electrode can't rotate and discharge gap is several microns level, working fluid is hard to flow inside discharge gap, throwing out process of debris and carbon deposition is further hampered by electrode array. Electric corrosion product is easily attached to the micro-electrode, in particular, easily attached to the electrode head has just been formed, resulting in electric arc and debris cumuli. Based on theoretic analysis, ultrasonic vibration is added on the plane plate electrode. Influence of ultrasonic vibration is analysed from the way of vibration mechanics through theoretical analysis and experimental observation. Compared with machining without ultrasonic vibration, better surface quality is achieved. Finally, 5×5 arrays of micro-electrode arrays are got, the diameter of single electrode is less than 30μm and height-to-width aspect ratio is more than 8, moreover these arrays of micro-electrode have very good surface quality.