Micro-EDM of Cemented Carbide Alloys

Abstract

This paper consists of two parts. One contains experimental results about micro-drilling of cemented carbide alloys by EDM, leading to industrial application. The other is theoretical analysis of the wear ratio, characteristic in EDM performed by very low energy pulses (<3μJ/pulse).The results are as follows.1. Micro-holes with diameters of 6μm and 9μm were drilled to cemented carbide alloy of 50μm thick by EDM.Rectangular micro-holes (approximately 40μm×45μm) were machined to the same workpiece by EDM. It takes only 10-15sec. for each of them.2. The erosion ratio, (cathode erosion)/(anode erosion), extremely decreases as the energy of each one pulse decreases, independently of materials of electrodes. For example, the ratio is some 10% in most materials when the capacity of condenser is 500pF and the charging voltage is 100V.3. The cause of the fact mentioned above has been explained with T-F theory and Mackeown's Formula, as a result lead from the increase of je/j, where je is current density by electrons and j is the total current density.