Development and application of a fine-finish power supply in wire-EDM

A new fine-finish power supply has been developed to provide the functions of anti-electrolysis, high-frequency and low-energy pulse control. Through the quantitative analysis based on the experimental plan of Taguchi quality design, surface roughness is mainly affected by the pulse on-time of negative polarity and current-limiting resistance. An increase of the pulse on-time of negative polarity leads to an increase of surface roughness, while an increase of current-limiting resistance contributes to a decrease of surface roughness. Experimental results not only verify the usefulness of the developed fine finish power supply in eliminating titanium's bluing and rusting effect and reducing micro-cracking in tungsten carbide caused by electrolysis and oxidation, they also demonstrate that the developed system can achieve a fine surface finish as low as 0.22 mu m R-a.