Machining characteristics on electrochemical finish combined with micro EDM using deionized water

Fine surface finish of micro features processed by micro EDM is difficult due to small feature size. In this work, we investigated electrochemical finishing process after micro EDM. The product shape was machined by micro EDM, and the surface was finished by electrochemical process. For both processes, deionized water was only used as dielectric fluid for EDM and electrolyte for finishing. Surface formation characteristics during finishing and side gap increase were analyzed according to machining conditions. In addition, surface roughness and hardness were measured to compare three cases of surface processed by micro EDM in deionized water, by micro EDM in kerosene, and by finishing in deionized water after micro EDM, respectively. Micro grooves and pockets were fabricated by micro EDM milling and electrochemical finish. In the case of drilling, electrochemical finish in deionized water not only finished inner surface of the holes but also expanded entrance and exit hole size. Using this phenomenon, micro drawing die was fabricated by controlling finishing conditions.