The water-solution type coolant is used instead of ordinary. oil type coolant and the effect of the coolant on the finishing is investigated experimentally. As work materials, titanium, titanium alloies and Ni-based alloy are used. Electrolytic in-process dressing is employed to promote the ability of metal removal because the water-solution type coolant is inferior to that of oil type one in the permeability. The specific cutting energy k s of these materials are compared with k s of a bearing steel in order to evaluate the machinability of the work materials. The results obtained are as follows. The superfinishing opera-tion using a water-solution type coolant is the effective method to finish the surface of these difficult-to-cut materials when the electrolytic in-process dressing is applied together. The suitable conditions in electrolytic dressing for each work material are obtained, and the titanium which has the highest adhesive property needs the strongest electrolysis among the work materials used in this study. The electrolytic-in-process dressing makes it possible to maintain the cutting ability of the finer grain size stone for a long time, and to obtain the mirror surface of Incoloy 800 with #8000 SD diamond stone.
