Experiment Research of Polishing Capability of Magnetorheological Finishing with a Small Permanent Magnet Ball-End Tool

In order to resolve the difficulty in polishing work of complex shape, a new magnetorheological finishing (MRF) technology with a small permanent magnet ball-end tool is developed. Rotary symmetrical magnetic field generated by the small permanent ball-end tool, stiffen a magnetic fluid which is delivered by a slender needle tubing, in contact with a workpiece. The permanent magnet tool is hold by a slender cylindrical shank, so it won’t interfere with workpiece when polishing deep concave cavity. A prototype apparatus is established to study the processing characteristics of this polishing method. MRF spots are taken on stationary workpiece to study the influence of several processing parameters on the material removal function, such as, spindle speed, included angle and minimum gap between polishing tool and finishing-surface. A 3×3mm square on a fused quartz (FS) is polished and the surface roughness decrease from 81nm Ra to 1.5nm Ra after polishing for 100min.