Nanofinishing of flat workpieces using rotational-magnetorheological abrasive flow finishing (R-MRAFF) process

A new finishing process named as "rotational-magnetorheological abrasive flow finishing (R-MRAFF)" has been proposed to enhance the finishing performance of MRAFF process. In this process, a rotation cum reciprocating motion is provided to the polishing medium by a rotating magnetic field and hydraulic unit. By intelligently controlling these two motions, a uniform smooth mirror-like finished surface with improved material removal rate and finishing rate (nanometer per cycle) is achieved for both stainless steel and brass workpieces. From the preliminary experiments, it is found that R-MRAFF process produces better results than MRAFF. Experiments have been planned using design of experiments technique. Analysis of variance is conducted to find out the contribution of each model term affecting percent improvement in surface finish. The optimum finishing conditions are identified from optimization study. The present study shows that the combinations of rotational speed of the magnet and its square term together have the highest contribution to the percentage improvement in surface roughness. Other significant parameters in the order of decreasing percent contribution to the change in surface roughness value are finishing cycles, extrusion pressure, and fluid composition. The best surface finish obtained on stainless steel and brass workpieces with R-MRAFF process are 110 and 50 nm, respectively. From the scanning electron micrographs and atomic force micrographs, it has been observed that the abrasive cutting marks generate cross-hatch pattern on the surface finished by R-MRAFF process.