Experimental investigations into belt-type magnetorheological finishing of exterior surfaces

In recent years, the demand for high-precision components with high-quality surfaces produced by ultra-precision techniques grows rapidly across various industries. The in-house designed and developed Belt Type Magnetorheological Finishing setup achieves nanometer-level finishing on large external surfaces such as flat, convex, cylindrical, and spherical surfaces etc. by utilizing the flexible compliance of magnetorheological polishing fluid. Different electromagnet configurations are analyzed through magnetic simulations, and an H-shaped arrangement of three electromagnets is selected for the developed setup. The magnetorheological fluid is prepared by mixing Electrolytic Iron Particles (EIPs) and SiC abrasives in a viscoplastic carrier medium. The process is first analyzed on flat brass samples using Response Surface Methodology to determine the optimum fluid composition. The optimized mixture contains 22.85% abrasives and 26.95% EIPs by volume. Using this optimized composition, the finishing capability of the setup is further evaluated on convex samples. Under these conditions, the surface roughness of flat samples reduces from 58.6 nm to 18.13 nm, while for convex samples it decreases from 341 nm to 170 nm within 40 minutes of finishing. Surface topographies have been analyzed using SEM and a stereo microscope, revealing defect-free surfaces without noticeable scratches.