Computer-aided process planning system for super finishing of flat surfaces with pockets through magnetorheological finishing process

Magnetorheological Finishing (MRF) process is an advanced surface finishing operation that provides mirror-like polished surfaces required for the implants, lenses (telescope, microscope, etc.), miniature parts, etc. for their enhanced functionality. However, various features (including holes and pockets) on the workpiece surface produce a challenge during their polishing through the MRF process; the Carbonyl Iron Particles (CIPs) chains get trapped inside the holes during the finishing operation and generate irregular surface quality on the polished surface. This paper outlines a Feature-based Hybrid MRF Planning System (FHMRF-PS) developed on the geometrical data inputs to produce automated process planning for the paraffin wax deposition into the hole and pocket features of the workpiece before MRF. An external module is developed to deposit paraffin wax in the holes and pockets to ensure a uniform finish over the targeted surface. Herein, appropriate toolpath strategies are included for the deposition and MRF process to enhance finishing efficiency. Furthermore, a case study on a bone plate made of Ti-6Al-4 V is performed to analyze the efficiency and effectiveness of the developed FHMRF-PS. The initial surface roughness (R-a) value of 324.12 nm is reduced to 21.56 nm after the proposed process planning during MRF. The impact of underfilling and overfilling of paraffin wax on the surface quality of the polished surface is also analyzed in the present study. Further, the uniformity of the surface roughness over the MRF polished surface is compared with and without paraffin wax deposition inside the workpiece's hole and pocket features. It is found that paraffin wax deposition helps to produce uniform surface quality.