Study of surface finishing mechanism in a rotational-magnetorheological miniature gear profile polishing using novel flow restrictor

Nano-finishing of miniature gear is a tough job since its geometry is complex. Traditional gear finishing methods can cause burns, micro-cracks, scratch marks, burrs, pits and thermal distortion in gear teeth profiles. Because of the limited spacing between the gear teeth, miniature gears can only be finished with a few processes. This article reports on the new uniform flow restrictor used in the rotational magnetorheological fluid-based finishing (RMRFF) method to ensure a consistent and precise polishing of gear profiles. The uniform flow restrictor is analyzed using a commercial software program (COMSOL (R) Multiphysics) focused on finite element analysis (FEA). The surface roughness simulation is also performed using the results of the FEA and force analysis on active abrasives. The simulated roughness values are consistent with experimental values. Later, the experiments are performed without and with a novel uniform flow restrictor on the SS316L spur gear teeth profile to examine and compare the finishing performance. After finishing the gear, the minimum surface roughness of Ra = 23.9 nm at the tooth profile is achieved, and further, all manufacturing defects are entirely removed. Concurrently, the teeth geometry profiles are not affected. The uniform finishing of miniature gear with a continuous smooth surface may improve its work performance, transmitting power ability, reliability, fatigue life and form accuracy.