Modeling and experimental study of polishing forces in magnetorheological polishing of thin-walled 304 stainless steel parts

Thin-walled 304 stainless steel components are widely used in precision manufacturing due to their excellent properties; however, their low stiffness makes them highly susceptible to deformation during conventional polishing, which can be difficult to control and limit dimensional accuracy and surface quality. To address this issue, this study aims to establish a mechanical model capable of accurately predicting the normal and shear forces during magnetorheological polishing (MRP). A normal-force model incorporating magnetic levitation, hydrostatic pressure, centrifugal force, and the resultant gravity and buoyancy forces was established, and a shear-force model was developed based on the Herschel–Bulkley constitutive equation. A novel thin-walled effect correction mechanism was introduced by coupling the normal force with the workpiece’s elastic deflection, thereby correcting the actual machining clearance and improving the model’s predictive accuracy for flexible workpieces. An experimental platform for polishing force testing was constructed, and experimental validation was conducted under varying conditions of carbonyl iron powder concentration (55%–85%), abrasive concentration (5%–20%), machining clearance (1.2–2.1 mm), and rotational speed (300–600 rpm). The results indicate that the trends of the model-calculated and experimentally measured values are highly consistent, with the maximum relative error controlled at 13%. The modified model proposed in this paper effectively describes the dynamic mechanical behavior during MRP of thin-walled parts, providing a theoretical basis for precise, quantitative machining.