Theoretical and Experimental Investigation of Material Removal Rate in Magnetorheological Shear Thickening Polishing of Ti–6Al–4V Alloy

Magnetorheological shear thickening polishing (MRSTP) is a novel hybrid polishing method that combines the magnetorheological effect and the shear thickening effect. It has great potential for ultra-precision machining of complex surfaces. However, the absence of a correlation between material removal and the rheological properties of the polishing media has posed difficulties for further improvements in polishing efficiency and quality in MRSTP. In this work, a material removal model for MRSTP was established based on the principles of magneto-hydrodynamics, non-Newtonian fluid kinematics, and microscopic contact mechanics. This model combines the material removal model for a single abrasive particle with a statistical model of active grits. When comparing the experimental and theoretical results, it became evident that the developed material removal model can accurately predict the material removal depth of the workpiece under different processing parameters such as rotational speed of the rotary table and magnetic field strength. The average prediction error was found to be less than 5.0%. Furthermore, the analysis of the rheological behavior and fluid dynamic pressure of the polishing media reveals the coupling effects between the magnetic, stress, and flow fields. This provides theoretical guidance for the actual processing of MRSTP. Finally, the maximum material removal rate of 3.3 μm/h was achieved on the cylindrical surface of the Ti–6Al–4V workpiece using the MRSTP method. These results demonstrate that the MRSTP method holds great potential in the field of ultra-precision machining of difficult-to-machine materials.