Theoretical and experimental investigation of material removal rate in magnetorheological shear thickening polishing of Ti-6Al-4V alloy

Abstract Magnetorheological shear thickening polishing (MRSTP) is a novel multi-field compound polishing method that combines the shear-thickening effect and the magnetorheological effect. It has great potential as an ultra-precise machining for complex surfaces. However, there is absence of the correlation between the material removal and the rheological properties of the polishing media leads to difficulties for further improvement in polishing efficiency and quality in MRSTP. In this paper, the material removal model for MRSTP was established based on magneto-hydrodynamics, non-Newtonian fluid kinematics and microscopic contact mechanics. It combines the material removal model for single abrasive and statistical model of active abrasives. On comparing the experimental and theoretical results, it showed that the developed material removal model can accurately predict the material removal depth of the workpiece under different processing parameters (rotational speed of rotary table and magnetic field strength). The average prediction error was less than 5.0%. In addition, the analysis of the rheological behavior and fluid dynamic pressure of the polishing media reveals the coupling effect 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 obtained on the cylindrical surface of the Ti-6Al-4V workpiece using the MRSTP method. The result shows that the MRSTP method has great potential in the field of ultra-precision machining of difficult-to-machine materials.