Material removal characteristics of magnetic-field enhanced shear thickening polishing technology

To achieve the efficient and high-quality machining of hard and brittle ceramics used in various industries, in addition to other materials that are difficult to process, a magnetic-field enhanced shear thickening polishing technology was developed in this study. Based on the coupling effect of the magnetization enhancement and shear thickening, the proposed processing technology can improve the rheological properties of the shear thickening fluid, thus realizing an adaptive and efficient removal of microscopic materials. Herein, the microscopic material removal mechanism of this technology was analysed and the rheological properties of a magnetic shear thickening polishing fluid were studied. Based on the Preston's equation, the dynamic pressure of non-Newtonian fluids and the magnetorheological polishing theory, a material removal rate prediction model was established and it had a maximum relative error of 7.56%. The influences of the polishing head rotational speed, abrasive particle concentration and carbonyl iron powder particle concentration on the material removal function were investigated and the stability of the prediction model was verified. After polishing a zirconia workpiece for 20 min, a low-damage machining surface was obtained and the surface roughness was 8.3 nm. Therefore, the effectiveness of the material removal prediction model was verified and the findings of this study provide a theoretical basis for the realization of deterministic polishing. Moreover, the feasibility of the magnetic-field enhanced shear thickening polishing method for the ultra-precision machining of hard-to-machine materials, such as hard and brittle ceramics, was verified.