Ultra-precision machining process of inner surface considering shear-thickening polishing method

Shear-thickening polishing (STP) is a non-traditional flexible ultra-precision processing method that exploits the polishing fluid’s shear-thickening properties to create a shear rate between the workpiece surface and the potential flow. This increases viscosity and achieves material removal. In the past, the shear-thickening polishing method was mostly employed for the outer surface of rotating bodies. Nevertheless, to apply the STP method to ultra-precision processing of the workpiece’s inner surface, this paper proposes an active formed shear-thickening layer polishing method based on a numerical calculation model. Additionally, the main parameters affecting the machining efficiency were identified, orthogonal experiments were performed on the process parameter levels, and optimal machining conditions were derived. The optimized process was adopted to machine the inner surface of the large-size bearing ring, and the surface roughness in terms of Ra was reduced from the original 131.27 to 27.14 nm in 30 min and further to 19.52 nm in 60 min. The validation experiments highlight that the numerical model can predict the experimental results accurately, demonstrating the proposed method’s feasibility for ultra-precision machining on the inner surface with the STP method.