Fast-tool-servo-controlled shear-thickening micropolishing

Polishing-based post-processing is essential for removing the undesired surface diffraction on diamond-turned microstructured surfaces that is enhanced by periodic tool marks. To overcome challenges in existing micropolishing methods, a fast-tool-servo-controlled shear-thickening micropolishing method was proposed for the non-contact and controllable polishing of microstructured surfaces. The operating kinematics and material removal mechanism are modeled analytically and investigated experimentally. The comprehensive principal stress in front of the rake face of the tool is found to mainly contribute to the material removal. The fast tool servo can tune the principal stress and the viscosity of the slurry by flexibly adjusting the gap width between the surface and the tool edge. Thus, the material removal can be controlled at any operating position. Meanwhile, although the material removal rate is nonlinearly related to the rotation radius and gap width, the constraint between these two factors is linear for achieving a fixed material removal rate. Finally, the feasibility of the proposed micropolishing method is demonstrated by successfully polishing rotationally symmetric and asymmetric microstructured surfaces to achieve improved surface smoothness and conformal surface shapes. • Fast tool servo-controlled micropolishing strategy was proposed for finishing microstructured surfaces with high shape conformality. • Material removal happens in front of the rake face of the tool. • Fast tool servo can adjust the stress and slurry viscosity for micropolishing by controlling the gap width. • Constant material removal rate leads to a linear constraint between the gap width and the rotational radius.