Bio-inspired design of a 3D-printed flexible polishing tool: Structural compliance and material removal mechanisms for K9 glass

To mitigate interface closure, pressure concentration, and slurry starvation in the precision finishing of hard-brittle optics, a novel flexible polishing tool featuring a plant-root topology was designed and fabricated via stereolithography 3D printing. Incorporating hierarchical branching and continuous curvature turning, a 3D labyrinthine micro-circulation network comprising mixing, transport, and textured polishing zones was integrated into the tool. A cross-scale theoretical model coupling a modified Preston equation with elastoplastic matrix deformation and multiphase dynamics was developed to clarify the material removal mechanisms. FEA and CFD simulations demonstrated that the internal channels proactively modulate localized structural compliance—transforming the quasi-Gaussian peak stress into a flattened multi-modal profile—while alleviating core zone slurry starvation via a deformation driven pumping mechanism. Fixed point polishing experiments on K9 glass validated that the bio-inspired tool improved contact pressure homogeneity by 40.22 %, yielding a rapid surface roughness convergence from Ra 2.60 μm to 0.241 μm within 10 min, and ultimately achieved a precision finish of Ra 0.090 μm. This study provides a scientifically viable structural paradigm for high efficiency, green processing of hard-brittle materials.