Crack-deflection controlled 3D EVC of silicon for large-DOC high-quality machining

To overcome the trade-off between efficiency and quality in the precision cutting of monocrystalline silicon, this study investigates the influence of 3D elliptical vibration cutting (3D EVC) process parameters on its material removal characteristics. Through a combination of comparative experiments and finite element method (FEM) simulations, the effects of cutting speed, vibration amplitude, phase shift, and tool orientation (oblique angle) on the ductile-to-brittle transition (DBT) and the distribution of maximum principal tensile stress (MPTS) in monocrystalline silicon were systematically investigated. It is found that active control of the tool posture and position enables 3D EVC to generate a unique spatial trajectory, which significantly alters the stress field in the tool-workpiece interaction zone and achieves a directional bias of brittle defects. Based on this mechanism, a high-efficiency and low-damage machining strategy is proposed to ensure superior surface quality even at depths of cut (DOC) exceeding the critical DBT value. Experimental results on monocrystalline silicon demonstrate that at a DOC of 3.03 μm, a high-quality planar surface with a roughness Sa of 44.76 nm was successfully achieved, verifying the significant advantages of 3D EVC in the high-performance manufacturing of hard-brittle materials. The findings offer valuable technical insights for optimizing the advanced fabrication of difficult-to-machine brittle substrates.