Material removal mechanism in ultra-precision grinding of hard and brittle materials using small ball-end diamond grinding wheel

Small ball‐end fine-grained diamond grinding wheel offers notable advantages in the ultra-precision grinding of small complex curved-surface components, owing to their excellent machining flexibility and material removal capability. Reducing abrasive grain size is considered an effective strategy for achieving plastic-regime removal of hard and brittle materials while suppressing subsurface damage. However, the material removal mechanism during the machining of hard and brittle materials using small ball-end grinding wheels remains inadequately understood, thereby limiting their broader application in ultra-precision machining. In this study, fused silica, a representative hard and brittle material, was selected to investigate the influence of abrasive grain size on surface integrity and grinding characteristics. The results demonstrated that although the finer-grained grinding wheel produced excellent surface quality, it induced significant ploughing effects during grinding, which reduced material removal efficiency, accelerated grinding wheel wear, and increased grinding force. Furthermore, single-grain SPH scratching simulation and stress field analysis were conducted to clarify the subsurface damage evolution of fused silica under different abrasive grain sizes. Moreover, the damage mechanisms in both plastic-regime and brittle-regime removal modes when using small ball-end grinding wheels were revealed through TEM analysis. Finally, grinding experiments on typical small complex curved-surface components, hemispherical resonators, were performed to validate the feasibility of abrasive grain size modulation in practical machining. This study establishes a damage mechanism framework for grinding of hard and brittle materials using small ball-end grinding wheels, providing both theoretical and process guidance for low-damage precision machining of small complex curved-surface components.