Material removal mechanisms in hybrid fixed-loose abrasive machining of SiC

In ultra-precision hybrid abrasive machining of single-crystal silicon carbide (SiC) using fixed and loose diamond abrasives, the complex interactions between abrasives and workpiece render the material removal mechanisms insufficiently understood. To address this limitation, molecular dynamics (MD) simulations were employed to investigate the coupled motion behavior of the abrasives and the corresponding material removal process. The results show that material removal is dominated by cutting and plowing, driven by the sliding motion of the fixed abrasive. Conversely, the loose abrasive contributes primarily through rolling, which improves surface quality by compressing displaced atoms back into the machined surface. Increasing the cutting depth and transverse spacing enlarges the contact area between the abrasives and the workpiece, while promoting a partial transition from rolling to sliding in the loose abrasive motion, thereby enhancing material removal efficiency. However, an elevated cutting depth also intensifies the friction force, internal stress, and temperature, aggravating subsurface damage (SSD) and phase transformation. In addition, excessive cutting depths and transverse spacings weaken the compaction effect induced by the rolling of the loose abrasive, thereby limiting surface roughness reduction. By regulating the cutting depth and transverse spacing, both material removal rate (MRR) and surface quality can be improved. These findings clarify the mechanisms by which abrasive motion governs material removal and provide a framework for optimizing the hybrid abrasive machining of hard and brittle materials.