Abrasive Impact Behavior and Local Material Removal Mechanism in Magnetic Liquid Metal Assisted Polishing of Complex Curved Surfaces

During abrasive flow polishing of complex curved surfaces, local concave and curvature transition regions often suffer from insufficient near-wall abrasive transport and reduced impact frequency, resulting in non-uniform material removal in weak-flow regions. To address this issue, this study proposes a magnetic liquid metal particle-mediated abrasive flow polishing mechanism for complex curved surfaces. Models of near-wall abrasive impact response, coupled collision between magnetic liquid metal particles and abrasives, and local material removal were established and validated through explicit dynamic simulations and polishing experiments on Ti–6Al–4V complex curved surfaces. The single SiC abrasive impact results show that abrasive radius, initial velocity, and incident angle jointly determine the local stress response of the workpiece surface. Within the investigated range, an abrasive radius of 7.5 μm, an initial velocity of 5 m/s, and an incident angle of 60° produced a balanced stress concentration and affected area. Coupled collision results indicate that abrasive impact is not monotonically enhanced by increasing particle diameter or initial velocity. A magnetic liquid metal particle diameter of 200 μm and an initial velocity of 3 m/s generated the highest instantaneous equivalent stress and a concentrated high-stress distribution on the protrusion surface, indicating favorable momentum transfer and local energy concentration. Polishing experiments show that magnetic-field-assisted magnetic liquid metal abrasive flow polishing markedly weakened residual grooves in weak-flow regions and improved regional surface quality consistency. After 12 h of polishing, the regional roughness difference ΔSa decreased from 114.15 nm without magnetic field assistance to 30.69 nm with magnetic field assistance, corresponding to a reduction of 73.11%. These results demonstrate that magnetic liquid metal particles enhance local material removal in weak-flow regions through near-wall enrichment and collisional momentum transfer.