A molecular dynamics study of the effect of impact velocity, particle size and angle of impact of abrasive grain in the Vibration Assisted Nano Impact-machining by Loose Abrasives

Vibration Assisted Nano Impact-machining by Loose Abrasives (VANILA) is a novel nanomachining process that combines the principles of vibration-assisted abrasive machining, and tip-based nanomachining, to perform target specific nanoabrasive machining of hard and brittle materials. An atomic force microscope (AFM) is used as a platform in this process wherein, nanoabrasives, injected in slurry between the workpiece and the vibrating AFM probe, impact the workpiece and cause nanoscale material removal. Molecular dynamic (MD) simulations are performed in this study to understand the effect of critical process parameters, viz. impact velocity, particle size, and the angle of impact of the abrasive grain on the material removal by the VANILA process. It was found that a higher impact velocity, larger abrasive size and higher angle of impact result in a larger amount of material removal from the workpiece. A material removal mechanism map capturing the effects of impact velocity and abrasive grain size on the occurrence and transitions between plasticity-dominated and fracture-dominated behaviors during VANILA process is made, which reveals different regimes of material removal mechanisms and their transitions. Confirmatory tests show that higher amount of material removal is observed in brittle mode machining with peak material removal occurring for high angle of impacts in the range of 60-90°. In ductile mode machining, relatively a lower amount of material removal is observed with the peak material removal occurring for low angle of impacts in the range of 15-30°.