Plastic abrasive jet machining(PAJM)is an advanced material-reduced processing technology.It is a new technology developed by using thermosetting plastic abrasives instead of traditional hard abrasives,which could effectively remove surface coatings without damaging the substrate.The lossless substrate is obtained by controlling the erosion stress of the plastic abrasive on the substrate,the erosion stress of the plastic abrasives should be less than the ultimate strength of the substrate fibers or the bonding strength between the fibers and the resin.Theoretical analysis,computational fluid dynamics simulation and experiments of particle velocities were carried out using a combination of finite element simulation and experiments.The particle velocities under different gas pressures were investigated,and the calculated results were in good agreement with the experimental data.The results show that as the abrasive particles leave the nozzle,the particle velocity increases within 6.2 dN(dN is the inner diameter of the nozzle)from the nozzle outlet;on the contrary,the particle velocity gradually decreases outside 6.2 dN from the nozzle outlet.When the abrasive particle size changes from 20-30 mesh to 40-50 mesh,the maximum particle velocity increases from 164.365 m/s to 228.402 m/s.As the abrasive particle size decreases,the particle velocity increases and the angle of divergence increases.In comparison,the numerical modeling provides a better prediction of particle velocity and distribution of plastic abrasives.This study highlights the effects of the control of the particle size and standoff distance on the particle velocity and angle of divergence in the jet field.It provides a theoretical reference for controlling the erosion stress of particles on the substrate and avoiding substrate damage.
Air Jet MachiningPlastic AbrasiveParticle VelocityFinite Element SimulationNumerical Simulation
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