Study On Magnetorheological Polishing Technology For 316L Stainless Steel Formed By SLM

Selective Laser Melting(SLM)is one of the additive metal manufacturing technology which can be used to manufacture part with complex shape that are difficult to be achieved by traditional machining.But the surface formed by SLM exist flaw such as the step effect,balling effect,powder adhesive effect and so on.In order to satisfy the increasingly strict requirement of surface quality,many non-traditional surface machining techniques have emerged include magnetorheological polishing.In this paper,magnetorheological polishing equipment,track of polishing,and magnetorheological polishing fluid has been studied.Analysis and conclude the effect of polishing parameter on surface quality through a large number of comparison polishing experiments.Conclusions are as follow:1.Two kinds polishing tools were designed and manufactured,and working magnetic field has been optimized as well.Duo-track-cluster magnetorheological polishing device's magnetic field becomes uniform and the average magnetic induction intensity is up to 0.857 T when the arrangement of magnetic poles use a longitudinal staggered way analyzed by Maxwell.For the matrix-cluster magnetorheological polishing device,the magnetic field becomes uniform when the magnetic poles are staggered,and the peak magnetic induction intensity reaches 1.2T.2.The trajectory equation of single abrasive particles was established and the polishing path was planned.For duo-track-cluster magnetorheological polishing,the linear polishing is planned.When the spindle speed is 1000r/min and the working feed is 0.2mm/min,the optimal path is obtained.For matrix-cluster magnetorheological polishing,the offset polishing is planned,and the optimal path is when the speed ratio is 80,the offset distance is 20 mm,the yaw amplitude is 8mm,and the yaw angle is 45°.3.The properties of magnetorheological polishing fluid were prepared and studied.Oil-based MR polishing fluid with carbonyl iron powder as magnetic particles and brown corundum powder as abrasive particles were prepared and their rheological properties were studied.The following conclusions: with the increase of magnetic field intensity,the concentration of carbonyl iron powder and brown corundum powder,viscosity and shear stress are increase.With the increase of temperature,the viscosity and shear stress gradually decrease and tend to be gentle.With the increase of the shear rate,the viscosity decreases,but the shear stress increases.4.Study on the polishing process by the polishing tool of duo-track-cluster structure.The conclusions are as follows: For surface roughness,prolonging the polishing time can improve the surface roughness,while with the increase of gap,rotate,feed,abrasive particle and magnetic particle concentration,the surface roughness decreases first and then increases.For residual stress,which is increased with the polishing time,feed,abrasive particle and magnetic particle concentration,while with the increase of polishing gap and rotate,the residual stress decreases.When the time is 180 min,the gap is 0.6mm,the rotate is 600r/min,and the feed is0.8mm/min,the polishing effect is the best.5.Study on the polishing process of specimen by the polishing tool of matrix-cluster structure.The conclusions are as follows: For surface roughness,with the increase of polishing time,the surface roughness decreases gradually,while with the increase of gap,rotate and feed,the surface roughness decreases first and then increases.For residual stress,with the increase of polishing time,gap,rotate and feed,the residual stress gradually decreases.When the time is 240 min,the gap is 1.0mm,the rotate is 400r/min,and the feed is 9mm/min,the polishing effect is optimal.In summary,duo-track-cluster magnetorheological polishing has the advantages of high efficiency and less polishing medium consumption,and it is suitable for small size thin-walled parts.Matrix-cluster magnetorheological polishing has the advantages of high precision and easy storage of polishing media,and it is suitable for large area plane parts.These two polishing forms of 316 L stainless steel polishing is a new attempt.