Investigation and process optimization for magnetic abrasive finishing additive manufacturing samples with different forming angles

The staircase effect, balling effect, and powder adhesion as well as other problems in additive manufacturing (AM) forming all lead to the poor uniformity and high roughness of the sample surfaces. Therefore, there exist differences in the physical and mechanical properties of the samples. In this paper, the spherical composite magnetic abrasive particles (MAPs) are used for magnetic abrasive finishing (MAF) experimental investigations and process optimization of the AM sample surface. According to the Box-Behnken design principle of the response surface methodology, the finishing effects of different process parameters (spindle speed, feed speed, and machining gap) of MAF on the samples prepared by selective laser melting (SLM) with different formed angles are studied, the quadratic regression equations are established, and the validity of the equations are assessed by ANOVA and 3D response surfaces. After that, MAPs with smaller size were selected for the fine MAF experiments with the optimized parameters. Finally, we found that the optimal parameters of MAF for the same material with different forming angles are similar, but the polishing time consumed is quite different. After the MAF experiments, the changes of the surface Vickers hardness, roughness (Ra), and microscopic morphology are analyzed. The surface roughness of each sample is reduced from the initial 4–10 μm to about 100 nm, and the diversities in hardness are also reduced. MAF significantly improves the defects of poor surface uniformity caused by inconsistent forming angles.