Modeling of material removal by magnetic abrasive finishing of the inner wall of Co-Cr alloy cardiovascular stent tube with diamond magnetic abrasive powder prepared by plasma melting

This study describes the application of a magnetic abrasive finishing process (MAF) to the inner wall of the Co-Cr alloy cardiovascular tube to obtain a fine surface roughness and improve the surface quality. The high-performance spherical iron-based diamond magnetic abrasive powder (MAP) used in the experiments was prepared via combining plasma molten metal powder with sprayed abrasive powder. The experiments were carried out on a MAF machining machine for slender tubes, with permanent slotted magnets as the magnetic field-generating device. The processing mechanism of the MAF on the inner wall of the tube was analyzed, and the magnitude and distribution of the magnetic flux in the processed area were simulated by software. The material removal model for MAF processing of the inner wall of the tube was constructed from mechanical properties of magnetic abrasives and the workpiece and five applied process parameters: finishing time, tube rotational speed, magnetic feed rate, size of MAPs, and filling quantity of MAPs. Single-factor experiments were designed and carried out using surface roughness Ra and quality differences before and after MAF processing as evaluation indicators. The results were used to analyze the relationship between five process parameters and surface roughness Ra and material removal MR. Scanning electron microscopy was used to observe the effect of the MAF process on the surface quality. It shows that the MAF process can effectively remove the defective layer from the workpiece and improve its surface smoothness and quality. The surface roughness Ra of 0.46–0.49 μm before finishing was decreased to 0.093 μm with optimal process parameters.