The Effect of Electropolishing Time Variation at Room Temperature and Low Voltage on the Surface Quality of Cardiovascular Stent

Abstract

Electropolishing is an attractive method for surface smoothing of cardiovascular stent. This study investigated the effect of times of electropolishing on the surface characteristics both are upper surface and surface of the strut of cardiovascular stent after the by die sinking electrical discharge machining (EDM). The observed surface characteristics of the strut were recast layer, surface roughness and brightness. The weight analysis, and the reduction of the width strut were conducted. The recast layer was analyzed by optical microscope qualitatively, the surface roughness was measured by surface texture measuring instrument, the weight analysis and the reduction of width strut were calculated. The stent was made from steel AISI 316 L. The times which were used in the electropolishing were 3 minutes, 7 minutes, and 11 minutes. The experimental results show that the time for smoothing and brightening of stent at room temperature and low voltage 5 V is 7 minutes. The times affect the upper and EDM surface roughness, the weight of stent and the width of strut. The results show that increasing of times, than the value of surface roughness, the weight of stent and the width of strut will decrease, and vice versa. The average surface roughness of EDM surface after electropolishing is in the range of 3.49 – 1.62 µm. The average surface roughness of upper surface after electropolishing is in the range of 0.55-0.22 µm. The weight analysis show that the loss of weight is in the range of 0.12-1.12 %, and the reduction of width strut is in the range of 11.02 – 69.3 %.