Effect of pulse current in manufacturing of cardiovascular stent using EDM die-sinking

This paper proves that die-sinking electrical discharge machining (EDM) is an alternative and attractive manufacturing method of producing cardiovascular stent. This study investigates the effect of pulse currents on the material removal rate (MRR), the surface of EDM, and the upper surface of the strut stent. The observed surface characteristics of the strut were surface roughness, recast layer, and the diameter of the crater. The recast layer and crater were analyzed by an optical microscope, and the surface roughness was measured by a surface profilometer. The pulse currents which were used in the manufacturing of stent by die-sinking EDM were 1.5 A/45 mu s, 3.0 A/90 mu s, 4.5 A/120 mu s, and 6 A/150 mu s. The experiment shows that the stent is successfully manufactured from minitube AISI 316L by die-sinking EDM. The diameter, length, and thickness of the stent are 4 mm, 20 mm, and 0.3 mm, respectively. The results show that increasing of pulse current will cause the increase of MRR, the thickness of recast layer, the surface roughness, and the crater diameter. The MRR, thickness of the recast layer, surface roughness, and crater diameter are also influenced by the pulse on time. The EDM surface roughness, the average thickness of recast layer, and the diameter of crater are in the range of 3.49-9.53 mu m, 17.6-97 mu m, and 75.84-276.5 mu m, respectively, and the upper surface roughness of the strut is 0.5534 mu m. The best quality of the strut is generated from the pulse current 1.5 A/45 mu s.