A process chain study for manufacturing nitinol stents

Abstract

Nitinol is a commonly used alloy for manufacturing medical devices (i.e., stents). This study examines the process chain for manufacturing nitinol stents, focusing on the effects of laser cutting, heat treatment, and electropolishing processes on the stent’s final surface roughness, strut thickness, weight, and recoil. The laser cutting’s experimental results showed an optimal surface roughness (Ra) under 1.20 μm at 65% and 95% spot overlap, corresponding to feed rates of 300 mm/min and 749 mm/min, respectively. Heat treatment experiments on expanded stent samples revealed the lowest recoil of 0.78 mm achieved at 550°C for 720 s for 0.2 mm strut thickness. Electropolishing using 18V for 20 s provided the greatest reduction in surface roughness (Ra and Rz), along with a decrease in the weight and wall thickness. The results highlight the importance of optimizing process parameters to obtain desired surface quality, shape setting, and dimensional characteristics for functional nitinol stents. The research provides insights into enhancing the manufacturing of self-expanding nitinol stents for improved clinical outcomes.