Additive manufacturing of cardiovascular CoCr stents by selective laser melting

In this work, the selective laser melting (SLM) of CoCr alloy powder for producing cardiovascular stents is investigated. The paper aims to assess the feasibility of producing a CoCr stent precursor through SLM as an alternative method to the conventional manufacturing cycle, which is based on microtube production and consecutive laser microcutting. Design rules for manufacturability are investigated, and a simple prototype design for additive manufacturing is proposed. The SLM process is investigated with an industrial system that utilises pulsed wave emission. Different scan strategies, namely hatching and concentric scanning, were used. Strut thickness and roughness, as well as chemical composition, were analysed. Representative conditions were further analysed by microhardness measurements and X-ray micro computed tomography. Electrochemical polishing was applied to assess the feasibility of surface finishing. The results show that SLM can be considered as a substitute operation to microtube manufacturing and laser microcutting for shaping precursors in stent manufacturing. Prototype stents with acceptable geometrical accuracy were achieved and surface quality could be improved through electrochemical polishing. The chemical composition remained unvaried, with a marginal increase in the oxide content.