Laser beam cutting and welding of coronary stents

摘要

Coronary stents are thin-walled and mesh-structuredudmetallic implants, which are made generally by laser beamudcutting of high-precision tubes of 90-120 micrometerudthickness. The tube material can be 316L stainless steel orudL605 type cobalt-chromium alloy. The paper present howudlaser settings influence geometry and surface quality of theudkerf and residual stresses, which play very important role inudthe precision of stent strut homogeneity.udHungarian Tentaur stent was developed 15 years ago. Thisudcoil stent made of 145 micrometers thick stainless steel wireudcontains 9-25 joints produced by electric resistanceudprojection welding. Developments were bringing out forudincreasing flexibility of Tentaur stent, and a new design anduda new tech-nology was elaborated, which’s based on laserudbeam mi-crowelding. TentaFlex stent also is constructedudfrom austenitic stainless steel wire, but it does not containudany wire-crossing joint, because stent struts are configuredudfrom sinusoidal helix. Stent contains only two welded jointsudat its ends. Laser welding experiences of these joints areudpresented in the paper. A Trumpf PowerWeld Nd:YAG laserudwork station was used for welding, and after optimization ofudlaser settings joints can’t produces from only one side of theudcoiled stent.