S. Mueller, S. Gall, R. Nitschke, F. Gensch
FORMING GmbH,
Germany
Keywords: magnesium, biodegradable, stent, microtube
Summary:
High-precision microtubes are the starting material for the production of stents. Stents made of magnesium alloys are an interesting alternative to conventional stents made of cobalt-chromium or cobalt-nickel alloys, as these stents are biodegradable and therefore do not remain permanently in the body. Like other stents, magnesium-alloy stents must have sufficient mechanical strength and very good elongation at break in order to withstand the pressure in the vessel on the one hand and the plastic deformation during crimping and delamination on the other. Due to the hexagonal lattice structure and the previous manufacturing method, the high elongation at break in particular posed a major challenge in the production of magnesium stents. Thanks to the new production method developed by the Extrusion Research Center at TU Berlin and FORMING GmbH, in which the microtubes are extruded directly to their final dimensions, elongation at break of over 20% could be achieved with high strength at the same time. Thanks to innovative process control, the same tight tolerances could be achieved as with drawn microtubes. In addition, the production process is significantly more cost-effective due to the elimination of deep-hole drilling and multi-stage tube drawing.