Nitinol is a nickel- titanium metal alloy that has a unique combination of properties that make it an attractive material for medical devices. These properties include shape memory effect and superelasticity.
Nitinol can remember its original, undeformed shape when subjected to deformation at a certain temperature, and return to that shape when heated above its "transformation temperature". Its elasticity under stress allows it to undergo large deformations (up to 30 times) before returning to its initial, unchanged state.
In medical applications, Nitinol is primarily used to make self-expanding stents for peripheral vascular and heart disease applications. Unlike stainless steel, which is highly susceptible to kinks in blood flow, these stents are kink resistant and torquable, making them a good choice for the tortuous vessel pathways of peripheral arteries.
Stents are a staple in the medical world and are used in a wide range of applications, including coronary, renal, pulmonary, and venous stenting. In these applications, the fatigue life of a stent is critical and the materials that are most suitable depend on factors such as chemical composition, inclusion size, and thermomechanical processing.
Several types of Nitinol can be used to make catheters and guidewires. Laser cutting is a common way to make stents in tubing form, while electrical discharge machining is also an option for sheet.
A key part of producing a high quality, reliable stent is the concentricity control and surface finish of the tube inner diameter. This is a key factor in determining the material's performance and maximizing yields.