This week I enjoyed the excitement and frustration of shape setting Nitinol tubing for a prototype medical device used for a demonstration. I obtained samples from NDC and Memry . Both provided free samples within days. Nitinol is commonly used in medical devices because of its superelastic or shape-memory characteristics. In my application, I am taking advantage of the superelastic properties.
Shape setting Nitinol is a quick and easy process provided you have the appropriate equipment. To shape set the Nitinol, I created a fixture to securely hold the Nitinol to the desired shape. I then pre-heated an oven to 500-550°C. Next, I placed the part in the oven for 1 minute. I then removed the part and immediately quenched it in water. If you overheat the part it will reduce its superelastic properties.
The key to designing parts with Nitinol is to obtain material and start testing as soon as possible. Nitinol is NOT an easy material to design with because it does not have a linear stress-strain curve like stainless steels. Hence, most design formulas are not applicable. This week I learned that even though think-walled Nitinol tubes are flexible, they will splinter when compressed axially.
By Margaret Koga
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About PADT Medical
PADT Medical specialize in helping entrepreneurs achieve early and critical milestones in the development of complex mechanical and electromechanical systems used in orthopedic, cardiovascular, and endoscopic applications. From concept design through clinical trials, we provide startups with an instant and flexible R&D team with the experience and resources to accelerate:
•Product Design
•Clinical-Use Prototypes
•Verification Testing
•Regulatory Compliance
•Product Design
•Clinical-Use Prototypes
•Verification Testing
•Regulatory Compliance