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Forget what you know about metals behavior
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If you've seen nickel titanium, you know the response: "Wow."
NiTi is temperature-activated. When cooled it becomes pliable, to be formed as you wish. Upon returning to its warm, resilient state, it "remembers" its programmed shape and returns to it - applying force against anything it its way.
Nickel titanium is more than resilient. It's lightweight, non-corrosive, biocompatible, wear resistant and more. Engineers specify nickel titanium for two qualities: shape memory and super-elasticity.
Super-elasticity describes the material's ability to recover from large amounts of strain. A NiTi component can fully recover from strain values up to 8%. (Stainless steel, by comparison, will withstand only 2% strain.) The super-elasticity of NiTi allows it to perform functions that would permanently deform other alloys.
Shape memory is a design function of the material's temperature. Nickel titanium undergoes a phase transformation as the material is heated or cooled through its "temperature transition range" (TTR).
If you design a NiTi spring, for instance, to have a transition temp of 100 degrees, it behaves like a regular spring at temperatures above 100 degrees. (Here it's said to be in an austenitic phase.) Below 100 degrees it's weak and pliable like a piece of solder. (This is its martensitic phase).
Heating the spring above its TTR causes the material to recover its former spring shape with considerable force.
The temperature at which this phase transformation occurs can be adjusted over a wide range. (See Document Center for glossary of terms)
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Make no mistake
When NiTi is right for the application there is no substitute.
Conversely Nickel titanium in not for everyone. Its manufacturing processes are unconventional. (Just ask traditional spring companies, many of whom come to us when they're asked to quote a nickel titanium product.)
To see if NiTi is right for you, Contact Us.
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