Memory Wire (Nitinol) questions

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[copied from the Electrical Engineering Other Topics forum]

Here's a question about memory wire, also known as nitinol wire. I'm looking for something that is difficult to cut, and extremely flexible. I'm thinking that the nitinol wire meets my flexibility requirements, but I can't find a spec sheet that will tell me whether it will be easy to cut or not.

The application is a security strap that would be a rubber strap with a wire embedded inside. The goal is to prevent cutting with ordinary scissors while it's worn on a wrist or ankle. Flexibility is needed to allow it to wrap to different sizes, and high security is required to prevent removal.

I'd like to find something that meets these requirements and is smaller than 1/16" in dia. Am I asking too much?

 

[israelkk]

Why not use spring wire?

 

[EdStainless]

Steel spring wire would be my first thought.

http://www.nationalstandard.com/prod_specialty_capabilities.php

might be a place to start. Steel spring wire is very strong and can be used very thin for your application.
If you want more flex you should look at low modulus alloys. Ti wire is very flexible and strong.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[NickelMet]

You might contact Special Metals Corporation (New Hartford location) as to the Nitinol wire information.

product brochure -

http://www.specialmetals.com/products/nitinol.htm

Shape Memory Alloy Department -

http://www.shape-memory-alloys.com

~NiM

 

[jaysch]

Nitinol is amazing stuff. Although, I haven't seen a good spec sheet on this stuff either. Seems to be proprietary?? Special Metals Corporation is a good resource.

 

[NickelMet]

Jaysch:

The links in my previous post will give you a lot on the specifications.

There is a lot that is proprietary concerning the alloy, particularly in the way that it is made. It is not an easy piece of metal to manufacture. And yes, it does some pretty amazing things.

~NiM

 

[JTreglio]

NiTi wire is used extensively for braces (orthodontic). You could check with some of the arch wire manufacturers, such as Highland Metals and G&H Wire. They sell the wire in spools as well as cut and formed into arch wires, so they must know how well it cuts.

Jim Treglio
Molecular Metallurgy, Inc.

 

[Luv2detonate]

How about its applications in sheetmetal (at small scales)?? Also, how about pricing ...how much more expensive are they as compared to available choices of materials for sheetmetal work??

 

[SmithsJohn2]

I know NiTi is so expensive and they are avaiable in thin film or thin wire form. Also the mechanical properties, such as young modulus, stiffnes are dependent on the temperature!

 

[rorschach]

I've machined NiTi pins before, it cuts no worse than 316 SS.

 

[Judson268]

I think that you should have a try use superwlastic NiTi wire, which has low Youngers modle, high hardness and very big elastic strain, about 8%.

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