Nitinol wire is a shape memory alloys (SMAs) are a smart material that can ‘remember’ a shape. SMAs will try an return to a remembered shape when heated.The effect of nitinol wire has to be seen to be believed, the odd metal will happily change shape and unknot itself. The shape change also exerts some force when doing so allowing ti to be used as an actuator. The material gets some use in engineering and medical applications but considering its unique properties it should have some more uses by now. Mostly it can be purchased with a memory of being straight or as a spring but other samples do exist.
- Can remember shapes and return to them even after excessive bending.
- Can be programmed with a new shape at very high temperatures
- Are superelastic meaning they can undergo exceptional amounts of bending without weakening.
- Is suitable for medical applications
- Exerts force to return to original shape and can even unknot itself while returning to its original shape.
- Can have electric current passed through to induce a shape change.
- Cannot be easily reprogrammed in average consumer homes
- Heat level required to return to shape often makes material dangerous to touch.
- Fatigue in cool shape causes warping
Manufacture & Fabrication
Nitinol wire is difficult to fabricate as it requires high temperatures to imprint a new shape on the material. The first step is to anneal the wire to loosen it’s atoms and allow it to rest in a new shape. The metal will however while heating but before annealing try to assume it’s remembered shape which can make precise forming difficult with out a good jig.
Durability & Sustainability
Nitinol wire is very durable because of it’s unique internal structure it can undergo repeated bending without becoming work hardened and springs back to form easily. The material will not lose it’s remembered shape over the lifetime of any product it is likely to go into. As for sustainability the material cannot be recycled but can be repurposed easily.
Find out more at Nitinol
Here’s the video the gif is taken from.