Nitinol Wire

“muscle wire”

Opto-coupler, globe, motor,

INTRO

NITINOL WIRE

Nitinol wire is a very interesting output device or INDICATOR. It is a wire that DECREASES in length when a current flows through it. This is opposite to thermal expansion, where heating create an expansion. IN this case heating creates a contraction about 100 times greater than normal expansion. Current through the wire produces heat and the amount of current must be carefully controlled (limited) so that the wire does not get too hot. The wire is only allowed to rise to a temperature to produce approx 6% reduction in length.
There are a number of comments about this wire. It is very expensive ($xx per metre) and the speed of activation is about 1second for contraction plus approx 1second for the wire to cool and return to its original length.
The other limiting factor is the need for a force to return it to its original length. It does not return by itself. The wire we use for the experiments is 0.004in (4 thousands of an inch) in diameter. It produces a force (lifting power or pulling power) of xxxgm.
The force required to return it to its original length is xxxgm. If this returning force is present all the time, the effective output force is 65gm - 25 = xxxgm.
If you have an application that meets these requirements, this project can be very impressive.
We have produced a 3-page technical article on NITINOL wire with a list of suppliers, applications and complete technical details.