FLEXINOL® Technical
and Design Data - Metric
If Flexinol® actuator wire is used within the guidelines
then obtaining repeatable motion from the wire for tens
of millions of cycles is reasonable. If higher stresses
or strains are imposed, then the memory strain is likely
to slowly decrease and good motion may be obtained for
only hundreds or a few thousand of cycles. The permanent
deformation, which occurs in the wire during cycling,
is heavily a function of the stress imposed and the temperature
under which the actuator wire is operating. Flexinol® wire
has been specially processed to minimize this straining,
but if the stress is too great or the temperature too
high some permanent strain will occur. Since temperature
is directly related to current density passing through
the wire, care should be taken to heat, but not overheat,
the actuator wire. The following chart gives rough guidelines
as to how much current and force to expect with various
wire sizes.
| Diameter Size (mm) |
Resistance (ohms/m) |
Pull Force* (grams) |
Approximate**
Current at Room Temperature (mA) |
Contraction**
Time (seconds) |
Off Time 70° C "LT" Wire*** (seconds) |
Off Time 90° C "HT" Wire*** (seconds) |
| 0.025 |
1424.8 |
8.9 |
45 |
1 |
0.18 |
0.15 |
| 0.038 |
889.5 |
20.0 |
55 |
1 |
0.24 |
0.20 |
| 0.050 |
500.0 |
35.6 |
85 |
1 |
0.4 |
0.3 |
| 0.076 |
232.2 |
80.2 |
150 |
1 |
0.8 |
0.7 |
| 0.102 |
126.0 |
142.5 |
200 |
1 |
1.1 |
0.9 |
| 0.127 |
74.8 |
222.7 |
320 |
1 |
1.6 |
1.4 |
| 0.152 |
55.1 |
320.6 |
410 |
1 |
2.0 |
1.7 |
| 0.203 |
29.1 |
570.0 |
660 |
1 |
3.2 |
2.7 |
| 0.254 |
18.5 |
890.6 |
1050 |
1 |
5.4 |
4.5 |
| 0.305 |
12.2 |
1282.5 |
1500 |
1 |
8.1 |
6.8 |
| 0.381 |
8.3 |
2003.9 |
2250 |
1 |
10.5 |
8.8 |
| 0.508 |
4.3 |
3562.6 |
4000 |
1 |
16.8 |
14.0 |
*
The pulling force is based on 172 MPa, which for many applications is the maximum safe stress for the wire. However, many applications use higher and lower stress levels. This depends on the specific conditions of a given design.
**
The contraction time is directly related to current input. The figures
used here are only approximate since room temperatures, air currents,
and heat sinking of specific devices vary. On small diameter wires
(</= 0.152mm diameter) currents which heat the wire in 1
second can typically be left on without over-heating it. Both heating
and cooling can be dramatically changed (see section 3 of the technical
characteristics at http://www.dynalloy.com/TCF1140.pdf for more information.)
*** Approximate cooling time, at room temperature in static
air, using a vertical wire. The last 0.5% of deformation is not used
in these approximations. LT = Low Temperature and HT = High Temperature
Flexinol® Actuator wire.
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