
Nitinol Engines (1992) - blacksqr
http://free-energy.ws/nitinol-engines/
======
mojomark
Application of the subject aside, Nitinol is fun to play arround with. If you
want to tinker, this book comes with a coil of Nitnol wire to use in the demos
contained in the book:

[https://www.robotshop.com/en/muscle-wires-sample-
kit.html](https://www.robotshop.com/en/muscle-wires-sample-kit.html)

In my experience, challenges of Nitinol (a.k.a. 'muscle wire') for use as a
electoactive linear actuator is that if you're not careful you can over heat
(or apply too much tensile load to) the wire and it will permanently deform
(lose it's memory). Still, and interesting material to toy around with.

~~~
Raphmedia
There is also a deluxe kit that comes with more wire. 1 meter of each kinds
instead of 20cm & 40cm wires.

[https://www.robotshop.com/en/muscle-wires-deluxe-
kit.html](https://www.robotshop.com/en/muscle-wires-deluxe-kit.html)

(Disclaimer: I work at RobotShop in their Web & IT team -- I have nothing to
do with marketing though and I'm just a fan of Hacker News.)

------
proee
One problem with Nitinol is that it has a limited number of cycles before the
material becomes weak and then breaks or no longer returns to its proper
state.

This is a major limitation on "muscle wires" when using them for products that
require a high number of cycles of greater than 100k.

~~~
ncmncm
Where are you getting this? The credible sources I find say they improve with
use.

~~~
proee
Here is a good article showing thermal and mechanical fatigue. You can see
under moderate mechanical stress, it fails between 1e5 and 1e7 cycles. While
that sounds like a lot, consider that there are 3e7 seconds in a year.

So if you had a mechanical device that operated at 1HZ, it would fail in less
than a year.

[https://www.nitinol.com/wp-
content/uploads/2011/05/Pelton-20...](https://www.nitinol.com/wp-
content/uploads/2011/05/Pelton-2011-NiTi-Fatigue-Microstructures-and-
Mechanisms1.pdf)

~~~
blincoln
How difficult/expensive is it to recycle the material? i.e. if one had some
sort of wonder-generator based on it, would it make sense to use a model where
once per year, the owner sends the nitinol pieces back to the manufacturer
(who recycles them) in exchange for a discount on replacements?

I assume since titanium is part of the alloy, just discarding it after use is
probably not great from a cost perspective.

------
wigiv
I balked at first glance because "free energy," but here we have a unique
method for turning thermal into kinetic energy. Slightly outside the bounding
box of this energy system, of course, lies the expending of more energy than
what's produced to keep the hot water hot and the cold water cold.

But using natural low-grade temperature differentials as the author suggests,
what might this arrangement achieve that a Stirling engine doesn't? More
torque? Advantage of fewer moving parts? Novelty only?

~~~
imode
We already have this unique method via Nichrome wire. You can see a really
neat application of this in a common toaster here:
[https://www.youtube.com/watch?v=1OfxlSG6q5Y](https://www.youtube.com/watch?v=1OfxlSG6q5Y)

~~~
dirktheman
Technology Connections is my favorite YouTube channel. He's just so good in
explaining the technological intricacies of everyday things, and his humor is
so wonderfully snarky. I highly recommend turning on the subtitles as well, he
puts a lot of effort in them.

~~~
greypowerOz
"oh, god... he has a third one"

excellent writing and delivery, and yes, usually an easter egg or two in the
CC ;)

------
dmitrygr
Nitinol is also used in the smallest & lightest servos you can buy:
[https://www.micronwings.com/Products/Servo%20Biometal/BioMet...](https://www.micronwings.com/Products/Servo%20Biometal/BioMetalIndex.shtml)

------
tke248
Seems like you could make a fan out of this stuff that could be used to vent
the heat from air conditioning units instead of using electric fans.

~~~
andbberger
I guess you could... but that would be complicated and expensive and electric
fans are pretty efficient anyway.

------
frogger101
The omnipod insulin pump, by insulet, uses this in a clever way.

[https://journals.sagepub.com/doi/full/10.1177/19322968187988...](https://journals.sagepub.com/doi/full/10.1177/1932296818798836)

------
52-6F-62
The attached CNN video is fascinating. It seems a shame that the research
seemingly abated.

Can anyone else speak to whether more work is being done into the metal or its
applications?

~~~
thecount122195
I recently went to a talk at my university on microcombusters but the
professor (I cant remember his name off the top of my head) was also working
on small insect like drones. There were videos of nitonol powered beetle
crawling and a non flying prototype of a bee drone with nitinol wing flappers.
Rather cool but he said they are incredibly inefficient compared to
traditional electric motors.

~~~
ncmncm
You can make very tiny motors with nitinol, but it is a real waste of the
capability of the material.

Those work by using electrical resistance to heat a sample, which moves, and
then cools off and can be moved back again, such as by a spring. Turning high-
grade electrical energy to low-grade heat, thence to motion, wastes most of it
(probably ~70%) vs. a magnetic motor that wastes normally less than 10%.

But nitinol can extract high-grade mechanical energy (kinetic energy of
motion, or potential spring tension) from existing low-grade heat by
conducting the heat from a higher temperature source to a lower temperature
sink. I don't know why the other commenter claimed they wear out; the reported
experience from labs was that after 20M cycles they were (a little) stronger
than they began.

~~~
kybernetikos
What sort of orders of magnitude are we talking about here? Could you wind a
watch with body heat?

~~~
pjc50
You have to find a way of applying and removing the heat in order to make that
happen - for watches I would have thought the normal "self winding" kinetic
mechanism was best.

------
tshanmu
Any advice on where to get started on nitinol alloys/engines as a layman
tinkerer?

~~~
ctack
[https://www.robotshop.com/en/muscle-wires-sample-
kit.html](https://www.robotshop.com/en/muscle-wires-sample-kit.html)

~~~
tshanmu
thanks!

------
leptoniscool
The "Earth Engine" is also similar?

------
eeZah7Ux
"Free Energy" wackos? _facepalm_

~~~
tetraca
Even though you can't win against thermodynamics, Nitinol wire seems fairly
neat.

