Hello there all of you,
It's been a while since I was active here, my apologies but I've been working hard.
All the stuff below has probably been covered before on this board in lots of places but since the question just came up on the IRC channel I figured I'd write up the answer in a bit more structured way.
How to handle Neodymium magnets (neos) safely when building windmills or other projects:
Neos are amazing stuff to play with, but they are not without risk.
Before we can delve in to that let's first take a look at how they are produced:
Neos are made by compressing (using a tool and die press) a precisely measured out quantity of pulverized material that is not yet magnetic in to the shape of the finished product. This produces a rough surfaced 'blank'.
This blank is then coated with a thin film of metal to stop the base material of the magnet from oxidizing.
(this is why it is bad to strip away that layer, if it should flake just leave it
or close it off with some glue, don't pry off the layer because you'll only expose a larger part of the magnet to the air, which will rust away before your eyes.)
After that the blank is magnetized using an electric current that is passed through a coil. This current is extremely high but lasts very short, and it puts the magnet in such a strong magnetic field that when the current is turned off the magnet particles remain oriented along the fieldlines of the field created by the current.
Because the original material was based on a rough powder, and this powder inside it's thin metal jacket has now been magnetized to a very high degree you are basically looking at a stack of very small magnets that repell and attract each other in complicated ways kept in check by that jacket and the bonding material that was used when they produced the blank.
On the whole the best way to look at this is as something under a lot of tension that is held back but only just so. Any kind of crack in the magnetic material has the potential to unleash the force with which the pieces of the magnet want to separate and then recombine at a lesser energy state. In other words if you crack a neo badly enough pieces will fly off and will then recombine with great force, possibly sending shrapnel like pieces in all directions with great velocities.
I've had this happen to me just once but believe me I could have done without the experience.
So, after this bit of basic magnet construction on with the safety aspects.
To avoid trouble with neos here are a few basic tips on how to handle them:
- always wear gloves when handling larger (say anything over a 1"x1/4" disc)
magnets to avoid getting your skin pinched between two of them
- wear safety glasses, in case a magnet should escape your grip and smash in to another one or something else
- if possible have magnets you are not currently working with (as in placing them right now) attached to something made of steel
- handle only one magnet at the time
- place a magnet on the steel carrier a bit away from its final position (and away from other magnets) then slide it into position. That way you avoid the extremely strong magnetic fields over the other magnets by approaching them from the side. The last one is always pretty tricky because you'll have less space to work with so that's a good time to be extra careful.
I hope this helps. I'm sure there are tons of people on this board that will consider all this stuff a waste of space and time but these are not toys and to treat them without the respect they deserve is asking for trouble.
take care,
Jacques.
