Do neodymium magnets loose energy?

[wireheads]

Generally, most of the research I have done says that neodymium magnets do not loose their energy, even when dropped or around other magnets, and will last 400 years. But what about if the neodymium magnets are constantly in motion and interacting with each other?

 

Our system has a Sphere neodymium magnet moving along a "magnet track" with Cylinder neodymium magnets, similar to this Youtube video:

 

We need to know HOW MANY PASSES a sphere magnet can make before the cylinder magnets along the magnet track loose 10% of their energy. Our system has a sphere magnet passing at a speed of about 1.0 m/s, 3 times per second, so lots of magnetic activity. That means 94,608,000 passes a year!

 

Can the energy loss of energy for the Cylinder neodymium magnets along the magnet track be calculated ?

 

Sphere magnet:

1 1/2" diameter Grade N42 - Nickel Plated

http://www.kjmagnetics.com/proddetail.asp?prod=SX8

 

Track magnets:

1/2" dia. x 1/2" thick Grade N42 - Nickel Plated

http://www.kjmagnetics.com/proddetail.asp?prod=D88

 

The sphere magnet is moving at about 1 m/s.

 

The cylinder magnets along the magnet track are about 0.25 inches from the surface, so the sphere magnets are always 0.25 inches away from the cylinder magnets.

 

I do need a complete calculation that I can show to someone with a Ph.d. in physics who would agree with the calculation.

 

Can anyone help?

[Enthalpy]

I do agree that demagnetization is a story of the past. AlNiCo was plagued with it, FeNdB isn't.

 

FeNdB can be put front-to-front so that zero flux passes and they don't lose strength. No idea where the often cited figure of 400 years comes from: manufacturers give no limit.

 

I'd say varying fields won't do anything, because alternators let Nd magnet work in varying fields (created by the induced current in the stator windings) and they keep their strength. From the distances observed on your video, your varying component must be smaller than theirs, and at wind turbines, the induction varies around 50 times per second over decades (1.5e9 times a year).

 

Any loss must be hard to predict, since manufacturer give no data about it. In case of doubt (I have none) or if you need a proof for someone, I suggest to experiment it with a couple of magnets that you rotate with a motor. At 1500/min over 46 days, you have your 100M passes.

 

The best method I found to measure the magnetization intensity of magnets was to hold them with a thin wire so they rotate freely, and measure the oscillation period in a known field. Earth gives one for free, or Helmholtz coils give a stronger one - add and subtract Earth's field over two measurements to compensate it, just use the squared frequencies.