magnetize ferrite with rare earth PM - energy?
magnetize ferrite with rare earth PM - energy?
(OP)
We're looking at magnetizing a small bonded ferrite magnet using sintered neodymium magnets. It looks doable, but I'm confused about the energy aspects of this system.
Looking at the max energy products, bonded ferrites are roughly 1.5MGOe, while N52 magnets are 52MGOe. Multiplying through their respective volumes I get energies of 7mJ for the ferrite part and 13J for the neo magnets, a ratio of about 20kJ/J.
Of course this is a simplification as neither will be operating at their maximum energy potentials, but what else is missing here? Does this imply that this system will demagnetize the neo magnets over (very roughly) 20k parts?
The magnetizing system I've drawn up in FEA utilizes a steel yoke and has a relatively small air gap, and it appears that the neo magnets are operating at a good permeance coefficient and are not at risk of demagnetizing... is this not the case?
Looking at the max energy products, bonded ferrites are roughly 1.5MGOe, while N52 magnets are 52MGOe. Multiplying through their respective volumes I get energies of 7mJ for the ferrite part and 13J for the neo magnets, a ratio of about 20kJ/J.
Of course this is a simplification as neither will be operating at their maximum energy potentials, but what else is missing here? Does this imply that this system will demagnetize the neo magnets over (very roughly) 20k parts?
The magnetizing system I've drawn up in FEA utilizes a steel yoke and has a relatively small air gap, and it appears that the neo magnets are operating at a good permeance coefficient and are not at risk of demagnetizing... is this not the case?
RE: magnetize ferrite with rare earth PM - energy?
BTW: NdFeB magnets are oftentimes used to magnetized flexible ferrite strip material. With the correct configuration, it should work for your bonded ferrite magnet.
RE: magnetize ferrite with rare earth PM - energy?
My question is essentially, where does the energy come from? Does the energy transfer from the magnetizing system to the part as it's magnetized? (It has to come from somewhere...) Does this energy transfer slowly demagnetize the neo magnets?
RE: magnetize ferrite with rare earth PM - energy?
I have never done this, but I feel this shuould work to magnetize the ferrite magnet. Take care that your impact should not physically damage neither of the magnet both ferite and NdFeB
RE: magnetize ferrite with rare earth PM - energy?
I already have a solution to create the necessary field strength from PMs, just wondering about energy and longevity.
RE: magnetize ferrite with rare earth PM - energy?
RE: magnetize ferrite with rare earth PM - energy?
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RE: magnetize ferrite with rare earth PM - energy?
I had the same confusion as RyreInc did not long time ago.
b.t.w., permeance coefficient is unlikely a factor to affect demagnetization for RE magnets since normally the B-H curve is a straight line. It does matter for AlNiCo magnets where the intrinsic and normal B-H curves are similar, and non-linear.
RE: magnetize ferrite with rare earth PM - energy?
On the Ferrite magnet, the impact of the magnetic field of NdFeB magnet will influence. If you place the ferrite magnet between 2 magnets of 2 pole of N52, you can see the impart of magnetism in the ferrite magnet however it may not be saturated.
While you give some dynamism for the N52 magnet and subject your Fe magnet in the field of N52 dynamism, then your Fe magnet would magnetize sooner.
If you compare the spec of BH of Fe & N52, you may see Fe magnet is much lower (around 30 times) to N52 magnet.
On the Ferrite magnet under magnetized condition, and if you disturb the Fe magnet with N52, your magnetism of Fe will be disturbed.
RE: magnetize ferrite with rare earth PM - energy?
MagBen's comment is enlightening as well, but I will have to take some more time to fully wrap my head around that.