Talk:Neodymium magnet

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[edit] Older comments

Both KJ and Gaussboys give "grades" for their magnets (N38, N42, N45 etc.), but don't explain what exactly these mean, other than that higher grades mean stronger magnets. Can anyone shed light on that? Does it have to do with the purity of the material used to build the magnet?

I think this should definitely be covered in the article. -- Schnee (cheeks clone) 22:10, 22 Jun 2005 (UTC)

The typically listed "grade" of a magnet usually refers to the Maximum Energy Product or BHmax. In c.g.s. the units are in Mega-Gauss*Oersted, (MGOe) and they are more internationally known in S.I. units as Joules per cubic meter (J/m^3).

The "N, ND, or NS" prefix usually means Neodymium Iron Boron magnet alloy and the "Grade/number value" suggests that the alloy has a Maximum Energy Product of 38 MGOe. This magnetic characteristic is volume independent and only gives you an idea of what the net magnetic field of a magnet with a particular geometry will be.

The "grade" or Maximum Energy Product is usually not used in an calculations beyond first order and it is really not important in designing with strait line materials. Strait line magnet alloys have a strait normal curve in the II quaddrant their Hysterisis curve at moderate temperatures. The "grade" does help compare similar magnet alloys. This convention is also used in Samarium Cobalt alloys, but these usually start with a "S" or "SC".

Most Neodymium Iron Boron manufacturers allow a tolerance of ±10% on the Maximum Energy Product and this is specified in the MMPA/IMA magnet stanadrds. The International Magnet Association (IMA) is the old Magnetic Materials Producers Association (MMPA)and they have adopted the MMPA standards and definitions.

Usually a higher grade is stronger, but one vendor's strong N38 may be another vendor's weak N40. The grade impact will be transparent to most general purpose users, but industrial users should review the other three primary magnetic characteristics of a permanent magnet; Residual Induction (Br), Coercive Force (Hc) and the Intrinsic Coercive force (Hci). 72.240.22.233 00:13, 20 March 2006 (UTC)

It seems to me that the paragraphs in the "Caution" section should rightfully be reversed. Some people may disagree, but flesh wounds are for the most part worse than equipment damage. And these things can really pinch let me assure you. (71.233.165.69 00:36, 19 May 2006 (UTC))

  • They can do a lot more than just pinch. Larger ones at higher grades are strong enough to attract things from even across a room at high speed. Make sure all your tool boxes and any loose metallic items are secured when moving one.

If somebody is wondering how to expand this article, a section about how those magnet are created would be great! :-) Peter S. 00:58, 15 June 2006 (UTC)

Yeah, I agree. How are Neodymium magnets made?!? ^_^ Jumping cheese Contact 08:54, 29 October 2006 (UTC)
would also like to know exactly how they're made. I've also read comments to the effect that they fade over time - is there any truth behind this? verifiable stuff only please (with citations). dreamcatcher23 (talk) 22:04, 6 April 2008 (UTC)

[edit] Aspirin?

The article mentions toys containing neodymium magnets the size and shape of aspirin tablets. Can someone please replace this with a proper measurement? Even the original Bayer Aspirin is available in different shapes and sizes, let alone all the different stuff called "Aspirin" which is available in the USA. --BjKa 13:52, 8 November 2006 (UTC)

The size of one of these magnets is 2-4 millimeters in diameter and the same high.

[edit] Serious error in the Caution section?

The caution section states that neodymium magnets are not strong enough to pull a paperclip through a hand. I imagine as this is in the "Caution" section, that the intended meaning is that they are able to do that? Then, it should urgently be corrected. —The preceding unsigned comment was added by 82.139.254.221 (talk • contribs).

No - I don't think any consumer neodymium magnet could come close to pulling a paperclip through a hand. I have two 1" cube neodymium magnets and while they can create an uncomfortable pressure when placed above and below a hand, I can't imagine any magnet available to the public pulling an object through a hand. -SCEhardT 22:37, 9 December 2006 (UTC)
I thought 1" NIB could break fingers, I find 12mm cubes cause the most pressure I would like to experance, maybe I have week hands. Alan2here 16:01, 31 July 2007 (UTC)
I also have two 1" cube N45 grade neodymium magnets. As he has said they can give an uncomfortable pressure but it does not really hurt. They can give you a bad pinch though if you let them roll off your hand. My younger brother (younger by 2 years) was stupid and let them come together when he sat down holding one in each hand so that they pryed his fingers apart and snapped together. He got a blood blister that lasted a day or so. I yesterday myself let them come together in a different way and pinched the side of my finger slightly. Looking at it now I can see the red line on the finger still, but it does not hurt anymore. But they are definitely not strong enough to pull things through your hand. You have to remember with your small magnets that pressure is applied over an area. With 1" magnets while the force is stronger the area is a little over four times as much as 12mm magnets. If I focus that into a 12mm area (it is hard to do as you are also getting the magnets farther apart when you do so) it does feel a little stronger, but still bearable.Ergzay (talk) 08:44, 25 February 2008 (UTC)
They definitely can hold up items on another side of your hand. They could not literally pull the item through the hand causing a large cut by any means. Looking at the citation given ( http://youtube.com/watch?v=NKZgGTD0qic ) it has nothing to do with pulling paperclips or objects through hands and looking about I can find no episode that shows so. Aicchalmers 18:53, 30 March 2007 (UTC)
I did find one article about Mythbusters and pulling paperclips through hands (http://www.popularmechanics.com/science/extreme_machines/4199615.html) in which Adam specifically says that it is impossible. So I am removing the incorrect statement and citation.
One of my hobbies is collecting (very strong) magnets, and In my experience, the strongest ones aren't nearly the strength to pull a paper clip through a hand, unless it was a very sharp paperclip. one/zero 20:59, 27 August 2007 (UTC)

[edit] Keeper

A seller of these [[1]] says they do not require a soft iron keeper across the poles to prevent loss of magnetic strength over time, as alnico magnets do. Could someone please find a reliable source for this, and an explanation in thems of the properties of the materials, the hysteresis curve, or whatever. Thanks Edison 15:04, 24 April 2007 (UTC)

While I do not understand the science of such loss you mentioned, I do not think that it is so. In all my looking up about Neodymium magnets (and personal experience with them), although limited, I have not seen anything about them weakening over time. As the article states if they get over a certain temperature they start to loose strength, but I have not seen on any site that sells them (including highly reliable sites like http://www.unitednuclear.com ) anything about them weakening over time. Ergzay (talk) 08:48, 25 February 2008 (UTC)
AlNiCo magnets have a lower Curie temperature. As with all thermally-activated transitions from a metastable state, the weakening of ferromagnets theoretically happens at all times and temperatures, it just appears to stop.
A keeper might be a good idea if your magnets are going to be heated to within a few tens of degrees of their Curie temperature. I imagine the process won't be too noticeable in most events; maybe faster than diamond transforming into graphite, but still too slow to notice.--128.115.27.10 (talk) 17:19, 11 March 2008 (UTC)

[edit] Discussion

Neodymium loudspeakers can stand a higher power (upto nearly 3 times the power) of an ordinary speaker.


According to Eden Electronic research lab these speakers also create a greater heat. This heat will result in the magnets losing their precision, and thus the speaker losing clarity and their defined sound over a time period of a couple of years. —Preceding unsigned comment added by ProDigit (talk • contribs) 07:00, 17 May 2006

--hmmmmm, thinking about this abit and I Believe presion is not the right word, should be power, so the spk might become less efficient and if in a 2,3,4 spk sytem freq response would suffer, no? —Preceding unsigned comment added by Wblakesx (talk • contribs) 18:25, 21 November 2006

What you say is correct, tho if the speaker loses it's magnetic field due to heat, a result is a loss in power, and in clarity. Imagine a 15" coned speaker being driven by a magnet the size of a small pill. Not only will the small magnetic field be too weak to move the cone; the sound will also be deformed, lacking bottom end, and high (or crisp) sound, due to the delay that the mass of the cone causes.

According to more information I have received, the Neo magnet reacts different in sound then a standard magnet. the sound in audio speaker systems driven by Neo magnets similar to standard magnets seem to lack some form of bottom end. this problem can be helped by lengthening the magnet, making it more punchy. Though above 'trick' will not create speakers delivering a sound true to their source (so it seems).

Much like the former Alnico 5 magnets, the Neo magnets with a higher percentage of neodymium will lose their magnetic field faster then ones with less Neodymium in the alloy. The drawback of decreasing Neodymium in the magnet is that it will result in heavier magnets, having less magnetic field.


Aren't they use in permanent magnet motors? any comments? And as far as speakers go, musicians don't necessaily want perfect speakers. What do they think of Neod speakers? —Preceding unsigned comment added by Wblakesx (talk • contribs) 17:04, 19 November 2006

Sony using this Neodumium in their latest headphones. [2]

[edit] External Links

I was wondering if anyone had opinions on my adding a link to a site that sells a wide variety of Neodymium and Samarium Cobalt magnets. The only drawback is that in addition to selling magnets for normal uses he also sells "medical" versions for the so called magnet therapy.

Here's the link for those interested to review, I'm new to editing so opinions on the appropriateness of this link are welcome.

Engineered Concepts (Super Magnet Man)

Fatal shadow 00:46, 17 July 2007 (UTC)

http://www.unitednuclear.com/ also has a nice setup and they also include warnings and info about magnets and (IMO) a more user friendly site. The direct page for their magnet page is at: http://www.unitednuclear.com/magnets.htm The only drawback is that they only ship to within the United States. It might be a possibly good idea if we are going to put them down to put them both down. They also sell larger magnets than that website. Also all their magnets are N45 grade. Ergzay (talk) 09:13, 25 February 2008 (UTC)

[edit] Free energy

I'm 15 and I'm fascinated with the new development of 'free energy' I saw on YouTube by developers who are using magnetic fields to defy the laws of science and have created a perpetual motion machine== http://www.youtube.com/watch?v=BNDIWY19gqA&mode=related&search= == I think their discovery will go down in history as the greatest of all time. And I really admire that they are going to give the technology for free to 3rd world nations to level the playing field. I'm guessing that the magnets they are using are one from the family of super magnets but does anyone know or have an idea which kind of magnet they might be using?Sasha2991 07:17, 10 August 2007 (UTC)

Please my friend do not be fooled by things like these. I am 18. 'free energy' is impossible. It cannot be discovered because it breaks all rules of physics. You CANNOT defy physics. There are at times when you can exploit loopholes in the physics, but this is a rare case. Every single "free energy" device in history has been invented by people who do not know physics and have just discovered something that people already knew about and what they are really doing is using energy from someplace they do not understand. That video really makes sky news look quite bad and show how ignorant they are. If you look into it, you will find no where that they actually tell what they do. What they are really doing is lying through their teeth to get publicity for whatever other products they are selling. Whey they talk about nonsense like "religious" and other nonsense is because the rules of thermodynamics really are completely solid. People misunderstand electromagnetism a lot or try and make other people misunderstand it to make them think they are actually making energy.Ergzay (talk) 09:25, 25 February 2008 (UTC)
I haven't looked too far into this particular case - but I'd be wary. Such "free energy" things usually fall into two categories - either they're wrong (the physics isn't understood and the energy is coming from someplace they don't know about - like heat from the environment, the turning of the earth, the energy that can be stored in non-permanent magnets etc.) or they're wrong AND they're a scam, aimed to con investors out of their money. As a physicist, I know it's shortsighted to say something can or can't be done with absolute certainty, as we've had so many examples in the past of people being proved wrong. However, with the current understanding of physics "free energy" machines are (sadly) a impossible. Until someone is willing to allow their invention to be fully investigated and documented by able, qualified people, it's best to avoid being drawn in by such hype & pseudoscience. dreamcatcher23 (talk) 14:24, 6 April 2008 (UTC)

[edit] N and BH(Max)

In the specifications of many magnets, it shows BH(Max) as a range of MGOe (for example, http://www.hitachimetals.com/product/permanentmagnets/neodymium/properties.cfm), and the "N" rating appears to be a bit lower than the median of that range. The article says, "The number after the N represents the magnetic energy product, in megagauss-oersteds (MGOe)..." The Hitachi Metals page shows that their HS-55AH product has a range of 53-56MGOe, but I've seen no indication that this is marketed as an N56 magnet. Does anyone know how the "N" number is being calculated from the BH(Max) range? I think the article would be improved by adding that detail. Fungicord (talk) 11:19, 1 January 2008 (UTC)

[edit] One more reference

I noted that all references are for commerical sites. The following one has (comparatively) lots of useful info:

http://www.kjmagnetics.com/faq.asp

For example if you're interested in temperature dependance, you get actual data at this site (unlike most others).

I don't feel like adding it in the article though, since then probably someone will accuse me for adding commercial links.. --88.131.22.138 (talk) 14:34, 21 January 2008 (UTC)

[edit] NIB wiping credit cards

I once saw in a mythbusters episode where they did wipe a credit card with a NIB it was in the eel wallet episode does that count as a citation? —Preceding unsigned comment added by 69.230.121.21 (talk) 16:22, 13 March 2008 (UTC)