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Magnet Nd-Fe-B vs Al-Ni-Co

Magnet Nd-Fe-B vs Al-Ni-Co

Magnet Nd-Fe-B vs Al-Ni-Co

Hi all!

I am a new member of eng-tips.com ^^

my company is speciliazied in Earphone and the magnet NdFeB is in used. The Spec is like this OD 5 x ID 2 x 1 mm, BH(max)kj/m3: 263~279, Br: mT(SI) 1.17~1.22, Hc: kA/m 860 MIN, Ep-REFe by Zn or CU+Nib. I am curious about the Al-Ni-Co magnet,if i change to Al-Ni-Co, does the magnet's feature stay the same? its cost would be higher or lower? if Al-Ni-Co can not, which kind of compound can replace it? pls advise me.

Thanks a lot

Wish you all a nice day ^^

RE: Magnet Nd-Fe-B vs Al-Ni-Co

Alnico will give you high Br, but very low H.  Depending on the reluctance of your circuit it may not work.  Alnico 5 magnets tend to be longer and the air gaps smaller. This way they work higher on the curve, near Br.
The Alnico would not need any corrosion protection.
The rest of the features don't really apply to your application.
Neo will give you the highest energy densities and best performance.

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Plymouth Tube

RE: Magnet Nd-Fe-B vs Al-Ni-Co

If you can tolerate a 5 to 10% reduction in performance, SmCo may be an option.  Currently it is cost-effective with NdFeB.  

One other benefit:  SmCo wouldn't need any corrosion protectcion in that application.

RE: Magnet Nd-Fe-B vs Al-Ni-Co

thanks Edstainless and MagMike, so it means Al-Ni-Co does not give a chance T_T. how about the Fe-Cr-Co magnet? i have read on some website and checked that the characteristic is quite similar to Nd-Fe-B, could it stand a chance?

the other thing is that, i noticed that in the material code of the magnet there are usally some lettes like H, UH etc... the Engineer in my company has no idea what it is, i supposed it is some kind temperature related to that, pls advise about this one?

The last thing i wonder is, the Sm-Co magnet (as posted in some websites) has the highest price (even higher than Nd-Fe-B), is it true?

thanks for your kind help

RE: Magnet Nd-Fe-B vs Al-Ni-Co

Fe-Cr-Co does not have sufficient coercivity to work in your application.

The H, UH, etc letter codes refer to the intrinsic coercivity of the NdFeB material.  Generally H means a minimum intrinsic coercivity of 17 kOe, SH for 20 kOe, UH for 25 kOe and so on.  The higher the intrinsic coercivity, the higher the operating temperature.  

Up until a few months ago, SmCo was one of the most expensive magnetic materials.  However, the recent price spikes in the raw material for NdFeB has changed this.  Things may revert, but at the moment, SmCo is cost competitive with NdFeB if your application requires magnets with energy product in the 30 to 32 MGOe range (237 to 252 kJ/m^3).

RE: Magnet Nd-Fe-B vs Al-Ni-Co

Thanks MagMike and thanks all, i am such a dummy about all these stuffs, i will learn more about the specification and asking u guys more.


Have a noce day ^^

RE: Magnet Nd-Fe-B vs Al-Ni-Co

Dear all!

i have question about the coating materials. Currently, the applied coating for magnets of our company are Ni, Cu-Nib 10, Zn. Some people said the Zn itself is not as strong as Ni and Cu-Nib(the coating thickness stays the same: 10 mic) Is that correct? pls advise me.

Regarding to the coating cost, can epoxy or Parylene coating be cheaper? pls suggest me.

one last thing i want to learn is about the H --> UH series (in magnet materials code). As what MagMike told, I want to have a list of those series for reference, if somebody knows, pls show me.

Thanks for your kind help ^^

RE: Magnet Nd-Fe-B vs Al-Ni-Co

Sorry all, i miss this question.

i knew the magnet has the coercivity (Hcb) to keep itself from being demagnetized, but there is something call intrinsic coercivity (Hci). i have checked the internet to get some information about it, but it sounds too tough to understand (there are formulars... kind of expert thing made me confused) may you explain it more simple about the Hci, and the difference b/w Hcb and Hci?

Thanks a lot dear!!!

RE: Magnet Nd-Fe-B vs Al-Ni-Co

metalparts: It is common practice on EngTips to start a new thread when new questions are introduced.  This makes it easier for people when they do a search on a particular topic.

Please start new threads for you questions.

RE: Magnet Nd-Fe-B vs Al-Ni-Co

Regarding H-UH series, the main difference is HCJ and max. working temperature, here is the details:
H(HCJ>17KOe, max. working temp. 120centigrade)-SH(20KOe, 150centigrade)-UH(25KOe, 180centigrade)-EH(30KOe, 200centigrade)-AH(230centigrade)
The other magnetic property are almost the same. If you need more, you can give me your email, so i can send some materials to you.

RE: Magnet Nd-Fe-B vs Al-Ni-Co

thanks Magmike's and Leslie2000's comment.

@Leslie2000: pls send me the reference to phungxuongtuan@gmail.com, thanks a lot.

i supposed that adding new question in the same thread will save more space. Now i knew the rule, thanks for your reminding

RE: Magnet Nd-Fe-B vs Al-Ni-Co

In old systems that were designed for low H materials all that mattered was Br.  These had long magnetic circuit lengths and small air gaps.  In test cases Alnico 5, Vicalloy, and similar alloys could give great performance.
These older non-rare earth alloys are very stable with temperature and are very corrosion resistant.

That said, if you are looking at alloys don't overlook the 2:17 SmCo grades.  They have higher Br and Energy than the older 1:5 SmCo alloys.

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Plymouth Tube

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