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Rare Earth Magnets/supplier needed

Postby rkuchinsky » April 5th, 2016, 11:53 am

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rkuchinsky
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Hi All,

Polymagnet topic cool, but this is a bit different so didn't want to clutter the thread.

I'm working on a project now that includes magnet, but it's my first time working them.

1. What are the physical property specs I should know/can ask for to determine strength, etc.?
2. Anyone got a good magnet supplier in China? Specifically Dongguan area would be great. Samples I got so far are not that strong and I think can be better.
3. Are there different kinds/materials of magnets that are better than others? More cost effective, etc?
4. Any general suggestions to getting good magnets, application tips, things I should ask for, etc? My application is in soft goods and magnets are being sewn/stuck beneath fabric layers.

Thanks,

R
Richard Kuchinsky / Directive Creator
http://www.rkuchinsky.com

The Directive Collective
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Re: Rare Earth Magnets/supplier needed

Postby NURB » April 5th, 2016, 9:28 pm

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I've used these guys before.

https://www.kjmagnetics.com/

They're US based, and might be able to be a good starting point for you. Lots of info and lots of various sizes and strengths of magnets. Maybe you'll have better luck from your suppliers if you've got some specific strengths to spec.
Chris Haar

twitter:@chrishaar

Those who define design as knowing how to use Illustrator will be condemned to using Illustrator their entire career. - @monteiro

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ralphzoontjens
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This is my supplier:
https://www.supermagnete.de

Datasheets are available on the website.

The neodymium magnets are extremely strong.
You can heat press them onto fabric under adhesive film such as Heat'n Bond, due to the heat they will lose a bit of strength so you will have to do a few tests, but it works perfectly.

Re: Rare Earth Magnets/supplier needed

Postby Cyberdemon » April 6th, 2016, 12:56 pm

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As far as physical specs, rare earth/neodymium magnets have a rating like "N52" which determines their strength. Sometimes you want a very strong and small magnet, sometimes you just want any magnet. This will determine the pull force it takes to remove something from the magnet. Different magnets have different properties (temp resistance, resistance to dropping) that you can find on the Google or ask the vendor to recommend based on your application.

Also important is magnet fall off. Two magnets in contact are very strong, two magnets slightly further away will still attract, but with a falloff curve. This can actually be used to an advantage if you want something to attract, but not retain so strongly it requires a huge force to remove. I designed a phone cradle which uses a magnet to draw the device in, but it has just enough separation to never touch and makes it easy to pop out with 1 finger.

Re: Rare Earth Magnets/supplier needed

Postby rkuchinsky » April 6th, 2016, 2:16 pm

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Thanks all for the suggestions. Going down the rabbit hole.

NdFeB seems to be the type I'm after. Aside from the number (ie. N52), I'm having a bit of trouble understanding all the other specs. Anyone know their way around all the numbers? (Residual Flux Density (Br), Coercive Force(Hc,)Intrinsic Coercive Force (Hci),Max.Energy Product(BH)max, Gauss, Pull force, etc. What's important? How do I figure out what I need?

Any other suggestions for China suppliers greatly appreciated. Esp. in Dongguan Area.

ralphzoontjens wrote:This is my supplier:

You can heat press them onto fabric under adhesive film such as Heat'n Bond, due to the heat they will lose a bit of strength so you will have to do a few tests, but it works perfectly.


What kind of application is Heat'n Bond? I've never heard of that?

Thanks,


R
Richard Kuchinsky / Directive Creator
http://www.rkuchinsky.com

The Directive Collective
http://www.directivecollective.com


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