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Old 22nd July 2005, 03:50 PM   #1
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Question Adding Magnetic Properties In Femm ?

Admitedly, I am somewhat of a magnetic circuit moron. I have, however been able to figure out Femm, and have been using it to model various potential ribbon magnet frames.
My trouble started when I decided to see how N50 performed compared to N40 (is it worth twice the price ?). I was able to find several sites with properties charts like this one.....

Click the image to open in full size.

....but these are the properties Femm wants...

Click the image to open in full size.

Coercivity is obviously there...but Relative u isnt ( or rather it's there and my moroness is preventing me from seeing it). Could someone let me know how to convert what I have into what I need ?

Its also interisting to note the descrepency between the coercivity that Femm lists and that of this mfg.. Isn't there a standard, ie, shouldn't sample A's N40 match Sample B's ?

Thanx,
Casey
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Old 25th July 2005, 12:35 PM   #2
JohnL is offline JohnL  United States
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Hello,

Let me start by saying, I am also not an expert in magnetic physics. However, I had the same questions you did. I looked at the difference between 2 magnets that had similar difference in their properties (say N32 and N40) and modeled the differences from that. For my purposes, the differences were pretty minor. It seemed that more could be done with optimizing the motor design, than by changing to a higher performance material (both for perminent and soft magnetic parts). YMMV

Also, there is a FEMM forum on Yahoogroups where you might want to pose these questions (maybe you'll get a more educated response).

John
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Old 25th July 2005, 03:41 PM   #3
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Thanx John for the reply…I was beginning to think my question was s-o-o-o dumb that I had embarrassed myself for asking it.
You seem to confirm my suspicions that N40 represents the point of diminishing returns, that is you have to spend twice as much (N50) for a relatively small improvement.

Quote:
Also, there is a FEMM forum on Yahoogroups where you might want to pose these questions (maybe you'll get a more educated response).
Looks like I’ll be joining yet another group.

Thanx,
Casey
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