Measure flux density of NdFeb magnet

[haolian]

I would like to measure the quality of NdFeb.


Following is the specification of the magnet

Dimension: 5 x 5 x 2 mm
Magnetization: 4 poles on each 5x5 mm^2 surface. (4 equal quadrants surface... like rice field)

I would like to determine magnetization quality like the
- Flux density
- &quot;airgap&quot; dimension separating N..S..N..S. The width of the line is about <0.2mm.

Can anyone suggest a simple method to measure these parameter?

 

[hacksaw]

what equipment do you have available?

 

[haolian]

I have a Gaussmeter meter (GM05 by Hirst), many hall elements.

 

[hacksaw]

I believe the correct way is to design a fixture with an closed flux path (soft iron yoke, for example) with a small air gap where you perform the measurement. it might be more difficult than it is worth because of the geometry of your part. the field in the gap to the &quot;net&quot; flux conducted through the measurement yoke. the big question is making certain that the &quot;net&quot; flux is representative of the material.

meas. of the field next to the pole face without a yoke, is going to be a sum of the fields produced by all adjacent magnetized surfaces. it will scale (be proportional to) the number you are after but it won't be absolute because of the geometrical factors.

force measurements (lift-off force from soft yoke) that are possible, but they too are indirect and require a lot of work to develop calibration factors.

one thing that you can do is to develop a &quot;go by test&quot; wherein you measurement &quot;flawed&quot; though it may be is performed consistently. once you quantify the readings for a good part, you hold all others to that &quot;standard&quot;.

good luck