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How to make an air gap on an E E core?

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neonwarrior

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Hello everyone,

How do I make an air gap on an E E core. What material do I have to insert between the E's to make, for example, a 1 mm air gap.

Thanks in advance.
 

you can use paper for airgap.

1mm airgap in e-e core--> use 0.3mm thickness paper.
 

You can use whatever insulating material with good dimensional stability over the required temperature range. If the gap must be 1 mm, you need about 0.5 mm thick material as you have the gap twice in the magnetic path. If your 1mm is without correction for fringing, you need somewhat more gap, but this you can find by measuring the inductance.

If you want lowest stray field, and the winding is over the middle leg, you should have the gap in the middle leg only. In case of a single prototype only, you can grind the gap by hand with a Silicon Carbide sharpening stone. It takes time, but is possible, I did it several times. Make sure you use water with just one drip of soap or other means to make sure ferrite particles do not build up on the sharpening stone.

Disadvantage of having the gap in the middle leg only, may be increased eddy current loss in the winding due to the fringe field.
 
I recommend before actually grinding a gap in any legs, you make a prototype with all legs gapped with some thin material. Mylar film, polyester/kapton tape works pretty well. Once you have the desired overall gap length you can grind down the center leg, if you really want.
 

WimRFP said:
You can use whatever insulating material with good dimensional stability over the required temperature range. If the gap must be 1 mm, you need about 0.5 mm thick material as you have the gap twice in the magnetic path. If your 1mm is without correction for fringing, you need somewhat more gap, but this you can find by measuring the inductance.

If you want lowest stray field, and the winding is over the middle leg, you should have the gap in the middle leg only. In case of a single prototype only, you can grind the gap by hand with a Silicon Carbide sharpening stone. It takes time, but is possible, I did it several times. Make sure you use water with just one drip of soap or other means to make sure ferrite particles do not build up on the sharpening stone.

Disadvantage of having the gap in the middle leg only, may be increased eddy current loss in the winding due to the fringe field.
Click to expand...


The other benefit of setting required gap on middle leg is, Lesser EMI. But then only those who want to comply environmental norms should really bother for this. :)
 
Hi
Why creating ? there are some standard cores with gap space , unless you have calculated your gap space and it is more than the standard cores .
( if your gap should be less than or more than , the gap of standard cores , as Tahmid suggested , you can use a simple paper .
Best Wishes
Goldsmith
 

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