How to fix a broken ferrite core?

[ali6x944]

Hi every one,
I was salvaging some inductors from old p.s.u and I accidentally cracked and broke one of the cores
Not meaning glue failure in an E type core but a real broken core ...
This is it:
https://drive.google.com/file/d/0B5vW-k7HbsL4OVBibTcxN3plOW8/view?usp=drivesdk
https://drive.google.com/file/d/0B5vW-k7HbsL4YlB0QXZiOUVDNUU/view?usp=drivesdk
https://drive.google.com/file/d/0B5vW-k7HbsL4MnJvTWphNWJSN1k/view?usp=drivesdk

[rs20]

Not all of your pics are publically viewable. Try viewing them from a incongnito tab to test if a random on the internet can see it.

More than likely you can just glue the bits back together. Sure, the inductor will be a little more "gapped" than usual, but it shouldn't have a particularly major effect? Maybe? Unless it was a totally ungapped core to start with.

[ali6x944]

Should I use epoxy

[T3sl4co1l]

Superglue or epoxy will do, yes.  Position the fragments as well as you can.  If it's just a few pieces, this is easy.  If it's shattered into dust, consider locating a same-size replacement core (take careful measurements in case the original was gapped).

Tim

[ali6x944]

Thanx everyone that was helpful

[peter.mitchell]

you want absolutely minimal glue and best possible fit together.
generally you put some glue on your finger, gently smear it over the surface, wipe it off your finger on to some towel, then tightly press the ferrite back together, and hold it until it holds itself, then you put a bit of glue on the outside to support it - on the outside it is fine to add as much glue as you want provided it doesn't get in the way of the coilformer/bobbin.

[Arjan Emm]

I would use superglue because it is water thin and leaves the smallest airgap. Makes shure there are no loose bits on the surface so they fit as snug as possible.

[kavea]

Hi every one,
I was salvaging some inductors from old p.s.u and I accidentally cracked and broke one of the cores
Not meaning glue failure in an E type core but a real broken core ...

You can always glue it, BUT unfortunatelly it will decrease the effective magnétic permeability of your core since you will have some air gaps. So the inductance, if you have some wiring aroud the core will decrease.

[N2IXK]

You might want to consider a steel-filled epoxy like "JB Weld" or similar to minimize the magnetic discontinuity at the glue joints.

[rs20]

You can always glue it, BUT unfortunatelly it will decrease the effective magnétic permeability of your core since you will have some air gaps. So the inductance, if you have some wiring aroud the core will decrease.

If the core is an ungapped core, then yes, the decrease in inductance will be major.

However, if the core is already deliberately gapped, then there's every chance that the change in inductance will be negligible/within tolerance.

[Raj]

Fine Iron filled epoxy would be good, just clamp it firm, just enough for not to break it but to hold it together without any gap
Good Luck

[jorgemef]

Hello,

Just for comparison I am adding two photos for two cores I bought in Aliexpress. One came broken/cracked, and flux is in order of 10 times less.

Cheers,
Jorge

[jonpaul]

Very sorry cores are delicate céramique, so you cannot fix it, like a ceramic vase...

any glue creates an air gap, and the  glue loosening when power dissipating heats the core.

we just discard broken cores

j

[blackfin76]

Ferroxcube did some interesting test gluing E-cores with epoxy and acrylic based glues.
Epoxy glues come out as best but acrylic is also good.

Find the document in here