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magnets in steelcasing
By Stonebrain, Section Mechanical Posted on Sat Sep 9th, 2006 at 08:46:50 AM MST
what about these

I found this item on the site of neotexx(germany)

(dimensions are in mm,there are smaller ones too.
A rough estimatio of me is that you pay about double for the same magnetic material
There might be some losses of flux,because of the steel on the sides of the magnets.
Say,it tree times more expensif for the same magfnetic fflux.
But wouldn't it be worth the price for good fixing and long lasting rotors?
cheers,
stonebrain

magnets in steelcasing | 6 comments (6 topical, 0 editorial)

Re: magnets in steelcasing (3.00 / 0) (#1)
by Norm (peppysue@suite224.net) on Sat Sep 9th, 2006 at 06:24:22 AM MST
(User Info)

I think something similar has been posted.
These make very good magnets for picking up stuff
...the ring of steel would be one pole and the
center would be the opposite pole.....
( :>) Norm.
( :>) Norm

Re: magnets in steelcasing (3.00 / 0) (#2)
by Stonebrain on Sat Sep 9th, 2006 at 07:33:13 AM MST
(User Info)

I don't know what you mean.
These ones are magnetised trough the 15 mm like
the usual ones.

[ Parent ]

Re: magnets in steelcasing (3.00 / 0) (#3)
by Flux on Sat Sep 9th, 2006 at 08:35:07 AM MST
(User Info)

Yes they are pot magnets designed for holding and lifting.

If you use them as normal magnets the steel pot is shunted directly across the magnet path and will divert a lot of the useful flux. I suspect they are not even neo, that would be an expensive way to make neo pot magnets, you could get the same result with a thin neo disc and a centre steel pole.

If you think of the centre as a N pole the outer steel ring will be a S pole and the flux will pass from the centre to the ring by the shortest route.

[ Parent ]

Re: magnets in steelcasing (3.00 / 0) (#4)
by Stonebrain on Sat Sep 9th, 2006 at 09:24:05 AM MST
(User Info)

"I suspect they are not even neo, that would be an expensive way to make neo pot magnets, you could get the same result with a thin neo disc and a centre steel pole."

wrong

" Pot magnet with hole 60 x 15mm
NdFeB Magnet with a steel casing
Dimension: do60 x di8.5/15 x h15mm with hole
Magnetized Direction: through 15mm
Attraction Force: about 95kg
Surface: Steel
Max. Operating Temperature: 80°C
item # PM-000B60

Delivery within 1-2 days"

My question is: how much flux will be lost through the casing? 10%? 30%? 50%?

I don't say it's a good choice,I don't even know if they have them both with N on
top and S on top and they doesn't mention what grade it is.

The only thing I think that compare to the usual casting and the troubles it gives
very often,this one fixed with a screw will be undestructable.

MAybe thats not their intended use,but what do I care about that.

cheers,
stonebrain

[ Parent ]

Re: magnets in steelcasing (3.00 / 0) (#5)
by Flux on Sat Sep 9th, 2006 at 09:52:11 AM MST
(User Info)

How much loss - who knows? depends on your design and air gap. Rough guess 80%

If you want to use the things then machine the pot off beyond the air gap that solves the problem.

I doubt that you have any choice with polarity. You will likely have to mount half of them backwards and accept that you have a mild steel pole piece in half the gaps.

Flux

[ Parent ]

Re: magnets in steelcasing (3.00 / 0) (#6)
by Stonebrain on Sat Sep 9th, 2006 at 10:32:01 AM MST
(User Info)

Flux,

I appreciate your efford to scare me from making stupid choices.

Thanks a lot,

cheers,
stonebrain

[ Parent ]

magnets in steelcasing | 6 comments (6 topical, 0 editorial)

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