Re: Mysterious Answers Demagnetized !

Thank you again Mariss,

Seems your tenacity to getting your questions answered makes you more
knoledgable, but then your knoledge spread around makes us smarter
too !

On behalf of the list, we all thank you.


Dave

--- In CAD_CAM_EDM_DRO@y..., "mariss92705" <mariss92705@y...> wrote:
> Hi,
>
> Ok, I just flew in from San Jose from my visit to Lin Engineering,
a
> manufacturer of very high grade step motors. I asked the question
> regarding motor de-magnetization and I got an unexpected answer
from
> their cheif motor magnetics designer.
>
> It seems demagnetization of the rotor depends on motor frame size.
> It's OK to disassemble a size 23 or smaller motor. DO NOT try it on
a
> frame 34 or 42 motor though.
>
> The thing that makes the difference is the rotor tooth spacing. The
> teeth on a size 23 motor are close enough together that the flux
path
> from tooth to tooth is enough to act as a magnetic "keeper". The
> larger motors do not enjoy this advantage and WILL demagnetize if
> removed from the stator.
>
> I got enough magnetics equations to completely agree with their
> conclusions. To add to that, there were several tales of
accidentally
> removing rotors from stators from size 34 motors that required
> emergency runs to a facility that magnetizers big enough to restore
> the rotor magnetization so that orders could be met.
>
> On a side note. Their on-site size 23 motor magnitizer is a 4' by
4'
> by 6' piece of equipment. The meters on it are sobering; 100A at
> 1,000V. That's a lot of power. All discharged into a water-cooled
> coil about 6" OD, 3" ID.
>
> They said someone a few years ago entertained themselves during
lunch
> by putting 6" nails in the magnetizing coil and pushing the "go"
> button. The nails went thru the drywall ceiling 12' above and
> embedded themselves in the 2X8s as if they had been nailed with a
> hammer. The original magnetic rail gun I guess. Impressed me; fun
> day, learned things I didn't know before.
>
> Mariss