Re: [CAD_CAM_EDM_DRO] Why do stepper motors lose their magnetism when disassembled?

HI Phil,
I've heard 2 ways that steppers lose their magnetism.
First has to do with the amount of current flowing through the stator windings.
I think if it goes beyond a point it will cause the magnetism to decrease,
and I think it can happen in a dynamic braking condition. From what I've
heard it affects PM servo motors in the same way.
Second, if you dismantle a stepper and take the rotor out of the stator it
will decrease the magnetism because the rotor acts as a keeper for the
magnetic condition of the stator. Perhaps if the rotor is slid out of the
keeper as a keeper is being slid in it will be OK. Maybe others would care to
comment, I've never tried it. I have taken end bells off to expose the bearings
and mount electrical junction boxes, but none of that required taking the
rotor out of the stator.
cheers,
Denis

On Friday 12 December 2008 09:32:00 Yahoo wrote:
> I've often heard this warning (after finding out for myself the hard way)
> but have never seen an explanation why.
>
> Any takers?
> --
> Phil Mattison