Re: [CAD_CAM_EDM_DRO] A little experiment on demagnetization

PS forgot to mention that remagentising motors is a very specialised task.
You need to produce a very high and precisely shaped flux pattern. This
requires a fixture for each type of motor that carries a winding and a
magnetiser to produce the very high short duration current pulses.

Regards Peter

----- Original Message -----
From: <mariss92705@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, February 04, 2003 4:45 PM
Subject: [CAD_CAM_EDM_DRO] A little experiment on demagnetization


> Hi,
>
> When I don't know for sure, I run an experiment:-)
>
> 1) I took two identical motors, (Rapidsyn 23D6209, 4.7A @ 1.7VDC)
> connected in full-winding mode and set the current to 2.4A per phase
> on a G201. The power supply was 25VDC.
>
> 2) I removed the rotor from one motor, waited 5 seconds, then
> replaced it. The other motor was unmolested and would serve as the
> baseline unit.
>
> 3) Both motors were then run on a dyno and data was taken at 5 revs
> per second (1,000 full steps per second).
>
> 4) The baseline motor delivered 18.25W to the dyno at that speed for
> a torque of 82.3 in-oz.
>
> 5) The molested motor delivered 11.75W for a torque of 52.9 in-oz.
>
> 6) The calculated torque (and power) output for the disassembled
> motor was 64% of the intact motor.
>
> 7) I removed the rotor again, leaving it out overnight before
> reassembling it for the second time and ran the above tests again.
> There was no additional deterioration in performance.
>
> Conclusions:
>
> 1) Demagnetization occurs immediately on disassembly.
>
> 2) The motor loses about 1/3 of its holding torque and and power as a
> consequence.
>
> This experiment applies to standard magnet motors. I have not tried
> it on the newer, rare-earth magnet motors. I like the ones I have too
> much to find out. Any volunteers?
>
> Mariss
>
>
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