Re: A little experiment on demagnetization

Hi,

An addendum to the previous post. Something bothered me about the
data. The motors I used for the test came from a very nice 4" X,Y
table I got from Tim Goldstein made by New England Associates
Technology.

Both motors had been modified by NEAT so that the wires came out the
front of the motors rather than the rear as is usual. That is the
reason I didn't want the motors after I re-motored the table with
some really nice Vexta PK268-03A "square" motors (sorry Tim).

The thing that troubled me was 82 in-oz is low for that motor.

I looked thru my vast motor harem until I found another 23D6209
motor, this time with conventional leads.

I ran the same setup on this motor and got 23.5W at 5 revs per second
for a torque of 106 in-oz. That is more in line with what I would
expect for that motor.

I would conclude both motors had been partially disassembled (and
demagnetized) to make the wiring modifications. The actual torque
loss is more like 50% rather than 33% when compared to a know good
motor (106 in-oz vs. 53 in-oz).

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mariss Freimanis
<mariss92705@y...>" <mariss92705@y...> wrote:

> 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