Re: [CAD_CAM_EDM_DRO] hot servo motors, heatsinks??

Hi etauch;

As in all thing in life it depends.

You didn't mention what type of servo motors you have. If they are
plane old permant magnet motors then you have to be very carefull.
Excessive heat WILL demagnitize the magnets.

As far as heat removal I've seen fans and water jackets added to AC
servo motors. Obviously these have a differrent failure mode with
heat. The reality is that you are going to have to take temperature
reading of the case to remove the subjective and then check with the
motor manufacture. Your motor could be very well undersized or your
mechanics could be bound up or your just driving them to hard. The
description you paint below indicates to me that you do have issues that
should be resolved.

Brushless servos and steppers are often designed to operate with much
higher case temperatures, so I'm hoping we are not confusing the issue
here. In any event there is nothing like the manufactures
documentation to set in stone the permissable operating parameters.

Dave


etauch wrote:

>Greetings,
>
>I am currently at the point where I am testing my CNC
>conversion. I notice that the servos get quite hot
>after about 5 min of running. Not so hot that I cant touch
>them, but if you grab one, you can only hold on comfortably
>for a few seconds.
>
>I know they are running at low RPM, so this is probably one
>of the causes (higher I^2R at low rpm?). Also, I am dumping
>many amps into a relatively small mass, so heat is to be
>expected.
>
>My question for those with experience with CNC servo motors.
>Does anyone install heatsinks on them?? At what point should
>you shut down to let them cool off? I think they are ok
>after 5 min, but if I were chugging away on something for 30 min
>or so, I think they might burn up.
>
>Some info on my setup...
>This is a HF 47158 micromill with 190 oz/in servos
>using direct drive (bracket and shaft couplers). I am
>running a Camtronics/Gecko320 servo driver box, and also
>installed a 20lb gas spring to offset the head weight on
>the Z screw.
>
>
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