[camaro_dan67]

I have a Kiwa Excel center-4 with the 3m-c control. I had to replace the z axis dc servo motor model A06B-0642-B011. After replacing the motor the movement is ok but the motor is making a squealing or squeaking sound when sitting still. The sound is not that loud, just noticeable. I'm afraid if I don't do something about the sound it might damage the motor or motor drive. Thanks everyone. Dan

[oetkbyentc]

Not much tuning to be had on a DC servo.
Provided you are sure of the mechanical installation and no changes or disturbances were made to wiring or cable routings. There are 2 pots to look for on the drive. One is Gain. The other may be labeled Dither or Offset.
Use these in conjunction with the position error diagnostic to stabilize the servo at rest. The adjustments should be very small as the system was stable prior.

[camaro_dan67]

How do I do the adjustment with the position error diagnostic? Will this be a number that is constantly moving and I am trying to settle the movement? Or am I trying for a certain number in the diagnostic?

[oetkbyentc]

If you are hearing vibration it will be constantly moving. 1st step would be to stabilize the the value. 2nd step would be to bring it to as near zero as possible at rest.

The pots may also be labeled RV1 RV2 etc. RV1 should be gain and RV2 would be offset. But I would recommend checking your manuals to confirm.
Gain would be my 1st choice to stabilize the system. Then offset to get near zero if needed.
These adjustments assume no scales.
I think the diagnostics are in the 800 area. Its been a while since I have seen a 3M control sorry I cant be more detailed.

[camaro_dan67]

If you are hearing vibration it will be constantly moving. 1st step would be to stabilize the the value. 2nd step would be to bring it to as near zero as possible at rest.

The pots may also be labeled RV1 RV2 etc. RV1 should be gain and RV2 would be offset. But I would recommend checking your manuals to confirm.
Gain would be my 1st choice to stabilize the system. Then offset to get near zero if needed.
These adjustments assume no scales.
I think the diagnostics are in the 800 area. Its been a while since I have seen a 3M control sorry I cant be more detailed.

Have you done any of this type of tuning with an oscilloscope? I have a 100mhz 2 channel unit available for use. Using the scope would be more accurate wouldn't it?

[oetkbyentc]

I have done the adjustment many times. No scope needed. I don't usually see this type of issue arise from a servo swap vs. a drive swap.
The axis positions properly otherwise?
Performance in general seems ok?

[camaro_dan67]

I have done the adjustment many times. No scope needed. I don't usually see this type of issue arise from a servo swap vs. a drive swap.
The axis positions properly otherwise?
Performance in general seems ok?

I have not done any position testing just rapid moves and some jogging with the handwheel. I was afraid to run it to long thinking it might mess up the drive. Do you have documentation on how to adjust it? Or should I simply mark the original gain position and try to do slight adjustments?

[oetkbyentc]

Go with marking current position and then make small changes. The adjustment should be pretty small. After some adjustments to the gain pot both cw and ccw, if there is no change in performance you may need to look at other areas.
Depending on where the replacement servo came from it could be suspect. Motor part number is identical? Does the motor have a tach or encoder? If its an encoder is it the same part number (2500/2000 ppr) as original?

[camaro_dan67]

Go with marking current position and then make small changes. The adjustment should be pretty small. After some adjustments to the gain pot both cw and ccw, if there is no change in performance you may need to look at other areas.
Depending on where the replacement servo came from it could be suspect. Motor part number is identical? Does the motor have a tach or encoder? If its an encoder is it the same part number (2500/2000 ppr) as original?

The motor and encoder are identical part numbers as far as I know. I didn't pop the cap off of the back of the motor to double check the part number on the encoder.
I tried turning the gain pot ccw about 1/8 turn. It greatly reduced the whine sound. I could still faintly hear it if I put my ear about a foot away from the motor. I also did a slow jog feed up and down with the z. It made the same faint whine sound while feeding but didn't sound much louder then most of the cnc machines I've used through the years when they were in a slow feed. Should I adjust more or leave it alone?

[oetkbyentc]

Look at the Diagnostic and see what it looks like. Usually a swing of 2 to 3 units is what I shoot for depending on axis type (vert/horz). Then you may need to adjust offset to get closer to 0 if its not already there.

Fanuc servos are whiney buggers in general. The diagnostic is the true indicator.

[camaro_dan67]

Look at the Diagnostic and see what it looks like. Usually a swing of 2 to 3 units is what I shoot for depending on axis type (vert/horz). Then you may need to adjust offset to get closer to 0 if its not already there.

Fanuc servos are whiney buggers in general. The diagnostic is the true indicator.

I'm not sure on my machine which diagnostic I need to look at for this. I do have the maintenance manual that covers some parameters and diagnostics. I'll have to take a good look at it.

[camaro_dan67]

I'm not sure on my machine which diagnostic I need to look at for this. I do have the maintenance manual that covers some parameters and diagnostics. I'll have to take a good look at it.

Ok in the book I found diagnostic number 802 says it displays the position deviation amount for the z axis. Does this sound like what I should be looking for?

[camaro_dan67]

Ok in the book I found diagnostic number 802 says it displays the position deviation amount for the z axis. Does this sound like what I should be looking for?

Tonight I did adjusting using my diagnostic numbers 800 to 802. 800 for x, 801 for y and 802 for z. I started with adjusting the gain on the z servo drive I got the number close to 0 but it was still jumping up and down. Next I went to the offset pot to get the fine adjustment. I got it to the point where it would jump between 0 and 1 about every 3 seconds or so it may have been more time then that. I repeated the same process for the other 2 axis. After that the z motor seemed fairly quiet.

[oetkbyentc]

Run it and see. Check motor temp after a bit and make sure it is not running overly hot. Double check positioning. After that sounds like you are set.

[camaro_dan67]

Run it and see. Check motor temp after a bit and make sure it is not running overly hot. Double check positioning. After that sounds like you are set.

I ran it for a while this morning. Mostly just drilling holes so no accurate position checking yet. I had it going about 45 minutes and before I shut it down I put my hand on the motor and it was cool to the touch.
I'm thinking I need to add an oil seal to the motor shaft because the motor I took off the machine actually pulled oil into it from the gearbox.

[oetkbyentc]

Per Fanuc
"Models 00M, OM and 5M are provided with oil seal as the standard equipment. In case of Model 10M -
30MH, order the following oil seal flange, if the oil seal is required.
Oil seal flange (option): A290-0601-T901 (For outline drawing, see the next page.)"

Its basically a 12mm thick plate that duplicates the motor flange. It has a boss and pilot to go inline with the servo. It has a bore to accept a AC2057A0 seal.

[camaro_dan67]

Per Fanuc
"Models 00M, OM and 5M are provided with oil seal as the standard equipment. In case of Model 10M -
30MH, order the following oil seal flange, if the oil seal is required.
Oil seal flange (option): A290-0601-T901 (For outline drawing, see the next page.)"

Its basically a 12mm thick plate that duplicates the motor flange. It has a boss and pilot to go inline with the servo. It has a bore to accept a AC2057A0 seal.

Thank you I will look into that.