[vladimir1409]

Hi all,

the machine is Mori Seiki MV40V with Fanuc 0M-C control, 1990year,

few days ago we got some kind of vibration on the X axis,
the vibrations are with constant period along the whole length of travel,
there is no alarm the machine keeps on running but the vibrations from the X axis can be seen on the surface quality.

We check the bearing, they are fine the motor vibrates even when is out of axle,
we swap the servo control between the X and the Y axis, the vibration stays on the X axis,
we swap the motors between X and Y the vibration still stays on the X axis.

Has anyone had this kind of a problem, and any suggestion how to first find the problem and then solve it?

regards

[vladimir1409]

the motor is:
AC servo motor model 5S
type A06B-0314-B032

we also check the motor and encoder cables on problem there also.

[guhl]

what about backlash in ball nut?

[vladimir1409]

Thank you for your reply,
Problem existing even the motor is disconnected from ball screw. So any mechanical problem is out off any discussions for problem. We supposed that the problem is in CNC board (board that read encoder signal and send command to servo drive). We like to switch X control with 4 axis control but we do not know how to exclude X axis from the system.

[guhl]

X axis is a basic axis and I suppose you will not be able to exclude it from system
from the other hand, I think any trouble in feedback circuit causes "encoder disconnect" alarm
you may change GAIN in servo parameters and see how it influences

[vladimir1409]

there is no alarm the machine can work like this for hours,
and about the parameters we tried a lot of combinations and all we got is small differences even with drastic changing values
but the vibrations are still there.

We change the parameters 0269 to 2 and 0270 to 1 and we believe that the problem is coming from axis PC board A16B-2200-0360/03B
because the vibrations are following the M34/M35 conector...

Is it possible that this board is causing the problem?

[guhl]

did you swap power parts of drives (repeaters) or only PCBs?
are the interpolators (big black ICs) in sockets on A16B-2200-0360/03B? if so, you can swap them. really you can use soldering-iron for swapping

[tc429]

if theres anything in parameter 8121, i bet your coupling /setscrew/keyway is loose... set 8121 to zero and if vibration goes away its due to having load inertia comp with a loose torsional coupling.

running a uncoupled motor with load inertia comp'd can make it buzzy as heck.

if its a older ac servo with the black encoder under the red cap, pop the rubber plug out of the encoder and make sure the center bolt is snug- if the encoder is loose AT ALL on the tapered shaft, it will vibrate severely also.

[vladimir1409]

thank you for the reply

tc429 we tried that with the parameter 8121 to 0 the vibrations are still there,
we check even before the coupling and the center bolt of the encoder and we check again now there is nothing loose,
we even swap the servo motors so right now the motor from Y axis is on the X axis and vice versa,
we also swap the motor cables and the encoder cables result is the same vibration on X axis
that's why we suspected that the axis board A16B-2200-0360/03B may be bad especially because
the vibrations are by our opinion related to the M34/M35 connectors.
When we swap the parameter 0269 to 2 which means that the M34/M35 control the Y axis
and parameter 0270 to 1 which means that the M37/M38 cotrol the X axis,
the vibration goes to Y axis but stays on the M34/M35 conectors of the axis board.

this is why we think that the axis board is bad but we are not completely sure so if there is something else that we can try we are open for suggestions,
we can't try the axis board on other machine because there is no other machine in nearby with that 0m-C control to check for sure,
also we don't have fanuc service in our country so we would like to be sure as possible before we buy or pay for repair of the axis PC board.

we are open for suggestions if did something wrong so far or what to do next...

[CroCole]

Did u try to swap the motor servo drives ? U checked the motors, encoders and cables... Ony drives left.. If the error is in the same axis when u swap drives then it is the board (as u checked evreything else) if the error comes to another axis it could be the servo drive unit...

[vladimir1409]

the servo drives were the first thing among everything that we swap I wrote in the first post, and the vibration stayed on the X axis,
thanks for the reply

[tc429]

thank you for the reply

tc429 we tried that with the parameter 8121 to 0 the vibrations are still there,
we check even before the coupling and the center bolt of the encoder and we check again now there is nothing loose,
we even swap the servo motors so right now the motor from Y axis is on the X axis and vice versa,
we also swap the motor cables and the encoder cables result is the same vibration on X axis
that's why we suspected that the axis board A16B-2200-0360/03B may be bad especially because
the vibrations are by our opinion related to the M34/M35 connectors.
When we swap the parameter 0269 to 2 which means that the M34/M35 control the Y axis
and parameter 0270 to 1 which means that the M37/M38 cotrol the X axis,
the vibration goes to Y axis but stays on the M34/M35 conectors of the axis board.

this is why we think that the axis board is bad but we are not completely sure so if there is something else that we can try we are open for suggestions,
we can't try the axis board on other machine because there is no other machine in nearby with that 0m-C control to check for sure,
also we don't have fanuc service in our country so we would like to be sure as possible before we buy or pay for repair of the axis PC board.

we are open for suggestions if did something wrong so far or what to do next...

aah...last thing id try is physically swapping the cables that go from m34/35, just in case a cable/connector has a ground fault/busted wire, etc...switch the cables completely- at the axis card and at the drive- just to isolate the cable...if no change, physically remove motor wires from drives, swap x<>y, AND swap command cable at only one end from x<>y so the motor and command get moved to another drive . if you can switch things around, should be able to verify where problem lies- drive typically more common failure than AXE card...good luck

[CroCole]

Does your machine have 4th axis output on A16B-2200-0360/03B card... Do u use the 4th axis? If u have that output and u dont use 4th axis output then u could set the X axis cables (M34/M35) to 4th axis and set the parameter to use the 4th axis output to drive the X axis... (Then swap the parameters 272 and 269 to set the output to that cables)

[vladimir1409]

CroCole; Yes I have a 4th axis output on A16B-2200-0360/03B card and I don't use it, I tried your suggestion but I keep getting alarms,
I also tried different combinations no luck again, this is what I've tried:
269.......4 / 0 / 0 / 4
270.......2 / 2 / 1 / 1
271.......3 / 3 / 2 / 2
272.......1 / 1 / 3 / 3
In every other combinations of parameters than 269=0,270=0,271=0 and 272=0 or 269=1, 270=2, 271=3 and 272=4 I keep getting servo alarm 400 and 4n7 which means that the axis selection parameter(No 269-274) is incorrect. When we were trying the combinations we took care that the connectors on the axis board comply with the axis selection parameter just to be clear. I have a servo drive and all the connector cables for the 4th axis but don't have a 4th axis or motor to plug at the end of the motor cable and encoder cable, also there is a switch on the cabinet to use or not to use the 4th axis. In either position on/off the alarms are there.

tc429; we tried your suggestion, first swap the cables completely as you said on the axis card and on the servo drive, no changes there, conclusion cables are ok.
then swap the motor wires from drives and command cables at one end, the vibration now goes to Y axis but it stays on the M34/M35 ports, conclusion axis boar ports M34/M35 has fault or we are missing something?!?

[tc429]

hmm...only real issue ive seen on AXE cards was had a few with the square axis LSI chips not seated correctly, and had one that the socket had split in a corner, causing intermittent contact to some pins -cheated and fixed by removing chip wrapping string around socket frame and epoxy coating...still running, but ugly

might try simply reseating the two axis chips, about half the time if you press then firmly they will 'click' another .020 or so deeper in to the sockets...many you can see are crooked in the sockets from fanuc. while its out, look closely for trace corrosion- the double stacked plugs/plastic board frame was a stupid idea - the weight always 'bows' the card, curving it causes tension on rear traces... if a trace fails, usually there will be a 'bubble' around a trace where clear coating heated up. ohm check across any of those, if you find one open, gently scraping the coating off, bridging with solder/strand of wire usually works. look REAL close at the little address chips close to the rear board connector- those get corrosion and all kinds of weird stuff happens. a buddy that does a lot of fanuc repairs showed me how he cleaned boards, just soak it with Fantastik/409 and gently scrub with a soft paintbrush, blow off and let it dry (baking with a hairdryer wont hurt)... a LOT of boards can be 'fixed' just by cleaning.

do not let anyone use 'simple green' or 'ultra blue' or any other industrial degreasers to clean boards- a yr down the road cracks in the plastics, and yellowish corrosion always pops up. never ever had any issues with Fantastik or 409 cleaners.

[vladimir1409]

thank you tc429, we will check closely for trace corrosion and will do ohm inspection as much as we can do, but while we do that just interested in the suggestion of CroCole:
"Does your machine have 4th axis output on A16B-2200-0360/03B card... Do u use the 4th axis? If u have that output and u dont use 4th axis output then u could set the X axis cables (M34/M35) to 4th axis and set the parameter to use the 4th axis output to drive the X axis... (Then swap the parameters 272 and 269 to set the output to that cables)"

I do have the 4th axis ports, we were wondering can it really be done maybe we did something wrong or something we missed, I also read somewhere that if I use the 4th axis ports that we can not use interpolation tool offset etc.

please confirm if anyone have done this and manage to work...

[drdos]

As far as using the 4th axis goes, that is a Fanuc paid option. So chances are good you don't have that port active. I would buy a new board and be done with it.

[vladimir1409]

drdos; thank you for the reply i think I have the 4th axis option, I also have the servo drive and all the cables for the 4th (A) axis up to motor and encoder connector built in the machines cabinet, I only miss the executive element. I also have a switch on the cabinet that turns on/off the system requirement to search for the 4th(A) axis zero point signal and to display the A coordinates, also there is a switch on/off 4th axis neglect, so I am pretty sure that I have the 4th axis option.

And yes I did ordered another axis card a repaired one because there isn't new at least that is what they told me, but it will be here in two weeks time so I would really appreciate if you have some knowledge and suggestion how to swap the axis ports on the axis card and get it to work...

If you need some details about the machine parameters or something else, it's no problem I can easily provide them to you or post them here.

regards

[drdos]

1st question, does this machine have scale feedback? (Separate from the motor) Set Parameter 269 to 4 and set parameter 272 to 1 Move the cable that is plugged in M34 to M47, move the cable that is plugged in M35 to M48. If there are any cables or dummy plugs on M47 or M48 they must be move to M34 and M35 respectively. IF you have scale feedback on X axis you will also have a cable plugged into connector M36, that will have to be moved to M49.

Hope this helps

[TechnicalRepair]

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