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VMC Multiple X axis / ballscrew problems

Check the jumpers on the amplifier. Compare the placement of them on the X and Y amplifiers. We had an issue with a machine jumping and making vibrations while the Y-axis was moving. Initially we thought bearings and ballscrews too, turns out two of the jumpers were in the wrong orientation and it wasn't set for the number of pulses the encoder uses. It was reading for more pulses than were actually being generated. If you send the amplifier out, they won't find anything because, it is working the way its designed to, just not the way it is supposed to with your specific machine.
Hello , could you help me with these , I am not sure about these jumpers you refer to as the cables can go only 1 way?
 
Check the jumpers on the amplifier. Compare the placement of them on the X and Y amplifiers. We had an issue with a machine jumping and making vibrations while the Y-axis was moving. Initially we thought bearings and ballscrews too, turns out two of the jumpers were in the wrong orientation and it wasn't set for the number of pulses the encoder uses. It was reading for more pulses than were actually being generated. If you send the amplifier out, they won't find anything because, it is working the way its designed to, just not the way it is supposed to with your specific machine.

Does this apply to a modern Fanuc amp? I thought basically everything was set by parameter on those?
 
Hello ,

I am not sure if we can call it modern as it's 22 years old machine , even if it's still in a good overall codition.
 
Hello,

I will have Fanuc in next week to do other things on other machines , I will ask them , however if anyone else has other ideas , I would like to know.

Also I kept trying, I can change backlash parameters but they don't make any changes on any axis which seems strange.
 
Does this apply to a modern Fanuc amp? I thought basically everything was set by parameter on those?
Apologies, I missed the model of controller. I have Fanuc 15M and older control systems on some of our machines, but the 16iM goes to the new style boards and amplifiers with digital everything. But the principle may still apply. I assume there are parameters for puslecoder feedback rate, compare the parameters of X and Y amplifiers. Isn't it possible that a parameter was accidentally changed, or the amplifier replaced, before you got the machine and never set to match the servos your machine uses?
 
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Apologies, I missed the model of controller. I have Fanuc 15M and older control systems on some of our machines, but the 16iM goes to the new style boards and amplifiers with digital everything. But the principle may still apply. I assume there are parameters for puslecoder feedback rate, compare the parameters of X and Y amplifiers. Isn't it possible that a parameter was accidentally changed, or the amplifier replaced, before you got the machine and never set to match the servos your machine uses?
I believe those settings would be within the control. Not entered at the AMP. I've swapped plenty of amps and the only ones I've ever had to enter parameters Into were older Spindle Amplifiers. And I have both versions of servo amps here. The ones that do have jumpers it is Important to verify that those are correct. But as gregormarwick stated above. The newer models are all enclosed and there are no jumpers present.

Just because the AMP was tested and throws no alarms doesn't convince me that there Isn't a problem with It. Who tested It? How extensively did they test It? All testing and repair outfits are not equal. I know from experience. Some Bad. If the problem follows the AMP, well what else would you think the problem was? The first thing I would do Is swap that AMP.
 
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I think there are parameters to possibly tune the servos, but I am not sure what to change?

I am also tented to buy another refurb amplifier , but if the problem is related to servo tuning , I will put another probably at least $1000 down the toilet
 
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I think there are parameters to possibly tune the servos, but I am not sure what to change?

I am also tented to buy another refurb amplifier , but if the problem is related to servo tuning , I will put another probably at least $1000 down the toilet
Who are you buying your parts from?

It's not putting your money down the Toilet. Worst case you have a spare AMP.
 
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It's a local electronic refurbishing company, specialising in Fanuc parts.

Do you think is too expensive or too cheap?

Also I am not sure if parameters re-tuning would still need it?
 
It's a local electronic refurbishing company, specialising in Fanuc parts.

Do you think is too expensive or too cheap?

Also I am not sure if parameters re-tuning would still need it?
I have never re-tuned servos after changing an AMP. Although It might not be a bad Idea I don't think that's your problem unless something Is way out of wack. Somebody more knowledgeable than me like Vancbiker might have a better answer to that.

Tell us who. TIE, Industrial Automation?

$1,000 is pretty cheap. Especially for an already refurbed AMP. If your sending one In for repair that might be closer.
 
Do you have the maintenance manual? I believe it is B–63005EN/01. If that is the case you can find it online, free PDF. Section 5 is servo parameters and tuning. Might be worth looking into
 
I have never re-tuned servos after changing an AMP. Although It might not be a bad Idea I don't think that's your problem unless something Is way out of wack. Somebody more knowledgeable than me like Vancbiker might have a better answer to that.

Tell us who. TIE, Industrial Automation?

$1,000 is pretty cheap. Especially for an already refurbed AMP. If your sending one In for repair that might be closer.
It's DNC electronic , the price is for a refurbished one in exchange of the old one.
 
It's DNC electronic , the price is for a refurbished one in exchange of the old one.
I have no experience with them so I can't comment on that. I'm sure others here have used them. $1,000 is pretty cheap from my experience. That doesn't mean they don't know what they're doing by any means. If you've used them In the past with good results then ok.
 
It's a local electronic refurbishing company, specialising in Fanuc parts.

Do you think is too expensive or too cheap?

Also I am not sure if parameters re-tuning would still need it?

If you are questioning the amp that you sent out for testing - I might try a different source for the replacement unit.

I also agree that it sounds like it might somehow be within your amp.

-----------------

Think Snow Eh!
Ox
 
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hello guys, just an update.

this might be helpful for someone else with the same problem in the future.
So I had the x-axis ballscrew re-balled ( it was sent out ), but the problem was still there although no more mechanical problems, we then found a set of parameters that are not even on the Fanuc Book, but under the "miscellany" section, when we tweaked these, we could compensate for the shock/backlash problem we had.

I have just had the y axis ballscrew re-balled as well.

We put back values very close to factory settings now.

This is the first Fanuc-controlled machine I have and the first Fanuc-controlled machine that I have used which ignores backlash comp value in parameter 1851 but refers to another group of parameters for backlash comp.
Possibly an odd configuration from the MTB??

Anyway, in this case, the problem has been resolved.
 
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Hello,

In my particular case they were from 6870 to 6875 , not sure why 5 parameters, but this is what I have.

Miscellany parameters numbers might be different based on the Fanuc control model.I think
 








 
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