Mazak Noisy X axis

johndib · Jan 15, 2018

Have an old Mazak 7.5 mill that's making noise in the X-axis. Wondering if there are any bearings or ways that are worn. Is there any where online to get a parts breakdown for the machine? I haven't called Mazak yet.

MJPfin · Jan 15, 2018

Most likely thrust bearings.

Marko

FJV25 · Jan 16, 2018

We have an FJV25 from 1998 and it was making som noise on x axis and we thought it was mechanical, but it turned out to be the servo drive for the x axis.

Scruffy887 · Jan 16, 2018

Usually thrust bearings but in my case, big friggin ballscrew. About 8 foot long. It was not getting lubrication for the last ten years and finaly started overloading the drive. Replaced it along the bearings and all is well. Except for that hole in my wallet.

aj · Jan 16, 2018

If it makes the same noise in both directions it may be the ball screw. Try de-energizing the drive and turning the ball screw by hand. If it feels 'grumbly' in both directions it's probably the ball screw. If it feels rough in only one direction it may be thrust bearings. If it's smooth in both directions it may be as FJV25 says, a drive problem.

Vancbiker · Jan 16, 2018

One test I have found helpful on longer screws is to listen to the pitch of the noise. If the pitch goes lower in the middle of the travel and higher at the end(s) it is usually the screw/nut assembly. If the pitch is constant through the travel then it is usually the thrust bearings.

johndib · Jan 16, 2018

The noise seems to be coming from the left side of the table which is where the servo is located. Took it apart on that side and there are two tapered bearings stacked side by side. They feel fine but I ordered two new ones and will see if that stops it.

johndib · Jan 18, 2018

Changed bearings. Still noisy. Could it be the ways or wear guides on the table if there are anything like that?

johndib · Jan 18, 2018

The ball screw turns with no noise. The servo motor spins by hand and sounds fine. But when you power it to move it back and forth you get the noise. And sometimes it kicks a 411 X servo code. Could the servo motor be bad or going bad and making a noise like that when power is applied to it?

Vancbiker · Jan 18, 2018

johndib said:
.....And sometimes it kicks a 411 X servo code.

Ought to post the control model.

MJPfin · Jan 19, 2018

To me that sound like the ways, or encoder problem, but hard tell from the video.
Take a long steel rod and put one end against your ear and use the other as a makeshift endoscope to listen to the servo and other parts of the frame to pinpoint where the sound is loudest.
Long screwdriver works as well.

Marko

gregormarwick · Jan 19, 2018

That sure sounds like a servo fault rather than a mechanical one. I went through this last year with an older Yaskawa AC servo - an encoder fault that would alarm out eventually but made terrible banging noises in one direction while it ran.

Scruffy887 · Jan 19, 2018

Another possibility is the drive freeking out cuz it is ready to give up the magic smoke.

johndib · Jan 20, 2018

It's a Fanuc 6MB. It's definitely not something in the ways or table. I can turn the ball screw by hand and no noise back and forth. The noise comes from the servo motor when you go back and forth with it. I took the brushes out and not much in there to clean but I sanded the brush face a little and try to blow out any dust (not much you can get to). Put motor back in and it sounded quieter for a second or two and then got noisy again. Then it kicked a 400 code. Ever hear of noises like that from a servo motor? Thinking about finding a replacement motor if I can. If I find a motor, is it a direct bolt-in and not have to do anything to codes or something?

Vancbiker · Jan 20, 2018

You would need to verify the replacement motor had the same encoder as the original. There are different pulse per rev counts on the encoders.

You can try swapping X and Y motors to see if the trouble follows the motor. Z is often a larger motor than X and Y so not as good a candidate to swap with.

MJPfin · Jan 21, 2018

Oh it was a brushed servo, definetly then sounds to me that its encoder problem.
All the brushes move ok and no visible arcing on the collector? One short brush could cause that kind of behavior.

Marko

Roooster · Jan 21, 2018

If it has a tach in the motor, see if you could clean the commutator. Also check the continuity of the windings in the tach.

Milacron · Oct 5, 2021

aj said:
If it makes the same noise in both directions it may be the ball screw. Try de-energizing the drive and turning the ball screw by hand. If it feels 'grumbly' in both directions it's probably the ball screw. If it feels rough in only one direction it may be thrust bearings.

I've got a VMC where the X axis is noisy equally in both directions. And yet the backlash is only .0001" so I find it hard to believe the ball screw is worn. Are thrust bearings still the likely culprit if equally loud in both directions ?

Mazak Noisy X axis

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