X Axis Bearings.. Motor Vibrating..

[coop31]

Had the seals go bad on my x axis thrust bearings, and had to replace the bearings. Got it all apart, ordered new parts, put it back together. Everything seems fine until I move ...

The motor is vibrating back and forth really fast making a humming noise. I assume I had something too tight, so I loosened a few thing up, but the issue is still there.

Any ideas? Machine is a Arrow II1250c with Siemens drives and motors.

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[JordanMach]

I had the exact same issue when I first got my machine. I had to download Simocommu? to access the servo drives, and "de-tune" the drives a bit. I actually tried doing it myself, but didnt know what settings to change. I had a Siemens tech come out and do it for me. But I downloaded the before and after tunes of the drives so i know exactly what settings he changed. If you feel comfortable doing this, I can give you my factory, before, and after tunes so you can see what changes were made to my drives and what changes you may need to do to yours.

[meckardt55]

Do you have scales for the position feedback?? Did the end of the ballscrew have a weight attached to it??

MIKE
CNC Machine Services INC | Cincinnati Milacron MachinesCNC Machine Services

[coop31]

Do you have scales for the position feedback?? Did the end of the ballscrew have a weight attached to it??

MIKE
CNC Machine Services INC | Cincinnati Milacron MachinesCNC Machine Services

Yes, machine has scales in x and y. There was no weight on the screw.

[coop31]

I had the exact same issue when I first got my machine. I had to download Simocommu? to access the servo drives, and "de-tune" the drives a bit. I actually tried doing it myself, but didnt know what settings to change. I had a Siemens tech come out and do it for me. But I downloaded the before and after tunes of the drives so i know exactly what settings he changed. If you feel comfortable doing this, I can give you my factory, before, and after tunes so you can see what changes were made to my drives and what changes you may need to do to yours.

Yes, I would be interested in checking that out. I've had the drives hooked up to the computer when I first got the machine, hopefully I can dig up the cable.

[coop31]

Jordan, I've got everything set up and waiting for your files. I sent you my email address in a private message.

[JordanMach]

I did get you PM. I am trying to figure out if I downloaded the After tune files or not. I have the factory files. And I have downloaded files.... I have to compare them now to see if those downloaded files are from before or after the tune. Ill do that right now. Give me some time.

[JordanMach]

Coop, I sent you 2 emails. One with the parameters and one with a PDF comparing the parameter changes side by side. I Hope this helps.

[maver1ck]

I have never had to tune the drives to fix a mechanical issue in these machines. Doing so may mask the problem so you don't notice it, but it is not fixing the actual problem.

Do you have the assembly back together properly? There is a spacer that is to be ground to fit at assembly, it shouldn't need to be re-ground if all you did was replace the bearings, but may be worth checking.

Since you have scales on this machine you could be looking at a feedback issue too, but if it only started when replacing the bearings I'd start by looking at mechanical issues first.

Cincinnati used a series of weights to dampen harmonics on many of the machines, I have seen a few cases where these fell off (or were removed by someone who didn't know what they were for). Check your prints to see if they should be on the machine.

[JordanMach]

When talking with the Siemens tech and also FIVES about my issue. I heard that this is not the most uncommon issue. Over time the ball screw wears out ever so slightly, and everything else. AND the Siemens drives are tuned to 110% performance that if the mechanicals are only at 97% performance you will get this issue. I think my ball screw has a bow in it of about .0005" in the middle. That is more then likely what is causing my issue, but is not ground for replacing or repairing the ballscrew. Just the slight harmonics of the mechanicals will throw the motors and drives into that loud buzzing (dither). I have had no ill effects from de-tuning my drive. I see nothing wrong with it. It's an old machine I got for next to nothing, and don't plan on dumping money into it as it's making me a ton of money as it sits now.

[coop31]

Yes, exactly. These forums have helped me big time in the 6 and a half years I have been in business for myself. I have gained lots of knowledge, and hopefully have helped a couple other members along the way.

Jordan's files got me back up and running. Is it the perfect solution? I don't know, but the machine is running making money as I type this.

Thanks again for the help Jordan.