Spindle Gear Noise

[IMtech]

So, our Toyoda FV45 had been getting a bit louder lately to where it sounds like an almost grinding noise coming from the spindle gearbox. It finally got to the point where we had to stop using the machine for fear of completely destroying the machine. It has been taken apart multiple times since then (replaced all of the thrust bearings on the high/low gear change, and on the shaft that is directly under the motor). The spindle bearings were replaced a couple of years ago, and feel good, so we're assuming that that is not the problem. There seems to be too much play in between the gears, but we're not sure exactly how much is within tolerance. Below are two links to videos I took to try and show the noise that the machine is making. The quick changes in noise that you hear is when you adjust the spindle speed percentage up and down. Also, it makes a horrible grinding like noise when it first starts spinning. We've had the cover off and watched it start many times, and it is definitely not slipping. Not sure what the problem could be. Oh, and all of the bearings have been checked, and have the right amount of force on them to help with backlash. Thank you in advance for any help you can provide.





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[Ronniewhite70]

Hello, experiencing the same type of noise on our horizontal. I was wondering if you ever diagnosed the problem?

[donb9261]

Have the input shaft bearings been replaced and it could be the encoder. What control? I am an ex Toyoda service tech. Typically no more than a few thousandths on gear slop. Also could be the splines and keys for the gear shafts. Seen it before. But then it was the motor key.

[RCaffin]

An unexpected possibility is the power supply driving the spindle. If it has lots of ripple on it that can make a big noise inside the motor.

Cheers

[IMtech]

Have the input shaft bearings been replaced and it could be the encoder. What control? I am an ex Toyoda service tech. Typically no more than a few thousandths on gear slop. Also could be the splines and keys for the gear shafts. Seen it before. But then it was the motor key.

First off, sorry for the insanely late reply. I never got an email notification from this thread (that I saw), and honestly completely forgot about it. What exactly do you mean by control? Are you talking about the controller on the machine? If so, it's a FANUC 11M. If you grab the spindle and rotate it with your hand, there is enough slop to make fairly audible noise from the contact (moving spindle forward and reverse). Out of curiosity, we made a tool real quick that attached to a dewalt driver, and then put that in place of the motor. It still made the noise, even under what "should" be constant speed. We tried replacing the motor, as we had found one for a fairly good price, but it was to no avail. It definitely sounds, and looks like a mechanical problem. The most confusing part is that the gears look flawless, i.e. no pitting of any sort. If I remember correctly, we did replace the input shaft bearings, and the upper and lower thrust bearings on the high/low idler gear. Not sure how it's possible that there is gear slop in the absence of pitting, yet, it exists. Oh, and if it helps any, the problem did gradually increase, which is why we assumed it was the bearings. Any help would be greatly appreciated, as I'm at my wits end. I was wondering if it was possible to just remove the high/low idler gear, and have it hard chromed to add material to take out the slop. I'm going to do some last time tests this weekend to see if I can figure out the problem, otherwise, I may just tear apart the machine, and keep the parts for spares. I'd really hate to do that for such a simple problem though...

Thanks,
Braden

[IMtech]

An unexpected possibility is the power supply driving the spindle. If it has lots of ripple on it that can make a big noise inside the motor.

Cheers

The noise is there also when turning the spindle by hand, which doesn't happen on our other FV45, nor the horizontal. It almost sounds like improper gear mesh, but i don't know how that would be possible in the absence of pitting. The gears still have a nice ground finish, with the surface scratches in the direction perpendicular to the motion, thus making me think that the teeth can't be rubbing, or jumping. Also, with the steady increase in the problem over time, it seems to scream mechanical failure, but I'm not seeing where. If you have any ideas, I'd be extremely appreciative of any help you can provide.

Thanks,
Braden

[RCaffin]

The quick changes in noise that you hear is when you adjust the spindle speed percentage up and down. Also, it makes a horrible grinding like noise when it first starts spinning.

Obviously I do not KNOW, but the second sentence in particular sounds horribly like a bearing assembly not spinning properly. I get that sort of rattle on an old power drill of all things. The shaft rattles in the sleeve bearing for a moment when starting and stopping. Good power drill, so I put up with it.

I will assume you have looked at all the bearings to check them. OK. A possibility you have not mentioned is that a shaft is rattling INSIDE a bearing. That it, the bearing is (probably) OK, but is just slightly loose on the shaft. Or maybe the bearing is slightly loose in its housing. The former is more likely, and could make that sort of noise.

My 2c. Hard to tell at this distance.

cheers
Roger