Ball Screws

[fab3]

I run a 20 year old Mazak with flying optics, I recently noticed multiple ridges on a circle I cut. The ridges were on both sides of the Y axis on a 5 inch circle cutting at 175 inches per minute. The weird thing is it can cut a much smaller circle at that speed with no visible ridges. I keep the ball screws and guides as well kept as possible. I would like to know if there is any type of maintenance that can be done to solve this problem or at least prevent problems down the road. Or is this a pending problem on all older machines with flying optics

 

[MikeHalloran]

That sounds like a mechanical resonance.
If nothing is loose or rattling, try a slightly different cutting speed.



Mike Halloran
Pembroke Pines, FL, USA

 

[LASERNINJA]

The machines I work on are from a different manufacture. But, in my experience, I've tried to cut small holes at high feed rates and the machine never achieves the target feed rate through the operation.

It may be possible that on geometry smaller than 5" the machine is not reaching the 175ipm and the inertia of the axis isn't high enough to cause the mechanical back lash to be visible. If you cut the same hole at slower feed rates and the problem goes away, you have backlash.

And this is the part I'm not sure about. I heard once that Mazak uses a pre-load screw, bolt, spring or something on their ball nuts. That would make it possible to correct for the backlash.