[gangpw924]

1. Machine was purchased June, 2012, just pass the one year warranty. This is a six months problem that I had with this 2012 Haas VF-1
2. For the past six months, Haas Tech has show up 4 times, replaced the Z axis top mount and bottom bearing twice, change some parameter setting, problem seems to go away whenever they done the service with it. It is an intermittent problem, tough to trouble shoot.
3. Z axis Way cover has been cleaned and check it out good.
4. Haas Tech inspected the Ball Screw Assembly and linear guide looks clean, grease lube is plenty
5. Machines still cutting part with excellent result, it all looks normal until you get this screeching noises now and then.
6. As Aug 15, 2013, the screeching noise become more constant, (see the atached video)
7, Next move is replace the Servo Motor, see if help in anyway.

If anyone had experienced similar issue, need your input, Thank You

[haastec]

Do you know what the tech checked in regards to the ball screw? How many times has the thrust bearing (motor end) been replaced?

The sound you are hearing is normally due to a bad thrust bearing, but it is possibly only a symptom of what the real problem possibly is. If the ball screw is not parallel to the z-axis, that will definitely cause the thrust bearing to go out first but it will eventually cause the ball screw to fail.

I would request that Haas replace both bearings, thrust and support, along with the Z-Axis ball screw. Have them verify that the new ball screw is straight.

I ran into this exact scenario a few years back. Thrust bearing was replaced several times lasting only about 7-9 months and the ball screw was replaced once. I came in and found that the ball screw was not straight. Replaced the thrust bearing along with a new ball screw. Verified alignment and the machine ran many years without issue until it was sold for newer equipment.

Since Haas has been working on this wile under warranty, I am assuming that this is still a warranty call, correct?. If so, keep your paperwork and ask for copies of the service reports. Once a fix is in place, I would not call it fixed for an additional year. If it fails in that time, even if out of warranty, Haas has a very good reputation for fixing issues after the warranty period has expired.

Good luck and be sure to post updates to your progress.

[CaboWaboKJB]

Just a shot in the dark, but it sounds like it only does it on when moving in Z minus. Could it be a counterweight issue ? Maybe not the correct hydraulic pressure in one or both of the cylinders. If a cylinder leaks it could take months for it to leak enough to show any symptoms.
Or, try re-leveling the machine. Sometimes you can end up with a machine that is "level" at the table, but there is some twist in the casting. Although, I would think the service tech would have checked for both of those possibilities.

[haastec]

Aparently the original poster no longer needed the help of the Forum.