Replacing Y axis Ballscrew/thrust bearings.

[steedspeed]

Hi

I have a VF2 and the Y axis is noisy.

Has anyone here done this fix?

Any idea what the HFOs charge?

Not sure if I should have a go myself and what complications I might encounter.

Any advise would be appreciated.

[Geof]

I have a VF0 with a noisy X axis and it has been nosiy for about 4 years, maybe longer. Periodically we check the backlash and interpolate a few test holes to make sure it is still performing within spec and just ignore the noise.

I do have to admit I went into the parameters and cut the maximum speed on the X axis down by half because it made so much noise it was frightening.

My advice is so long as the machine is cutting fine just ignore the noise.

[crabbass]

check the simple things first. remove the way covers to see if it is something else inside. I don't think you should ignore a sound even if everything is within tolerance. If the noise is generated by friction between the guide rails, or rotating components (servo, ballscrew, nut, thrust bearings) It will most sertainly degrade the machines accuracy, If the noise is caused by some chips being dragged around by the covers, or somthing dragging along the frame of the machine-Remove it, Straighten it, etc.
If the screw, servo, nut, or bearings are actually the cause, don't just replace them, try to determine why they failed, (lack of lubrication, foreign object contamination, etc.)
Correct the root cause before you change anything! If you are sure it was normal wear and tear, replace and move on. Keep in mind greater than 80% of bearing failures are caused by contamination before and during installation.

[steedspeed]

The sound is louder in one direction than the other which leads me to believe it is probably the thrust bearing. Y axis works pretty hard with 710 ipm rapids on such a small screw.

Does anyone know the part number for the thrust bearing? I don't want to buy it from Haas as they charge 3 x the price a bearing shop would.

[Haas__man]

Hey, I agree mostly with Crabbass, Ignoring the noise would be a bad move. I would suggest periodically looking under waycovers and cleaning whether there are noises or not and check for good lubrication etc. Also check that all wipers and waycover seals are working properly. Pay special attention to the Left hand X axis waycover. The X axis motor is directly underneith and if it gets wet could be very costly. Also coolant on your ballscrew is not good for ballscrew.
As for the noise this is a good way to check what your problem is:
Listen to the noise that it makes as it's moving. If the noise has a constant pitch then the problem is either with your bearing pack which is located at your motor end of the ballscrew, or your support bearing which is at the other end. If the noise changes in pitch as the axis moves back and forth then it is very likely that the problemis with the nut on your ballscrew. As far as I am aware you cannot replace the nut on its own, however there are many places that recondition ballscrews. It is also worth checking out the prices of ballscrews at your local HFO because depending on the age of your machine you could find that is cheaper to buy a new one than to have one repaired! (strange but true).
Hope this helps.

[Geof]

I should have put in more detail in my post.

We did strip off all the covers and called in the Haas technician. Using a stethoscope we determined it was probably the ballnut but it is a bit difficult to be definite because the sound also transmits to the thrust bearing; it just seemed louder on the nut. The first supposition was inadequate lubrication so we disconnected all the lube lines and proved that they were flowing. Then I rigged up a lubricator using a grease gun and some tube and pumped way lube into both the bearing and nut until it was running out past the seals; the noise did not change.

So we put everything back together, checked that there was no backlash and that the machine could interpolate holes like always, reduced the rapids on that axis; then ignored it.

But we don't exactly ignore it we do check backlash every six months or so.

The quote for replacing the ballscrew and bearing assembly was around $5000 and a couple of days time; I figured I would simply delay spending this kind of money for as long as possible.

[mls]

Here is the prices listed on the Haas website of there prices on some of they repairs it says $1295 for the y axis screw installed with the screw it does not say anything about the thrust bearings. If they told you $5000 plus time this would be like stealing and lying.
Hope this helps Mike


FAIR SPARES - THE HAAS WAY

Fair Spares - The Haas Way
Our Honest Service Value policy means reasonably priced replacement parts and labor charges across the entire network. Take a look at the examples below. We believe in transparency and honesty in pricing. Haas service charges are set fairly – exactly the way we’d like to be treated by our suppliers. Compare these examples with any other machine tool company, and you’ll see why Haas is the best value for CNC technology available today.

Part Name Part Number Installed Price
Axis Amplifier 93-5550C $795.
Spindle 93-30-0319A $3,295.
Gearbox 93-30-9994 $2,995.
Ballscrew, Y Axis 24-0023 $1,295.
Keypad 61-0201 $495.
LCD Screen 93-1129A $1,195.
Vector Drive 93-69-1000 $1,995.
Processor 93-1010F $2,495.
Coolant Pump 93-30-0125 $795.