2000 VF_0 Alarm

[horst007]

Hey everybody could use a little help in diagnosing a problem I have been having with a 2000 vf0. The little bugger will run fine for weeks and then all the sudden I get Alarm message 291 Low air volume/pressure during ATC. When I start getting this alarm it comes in bunches and then it will stop and wont happen again for weeks. Where do I start to try and track down the problem. We have 6 other mills 5 of them Haas and they never give a lick of trouble with the tool changes just this vf0. Please help?!!

[Haas__man]

Is Diameter of air line to machine the same size as your other machines?
Where is the VF0 in relation to your compressor? Is it the last in line of all machines for example?
During a tool change does air pressure drop below 80 psi?

If air pressure and volume is good then your problem could be with the solonoid that unclamps the tool.
Remove head covers.
Look where the main cable carrier bolts to the head. You will see that it is attatched to a bracket with lots of plugs and sockets.
You are looking for a six or eight pin plug (can't remember which)
It is the power to solonoids.
Check that all wires are secure and not loose, you should probably turn off machine while doing this so you don't get a shock if you find one that is loose. Pay close attention to the red wire.

If the wire is loose, what can happen is as the head moves upward during tool change, the tool release piston repeatedly fires and therefore uses more air - hence the alarm.

Hope this helps

[horst007]

Yes sounds like you are on the right track there haas man. I just want to be sure I am on the right track before tearing into it when I have the chance. It does on occasion sound like the solenoid opens and closes really fast when the head moves up and down during tool changes and we just had a wire replaced that goes to the thermal sensor on the spindle also. Thanks a lot I really appriciate the help.

[Brendan]

I had the same problem on a 2000 VFO
Ended up being the air pressure drop after the air dryer on the compressor would work hard for along time it would begin to freeze reducing air flow to the machine.
You could go back and check the pressure witht the machine running but during a change it would drop low enough to kick the alarm.