Spindle Popping during tool change? HAAS

[AllenGauge]

We have a Haas VF2, When we do a tool change the spindle head pops (with or without tool in spindle). much louder then normal. Any ideas what the problem is?


It still runs fine, we just didn't want to damage the machine.

[Matt@RFR]

Allen, do a search. This has been covered MANY times.

[l u k e]

I have a VF2 which does the same thing on occasion. I have wondered if it is some sort of an air pressure problem. It seems to only happen if a tool is in the spindle for a length of time. If the machine has been setting, running at idle with a tool in the spindle it will pop when changed. Same thing happens if the air is not bled out of the system at the end of the day. I have seen a few different ideas on why they do this but my suspicion points to air pressure build up, I just have not gone threw a process to verify it myself.

[Machineit]

Although this has been covered before, it may be hard to find through a search.

What happens is that there is a broad flat air cylinder that pushes down on the shaft and compresses the washers to release the tools. The cylinder is quite large in surface area, in the neighborhood of 30+ square inches. Therefore it has a great deal of force, 85 psi times 30 equals about 2500 pounds of force on the shaft. But the stroke is only about one inch.

So the problem is that if you hit it with the 85psi all at once, it would slam down on the top of the shaft with quite a lot of force and very rapidly. To prevent this, Haas feeds air pressure to the opposite side of the cylinder that then needs to be forced out in order for the cylinder to move down. This reverse air causes the cylinder to slowly go down and hit the shaft gently, instead of slamming against it.

What you have is a failure of the secondary air supply. In other words, the air is not going to the bottom to cushion the blow. This is usually caused by the valve failing or the filter that lets the air in/out getting clogged up etc.

If you pull the cover off of the head you will see the lines and you can trace them to the valves. Trace them and clean the regulators etc. That will fix the problem.

It s quite noisy if it is not right and who knows, it could eventually cause other damage.

Good Luck----Mike

[dingo0722]

It’s a precharge failure. The prechage of air should be 4 psi, followed by the full blast. It could be the solenoid that is bad or the precharge pressure regulator which sit behind the spindle motor. If you have TSC you will most likely get precharge failure alarms. If you don’t have TSC, you won’t get an alarm and the only symptom will be the hard pop during tool changes