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Mill: Tool release too powerful (sometimes)

Lupuscorp

Plastic
Joined
Mar 20, 2014
Location
California - merica
I run a couple of haas mills vf0 and mini mills. Every now and then when you release a tool it seems like it just stores up a ton of pressure and then releases. Making my tool eject like a rocket from the spindle, causing a hazard to myself tool tool holder part and machine!
How can I resolve this quickly or what am I doing wrong?
 
Buy a machine with a hydraulic drawbar. This is a symptom of the pneumatic cylinder Haas uses. Mine does it too.
 
I run a couple of haas mills vf0 and mini mills. Every now and then when you release a tool it seems like it just stores up a ton of pressure and then releases. Making my tool eject like a rocket from the spindle, causing a hazard to myself tool tool holder part and machine!
How can I resolve this quickly or what am I doing wrong?

If its mainly happening first thing in the day (or after the machine sits for a while) it may be the spindle taper heating and growing while running allowing the tool to seat deeper, and then shrinking up on the tool as it cools. If that's the issue the quick fix is to simply grab an empty tool at the end of your programs.

Dunno if this is a known issue with Haas. We don't have a one here and I haven't run one in years so I can't say "mine does it too".
 
This happens to us on our VF4. It also is evident during ATC changes, changing tools after heavy cuts have a pretty loud pop, and drill bits/reamers etc seem like they come right out.
 
We have 2 Haas VF2s and a Super Mini Mill, the mini mill is the worst one for the tool popping out hard. We clean the spindles all the time and grease the pull studs frequently as well and it makes no difference. It doesn't do it all the time but when it does it scares the crap out of you!
 
Yea it literally shoots it out with so much force I have to brace myself beforehand so I don't break my arm or bust my hand up.

Happens on my fadal too, although it sounds like yours is a little more intense than what I experience. Typically the first change of the day is the worst.
 
To set it all straight, it has to do with thermal expansion and contraction, then also with taper contamination.

The spindle gets warm during use, which causes thermal expansion and then you stick a cool/cold tool holder into the bore that is not expanded/enlarged by heat. The tool holder being cold/cool and slightly smaller, goes just the slightest distance further into the spindle bore. Any pressure during use, like drilling with a large size drill, will tend to push it even further up into the bore. If it is on a short cycle time and does not spend a lot of time in the spindle bore, it usually pops right back out, quietly. If it stays in for a while and swells because it also gets heated/warmed up, then it sticks a little, as it swells against the walls of the spindle bore. If it warms up a lot and the spindle bore is dirty and the tool taper is dirty, then it sticks a lot. Sometimes it will not even be released and you will get an alarm and have to deal with it.

Regular simple cleaning for the spindle bore and wiping down each tool as it is loaded will almost always stop the problem. While I agree that a little grease on the pull stud is a good thing, the spindle bore is the priority. Clean it regularly.

Air cylinders are used on the Haas machines and many others. It is a cost and maintenance reducing strategy. A hydraulic release would mean that a hydraulic system with pumps and high pressure lines would be required. This raises the cost of production and would require regular maintenance and higher initial costs for the machine.

From memory, I think that the size of the piston for the release is about 35 square inches and with the air to the machine at about 85 psi, that is about 3000 pounds of force on the tool release shaft. That is plenty of pressure, applied rather slowly so as not to bang or hammer on the end of the shaft, but at times it is not enough to overcome a poorly maintained spindle bore and tool. I'm too am guilty of not keeping things clean and get a tool that sticks once in a while.

Could I, as the great genius that I am, design a better release mechanism, you bet. But they have been using the same unit for over 20 years and I suppose they are reluctant to change now.

Oh well, I'll keep it clean and keep making money! :)

Mike
 
im really glad to see someone post about this short and sweet. the way you explain it is exactly like i get in my year old vf2ss. ive been working extremely hard to diag the problem and have my hfo helping me out. ive tried everything you can think of. ive read every thing i can find about sticking tools and even factory haas bulletins etc. i understand about thermal expansion and spindle warm ups and all the stuff that goes along with tools sticking. but its the tool popping out so hard that is this problem.

it has nothing to do with the tooll changer because it does it when manually removing a tool. its completely random. if you switch tool holders when you notice one tool in particular popping, it doesnt matter. same thing.

the only way i can get it to stop is by applying a very light coat of grease on the tool holder tapers. this stops it every time. just sucks that you have to have a mess of grease on your tools to keep it from making such loud violent pops.
 
That happens on my VF2's. The Haas guy said to grease the pull stud from time to time and also to not leave a tool in the spindle over night. We do that but it still pops sometimes.
 
Air cylinders are used on the Haas machines and many others. It is a cost and maintenance reducing strategy. A hydraulic release would mean that a hydraulic system with pumps and high pressure lines would be required. This raises the cost of production and would require regular maintenance and higher initial costs for the machine.

I have a Bridgeport GX1000 that uses an air over hydraulic tool release. There really is no maintenance except to make sure the cup of hydraulic oil is full. No noise, no pumps, no electricity, no lines other than air lines. So far so good.
 
I have a Bridgeport GX1000 that uses an air over hydraulic tool release. There really is no maintenance except to make sure the cup of hydraulic oil is full. No noise, no pumps, no electricity, no lines other than air lines. So far so good.

Air over hydraulic is also what I would do too probably. But, air/hydraulics and it has its limitations to, the biggest one being speed. All of the newer machines are going to super fast tool changes and that means that the system would have to be power down and power up. This would make it a little slower and speed is everything right now.

Straight hydraulics is much better, but like I said, adds cost and reliability issues. Life is a compromise unfortunately and it will always be.

Mike
 








 
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