Haas vf2ss taper locking

So over the past week my 20015 haas vf2ss has started to develop some taper locking issues. Essentially a moderately loud thunk (non metallic - making me believe its taper lock and not drawbar related) upon tool release. It hasnt gotten to the point of a failed tool change but i fear it will get there eventually. A little info - Its cat40 (i dont even think they offer a vf2 with any other size) and it only happens with ONE tool. Its a harvey 3/16 downcut endmill designed for plastics. Im roughing in plastic with a high speed toolpath that runs for about 25min. The same tool runs for about 2 min later in the program and does NOT have any problems with tool release during that time.

I have tried every holder i can fit that tool into hoping it was just a bad holder. All my holders are maritool, ordered from maritool. So they are quality. That did not change a thing. So i decided to check taper engagement and i am well within 80% engagement. I keep my spindle and tool tapers very clean and never leave a tool in the spindle over night or weekends. I have tried the "grease the top inch of the tool holder and pullstud" and that changed that nothing. The spindle casting never gets even remotely warm to the touch so the tool holder shrinking in doesnt seem to be the case. We purchased this machine with 14000 hours on it about 3 months ago and it went through a whole inspection by haas techs. The spindle taper, along with everything else, was deemed well within factory specs. The drawbar pull force was right around the 1700lb mark. I spoke with a haas service tech and he had less input than my google searches, i did however find out that this year of vf2ss does not use a precharge on the drawbar during a tool change so that has been ruled out as well.

The only things that i can think that are causing this would be the fact that its a downcut endmill causing all the cutting force to go towards the spindle instead of away from it. Or the fact that my shop is based in az and the past week was the first week of consecutive 100+ degree days. My shop is swamp cooled and never gets above 80 degrees inside. I do make sure to leave a light film of oil on anything i dont want rusting every evening even though it does not seem to get humid at all in the shop.

If anyone has any insight on what could be causing it or any advice on things to try it would be greatly appreciated. I was less than impressed with the service tech i talked to, and would really rather not have him try and diagnose this. Let alone even touch my machine.

It's probably time at max speed causing the sticking, not the endmill. Too small, cutting plastic - it's not going to exert much force on the spindle one way or another.

Let us know the cut time and RPM of this and other tools.

Most tools run at 12000 rpm unless im finishing. The tool that is causing this issue is running at 12k for just about 16 min(this is the tool path that is having taper lock issues). It does run again for 12 min but at 900rpm(no taper lock issues). I have another tool that runs for 20 min at 12k with no taper locking issues.

Overall cycle time is 1hr 38min and this program runs day in and day out 5 days a week.

In a previous version of this program I was using a different 3/16 endmill for roughing that ran for 40min at 12k with no taper lock issues. That was a standard upcut endmill.

And yea i agree, i dont see any way any form of significant force would be generated by a small endmill in plastic. I just couldnt think of anything else at this point

Centrifugal force expanding the spindle at high speed causing the holder to get pulled deeper into the spindle than draw bar force alone. This being a small machine there may not be enough metal in the spindle to prevent this happening. This is why HSK spindles are considered better for high speed. The spindle nose expands into the tool holder increasing grip as speed goes up.

I have discovered that dry tapers are not good, at least on a Fadal. I used to put a little clean soluble oil coolant on the tapers after cleaning them, it worked just as well as many other things like a little light grease or way oil, to help the tapers release on tool changes.

Does the pull stud have ugly dings on it?

12k for 16 min- im almomst certain that if you pull the tool holder out of the spindle- you will feel a considerable heat differance than before it ran. I cant say for certain-but I had the same concern when I ran haas machine tools and always presumed it was thermal expansion on the holders behalf.

Nerdlinger said:

Does the pull stud have ugly dings on it?

Click to expand...

They all look good as new except for dimpling on the underside of the angle where the gripper balls bite in a little. I have tried multiple brand new pullstuds when it first started happening. It did not affect it at all.

allloutmx said:

12k for 16 min- im almomst certain that if you pull the tool holder out of the spindle- you will feel a considerable heat differance than before it ran. I cant say for certain-but I had the same concern when I ran haas machine tools and always presumed it was thermal expansion on the holders behalf.

Click to expand...

I actually have yet to check the tool holder itself right after it finishes running that tool. I have however checked the spindle casting temp with my hand right after that tool finishes and its cool to the touch. Granted the casting i believe is coolant cooled while the bearings are air/oil cooled and lubricated so maybe the spindle taper is getting warm even though the coolant is keeping the spindle casting cool? But why then would the other tool that runs even longer at 12k not pose any issues i wonder.

Deylan said:

I actually have yet to check the tool holder itself right after it finishes running that tool. I have however checked the spindle casting temp with my hand right after that tool finishes and its cool to the touch. Granted the casting i believe is coolant cooled while the bearings are air/oil cooled and lubricated so maybe the spindle taper is getting warm even though the coolant is keeping the spindle casting cool? But why then would the other tool that runs even longer at 12k not pose any issues i wonder.

Click to expand...

right- the spindle is "cooled" but the tool is not. the tool holder will experience more thermal growth or faster thermal growth then your cooled spindle and in doing so the tool holder grows inside of the spindle taper.

Deylan said:

...But why then would the other tool that runs even longer at 12k not pose any issues i wonder.

Click to expand...

Which tool runs first?

Do you do a warm up before you run the first part?

Does it happen throughout the day, or first thing in the morning?

I'm wondering if the tool that is giving problems is starting with a cold spindle, and that tool does the warm up. The next tools load into an already warm spindle, etc.

guest said:

Which tool runs first?

Do you do a warm up before you run the first part?

Does it happen throughout the day, or first thing in the morning?

I'm wondering if the tool that is giving problems is starting with a cold spindle, and that tool does the warm up. The next tools load into an already warm spindle, etc.

Click to expand...

yeah Im with this guy too- having just read the part where you have multiple tools running 12k for longer durations etc.

guest said:

Which tool runs first?

Do you do a warm up before you run the first part?

Does it happen throughout the day, or first thing in the morning?

I'm wondering if the tool that is giving problems is starting with a cold spindle, and that tool does the warm up. The next tools load into an already warm spindle, etc.

Click to expand...

I do a spindle and table warmup every morning for 20 minutes. Probably a bit excessive but it gives peace of mind. Time of day/first run/last run doesnt seem to have an effect. Just now another tool started doing it as well. Its starting to look like my spindle may need a regrind and the first tool that started doing it was just the first sign. Anyone know of any reputable spindle grinders in the phoenix, AZ area?

Well the good news is you can rule out the end mill.

You need to oil the taper...put some way oil on your finger and coat the inside of the spindle. Technically you should do this every day but once a week is usually good enough. In your case I would do it every day for a month then see how long it takes for a slight thump to occur, then you know it's time to redo it. Basically a daily used machine should have it done every Monday, as well as some grease on a pull stud and on the movable "fingers" on the took change arm.

Pro tip: if you have a probing system and this is occuring there is a chance that it can knock the probe out of calibration. The harder the bang the more chance it will happen.

As was mentioned, a bit of grease on the spindle contact surfaces can give you temporary relief (As seen on TV!) for spindle sticking. Next time you can do a little service on the mill, clean the spindle taper thoroughly, then go through the rest of the tools and clean their tapers too. Then clean the spindle again, see if it's picked up anything after cycling the holders through.

Now, take a little bit of clean grease, and put a very light coat on the sticking holder's taper. Pop in into and out of the spindle taper a few times, look at how the grease is now distributed on the toolholder taper. If you gave it a uniform coating, but now you see "bare" areas, there may be a deformity of that taper that isn't obvious.

In any case, clean off excess grease, but not in the taper area. Put a little more grease on the pull stud itself (so that it'll get into the drawbar socket), then run that tool through the warmup cycle. During the next part run, see if it now releases OK.

Let us know what you get for results.

Milland said:

As was mentioned, a bit of grease on the spindle contact surfaces can give you temporary relief (As seen on TV!) for spindle sticking. Next time you can do a little service on the mill, clean the spindle taper thoroughly, then go through the rest of the tools and clean their tapers too. Then clean the spindle again, see if it's picked up anything after cycling the holders through.

Now, take a little bit of clean grease, and put a very light coat on the sticking holder's taper. Pop in into and out of the spindle taper a few times, look at how the grease is now distributed on the toolholder taper. If you gave it a uniform coating, but now you see "bare" areas, there may be a deformity of that taper that isn't obvious.

In any case, clean off excess grease, but not in the taper area. Put a little more grease on the pull stud itself (so that it'll get into the drawbar socket), then run that tool through the warmup cycle. During the next part run, see if it now releases OK.

Let us know what you get for results.

Click to expand...

Grease works on the taper but it's a magnet for debris, vactra 2 is much cleaner and easier.

I think oil will do the same. It's why I suggested cleaning ALL the toolholders too, as dried coolant residue can also hold chips and debris, so cleaning all surfaces should be done every so often. In fact, so should the carousel pockets too, but that's usually a PITB and isn't done. Newer side mount carousels do a better job of isolating open pockets than older machines, but can still pick up crap over time.

Not the taper. You swamp cool your shop but do you dry your air?

I would take a felt marker and completely color the taper of the bad toolholder. Perhaps also color the taper of another holder that doesn't give problems. Run the program a few times and then observe the remaining coloration on the tapers after a few tool changes have occurred at operating temp. Maybe you'll see something, like a bulged out shank from an overtightened pull stud.

Vibration of the tool will help seat the taper further, too, which might lead to the overtightness on release.