Cat 40 tools sticking and banging when released. What to do? Too much knockout dist?

Hi Guys I have a Fadal 4020 here and lately ive been getting some more serious problems with tools sticking. It will release on its own, but when it does sometimes there is a crazy bang when it lets go. I know some of this is normal, but this seems a little extreme. Its so bad sometimes that it has actually tripped the E-stop switch built into the toolchanger to protect the whole toolchanger from a crash up and down.

Ive done a lot of reading on this, its been covered over and over I know. Tried cleaning taper and all tools without much help. Tried very light skim of antiseize, tried little way oil. The oil seems to be about the best but I only get about an hour or less before it starts again. Any other magic treatment I can try? Heard light skim of moly grease but not sure I want that mess. Do I need to scuff tapers to hold oil or something?

I recently installed a lightning cool through coolant system on this machine (maybe spring/summer) and I noticed the knockout distance is much higher. Its at 0.100" right now. This should be much less right? What is a reasonable number? 0.030-0.040"? Could this be causing my violent tool ejections? If it was smaller it has less time to accelerate the tool im thinking. Any thoughts or suggestions?

I use some teflon spray, which I buy in a gun store, on the spindle taper and some WD-40 on the tool changer arm. Works well for me.

This sounds exactly like a problem we had back in the late 80's. We had just purchased a Fadal 4020 and within a week, tools were sticking, load bangs, faulting the machine out. After dozens of visits by the techs, we tried "puffing" teflon powder into the taper, oil, you name it, they even changed out the whole spindle unit, still nothing worked. After 3-4 months of a machine that was basically a manual tool change machine, I was talking to lawyers about forcing Fadal to take the machine back and get all my money back, my operator was going over the parts list and diagrams and found a bracket that held the limit switch on the tool carousel was installed with the washers in the wrong side of the bracket. As the tool change was happening, even the slightest up/down pressure on the tool carousel would trip the switch, make the whole machine pop like the tool holder was stuck in the spindle. We changed the washer location and the problems with the spindle went away.

No idea if any of that relates to your problems, but might be worth looking at.

Hey, at least it is releasing the tool! The one I worked on wouldn't after a good use of a roughing tool. It would sit there with the holder in the carousel puffing and puffing, until you would give the tool holder a good whack with the soft hammer. Our solution to the normal sticking tools was to keep the tapers and spindle clean, like every day or two and dip the tapers in clean coolant. I tried all kinds of things on the tapers but clean soluble oil coolant worked as well as anything. I also ran the air at 110 psi to give the tool release a little more oomph, which did help.

The knockout distance normally has a fairly tight tolerance, you don't want to go guessing it. Find out what it is supposed to be and set it correctly. On my mills, NOT Fadals, it is around .02" +/-.0025"ish. I don't remember it all exactly off hand.

Isn't there a common complaint with either Fadals or Haas' about a filter on the tool change system that looks like an aquarium bubbler stone that clogs up and causes loud/sticky tool changes? I feel like I've read several threads about that here.

I called Craig at lighning cool and there is an adjustment for the knockout length. I attempted to adjust this but ran out of thread. Had to machine a spacer to get me back in the thread range but have it adjusted properly now. Knockout distance is about 0.035 - 0.040" now and seems to be a huge improvement so far!

Craig also told me there is a high flow air line kit you can get for the drawbar as well. Right now it uses a 1/4" line and the piston slowly moves down to eject tool, then takes split second for pressure to rise high enough to break it free. The new kit uses 1/2" lines and idea is that the piston moves down fast enough to create an impact to help remove tool instead of force from air pressure alone. Supposed to give smoother more reliable tool release. Seems like good idea. Might try that if I have more trouble down the road.

I ran the machine all last night and today and toolchanges are great now. So much smoother now since reducing that knockout length. Im really surprised it made as much difference as it did. Maybe the drawbar piston was crashing into the end of cylinder or something. In any case its way better now then it was.

Your air piston for the drawbar could be cracked. Fadal used a square aluminum piston, with the through hole being counterbored on one side, and this is the weak spot.

When cracked, air leaks won't allow the piston to build enough pressure to fully and timely release the tool clamp mechanism.

You gotta dive into the head a bit to check the piston...

Once we changed the cracked piston, our tool change problems went away.

ToolCat

Yes I did have that problem this summer actually. Thats why I finally bit the bullet and bought the lightning cool setup. Needed a new piston anyway and always wanted through coolant so decided this was good time to upgrade.

Machine ran perfect the rest of last week after adjusting it. Still cant believe it made as much difference as it did. Get lucky sometimes i guess.

cnctoolcat said:

Your air piston for the drawbar could be cracked. Fadal used a square aluminum piston, with the through hole being counterbored on one side, and this is the weak spot.

When cracked, air leaks won't allow the piston to build enough pressure to fully and timely release the tool clamp mechanism.

You gotta dive into the head a bit to check the piston...

Once we changed the cracked piston, our tool change problems went away.

ToolCat

Click to expand...

Ditto. Same thing happened to mine. Drawbar could also need replaced. Fairly easy repair... But not sure how it is with the through coolant.