Problem- Funky wear pattern on CAT 40 holder?

[peter.blais]

Hi guys...

I think one of my guys may have gotten a chip on a tool holder when loading, or it just landed there in the tool carosel. I was about to change this end mill, and found this funky wear pattern on the collet body:



The same wear pattern appears on my spindle now. I checked the next tool, a little chamfer, and it has the same marks, only much lighter. It almost is like some plating got transfered from the tool holder to the spindle, and then on to the next holders.

Any advise? Should I toss this holder? Attempt to clean the spindle?

[HuFlungDung]

You could carefully check the spindle taper for any burrs and nicks.....anything that can be detected by a fingernail is enough to create a gap in which the tool shank can vibrate. What you see is fretting corrosion, and is typically brought on by heavy cutting.

You could also check the drawbar tension, because in heavy cutting, the tool may be on the verge of pulling the tool out of the taper enough to permit it to 'bang' microscopically and this will result in the corrosion that you see.

Now I really do not know if it is possible to avoid this 100%, because I've seen it happen on every machine I've ever run, even the older mills with a threaded drawbar (which will never permit any slack) when performing heavy cutting.

I usually just polish the shank if it bugs me too much. Also, apply a little oil to the shank, rather than run it bone dry, because lubrication is bound to help reduce the amount of corrosion.

If you have a taper guage, you could also blue it up and check the overall contact of the taper.

[peter.blais]

Ya, I think it may have been caused by some chatter we were having earlier. I blued up a tool holder that was in new condition and stuck that in there, it looks even top to bottom.

I just felt all around in the spindle, and can't feel anything. The matching marks in the spindle you can't feel with a finger nail, but the ones on this particular tool holder, you can.

I heard a little bit of lithium grease type spray (very light coat) helps, not only for this but to make the tool changes a little smoother as well. I'll probably start doing something like that and also just make sure things are chatter free- the trouble program is fixed now anyways, so who knows how long that tool holder has been looking like that.

I just thought it was real odd that it's only 150 degrees or so around the holder- i thought it may have been the result of a holder slightly cocked in the bore, putting a lot of load on that one area.

[Geof]

Originally Posted by peter.blais .....I just thought it was real odd that it's only 150 degrees or so around the holder- i thought it may have been the result of a holder slightly cocked in the bore, putting a lot of load on that one area.

Maybe the uneven wear occurs because the chatter frequency is harmonically related to the spindle rpm so the taper bangs harder against one side. Alternatively if the tool had a bit or runout maybe this could create assymetrical wear.

[dertsap]

that would have to be some extreme chatter to damage a cat 40 taper .
considering the wear is fairly even around the tool then it looks to me that a pull stud has been loose at some point and damaged the spindle taper , or a chip got in the taper and the tool was rocking on it while cutting

[peter.blais]

Well, the good news is that the machine is almost new and has very few hours- I've owned it since new and never had a tool loose in the taper. Other then this new mark at the bottom, and a few little specs here and there, the grind marks still look prestine.

We have used it mostly for light prototyping use, until recently.

I think it may hvae been just a chip that got in there and caused the holder to rock over onto that edge, loading it up right along there. I can't find any evidence though of the actual chip, but who knows it may have fallen out many tool changes before I went to change the tool and noticed it.

That tool was a z carb endmill and it didn't last all that well either- may have had some runout.

The other thing that was odd, but I didn't think anything of it until now- it wasn't making any good POP's when changing tools after roughing. Usually it makes a pretty healthy pop. Perhaps if the tool wasn't sitting in there 100% due to some foreign object, that'd stop it from getting so worked into the taper.

The program which ran a bunch right before I discovered this was pretty pedestrian I think, 41 IPM / 3950 rpm / .1667" DOC, slotting A36 with a Z carb. I don't think that's really "hard roughing" and it sounded real happy. I'd say I was in no rush.

I guess I'm just going to clean the heck out of the spindle, lube things up a bit and let it ride.

What do you guys do in terms of maintence in this regard? I let my tool changer do a half change and then e-stopped it. It looks decent, but there are a few face mill curlies and stuff in there. Anybody cleaning this stuff out? How about the actual spindle taper? I'm real leary of bringing anything abrasive to bear on it. To date I've just rubbed real hard with a few fingers and a lint free cloth.

Thanks guys!

[dertsap]

Originally Posted by peter.blais ? I'm real leary of bringing anything abrasive to bear on it. To date I've just rubbed real hard with a few fingers and a lint free cloth. Thanks guys!

fingers work the best , most stuff will stick to your fingers and you'll feel anything odd , i don't like the use of rags because they can easily leave a chip behind

[haastec]

The loud POP is the spindle and tool tapers sticking together due to the buildup you are experiencing. This will only get worse if not thoroughly cleaned and will cause t/c problems down the road.

I often recommend cleaning both the spindle and tool tapers with WD-40, or similar, and gentle cleaning with scotch brite pad. In my shop I have completely banned the use of any type of grease, including lithium, on the tapers. I have found this solution to be a very short term fix and the problems usually return worse than before. Grease = dirt/chip magnet.

The best solution for me has been diligent attention to the tapers. This means anytime a tool is removed or placed in the spindle it is cleaned with WD-40 and a rag. If needed I will also use gentle pressure with a scotch brite pad to cut through the grime.

There are many sucessful opinions on how to care for the tool tapers, mine included, so do what you feel is best for your machines.

Also, double check to make sure the pull studs are not to tight as this can cause distortion in the taper.

Hope this helps.

[peter.blais]

So,

I cleaned all those holders this morning, and moved that end mill into a fresh collet body with an undamaged taper. I also rubbed the hell out of the inside of the spindle bore, first with a WD-40 soaked rag, and then with a finger. I can't feel anything.

I just ran the machine for 2-3 cycles, and I have the exact same damage again- same spot, looks pretty much identical.

I guess i'm going to need to get a light up in there and try to see, I'm thinking I will go pick up some soft scotch brite pads and try to clean it out.

Isn't it funny how you can have an old beat up machine for years, that you don't care about- and never have anything happen... Then you get a new one, and sure enough...

[mactec54]

peter.blais

You get this from buying the cheap tool holders, the tapers are not matched to the machine taper so the tool moves around at the contact point causing what you are getting, I find most marti tooling does this & other cheap tool holders

You will aso find that if you torque the pull stud to the correct number of 85ft pounds the top of these holders swell the taper at the top this then won't let the tool go all the way up in the spindle, You then get the same problem as well,as a bad fitting taper on the tool holder

[peter.blais]

Hmmm- That may be, but in this case I think it was a chip / debris.

I buffed things up lightly with a little bit of wd-40 on a scotch-brite pad. The pad came out with one tiny chip, smashed- and some goopy / dirty stuff. The spindle looks as new again- I was definitely careful not to apply much pressure and do anything that would change the taper grinding beyond usual wear & tear.

I grabbed yet another collet body, reloaded a fresh tool, and ran the program. After a few times through, I still don't have any funky wear, and my tool life is about double so far.

Fwiw, the marks on the old collet body rubbed off also with a very light scrubbing. I put a finishing end mill in there, and they have not returned. I'm thinking I can return those holders to service as well.

That wasn't really a very thrilling experience but all seems well now. I am going to go through though and check the torque on my retention knobs as some of you have suggested, my spindle does always release with a bit of effort it seems. It is definitely partially just thermal expansion.

I'm a relieved and happy camper now though, thanks to everybody who helped.

[Pondo]

Originally Posted by mactec54 peter.blais You get this from buying the cheap tool holders, the tapers are not matched to the machine taper so the tool moves around at the contact point causing what you are getting, I find most marti tooling does this & other cheap tool holders You will aso find that if you torque the pull stud to the correct number of 85ft pounds the top of these holders swell the taper at the top this then won't let the tool go all the way up in the spindle, You then get the same problem as well,as a bad fitting taper on the tool holder

We had a Haimer rep come in and show the machinists how to properly use their shrink fit tooling and demonstrate HSK tooling for our Stinger 5-axis. It was a measurable difference in the standard 40 taper holders when he torqued the pull stud down to demonstrate this exact problem. He could tell by the wear patterns on the holders if the pull stud was torqued down or not. We do the pull studs hand tight and use a drop of loctite now to avoid it. Sucks if it ever needs to be removed, but avoids the problem.