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Insert Chipping

Ox

Diamond
Joined
Aug 27, 2002
Location
Northwest Ohio
Sorry about the pic. My camera doesn't doo small details well, but I think you can see enough to git the idear.

WNMG332 in a swiss - running 1018 and oil.
Tool is only facing and banging a chamfer on this job.

Insert corners chip out quickly.
I started with 331, but went to 332 to see if that might help, but no change.

I adjusted my tool C/L down .005 to see if I was too high, but that gave me a tit, so I put that back where I had it before.

Went from Iscar insert to a Kanna insert, and again - no change.


I have used this same tool for some time, and I have never noticed any issues like this previously.
From 1/4" 1018, to 3/4" 12L14, and it seems that I had some 1" in there at one point.
In most apps - it seems that this tool hasn't had to actually doo much turning, but mostly face and chamfer.

Now - in this app I doo have an interupted cut on the last pass as I am cleaning up and qualifying Z0 with a face-off after a hex broach, but that is just a clean-up pass at that anyhow.

I have also greatly slowed the RPM down as well.
If nothing else, that at least keeps the heat down once the insert has been chipped ....


I have ran this job on fixed heads with coolant, and not had this issue then...

I am almost through this run (should finish today) and I may or may not accept this job back again, at least in 1018 (we'll see) but just wondering if anyone has seen this before?


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I am Ox and I approve this post!
 

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Is it facing with no hole drilled?
You say the C/L is good, so the only logical answer is that the rpm's are too slow when it gets to 0 diameter.
Can you center drill or drill a hole in the part and then face it off?
 
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Yeah, well it's a bit more complicated than that...

I also face off after cut-off and use this tool as the "stop", and so that would git a bit hairy in that app...

I don't think that it is the "stop" app that is causing issues tho as this is the only job that I recall having this issue on, and it runs like that on other jobs as well. AND on the swiss, the bar does not fly up and hit the stop, it is already there, and the feeder just holds it tight while the spindle backs up and fetches a new bite.

I have fed out on fixed heads to a trigon/stop and hardly ever had a chipping issue in >1 million parts, so .... ???


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Think Snow Eh!
Ox
 
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Actually, you may have something there...
These are push-to-close collets.

But I've never had this issue 'till now, but I will keep that thought and see.
Actually, maybe I will program a pull back in Z before the X and see if that changes anything.
I can doo that quick/now...


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Think Snow Eh!
Ox
 
I've found that every time chuck (almost all of push) closes, load meter show some pressure applied to Z axis = to the stopping tool you use. I measured in between .001"-.006" depending on setup. I'd use something else to stop it, and I always pull back from the part before homing turret for tool change.
Hope this can help.
 
Just food for thought, I chased a similar problem on a facing process. Every part we did on that machine used the same material, tool and process to face and it worked fine every time. One part number in particular would chip the insert. It ended up being the thou or so the tip went past center was chipping the insert. Only time I ever saw it and only on that one part number
 
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Well, that would likely be caused by being below center, and the tit pulling on the insert, but will consider it.


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Think Snow Eh!
Ox
 
Well, the pull-back didn't change anything.


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I am Ox and I approve this post!
I always pull back before moving x this just in case. No reason not to.

When using a parting tool I noticed it was leaving a drag mark on some parts before I started retracting z.

Can you lower the barfeed pressure?
 
I never use those trigon inserts but I know my CNMG, DNMG, etc will chip super quick if I am facing off too much material on my Swiss machines…VBxx will break bad just facing off one part if taking much more than the TNR. Maybe check that out? Good luck!
 
My experience has been that excessive chipping was caused by too low an SFM in the cut.
A light feed but higher SFM might alleviate the issue.
 
I doo have my resolution set low. I don't have any need for 3mgb pics.

But the fine detail I don't think is anything to doo with that.
It's not like I'm pixeled out.
I am purty sure that it is just my auto-focus just doesn't hone in on where I want it to.


Also, I have DOC pretty low on the face cut.
Prolly in the .025 range....


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I am Ox and I approve this post!
 
I quit making parts out 1018 of 25 years ago because of bad material. I kept running into inclusions one stopped the spindle on my 42mm Traub screw machine. Several different sizes and from different suppliers. Told customers if they did not want to change to 12L14 I did not want the work.

Maybe 1018 is better today, I would not know.
 
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Well, the verdict is in.

I replaced the insert this morning, and performed a face-off and re-chuck (feed) and I could see evidence of chipping from just that partial cycle alone.

So - it seems that it is the push-to-close (apparently not really "dead length" after all?) collet chucking that is the culprit.
Just not sure why I am having so much issue with it on this run, and I haven't seen it prior?

May have to employ a secondary tool in the future.


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Think Snow Eh!
Ox
 
Well, the verdict is in.

I replaced the insert this morning, and performed a face-off and re-chuck (feed) and I could see evidence of chipping from just that partial cycle alone.

So - it seems that it is the push-to-close (apparently not really "dead length" after all?) collet chucking that is the culprit.
Just not sure why I am having so much issue with it on this run, and I haven't seen it prior?

May have to employ a secondary tool in the future.


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Think Snow Eh!
Ox
Lot of times if I have room in my turret i'll just cut apiece of 1.0 stock , face it and make a bump stop. Or i just move my facing tool down in x and set another offset for it.
 








 
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