Finish Issue - Grooving Tool - Mazak Lathe - 6061-T6

holows88 · May 7, 2015

Hello all,

I'm still relatively new to programming on our Mazak QT lathes w/Mazatrol.

I'm hoping someone can give me some sort of recommendation on how to improve the surface finish on a groove in a part we're making. Here's what it's programmed to currently:

Cut-Off/Grooving tool: SGIH 26-3 with GTN3 IC328 insert (.123 wide)
Feed: .0005
DOC: .01
RV/FV: 788 (Default for aluminum on our controller)

I broke a blade using these settings, so I'm very wary of being too aggressive:

Feed: .0080
DOC: .01
RV/FV: 788

The cut is giving me a very raggedy edge. The blade is straight, the height is dead nuts. Does anyone have any advice?

Thanks in advance!

Philabuster · May 7, 2015

Feed .002" to .004"
DOC = chip peck. Make this number bigger than your total groove depth and it will not peck. Change it to 1.0 for example.
RV/FV = SFM of roughing and finish tool. Change it to 1500 to 2000.

Run the shit out of it.

holows88 · May 7, 2015

Thanks Philabuster, I'll give it a shot and see how it goes.

Fortunately, I had a backup blade, so I'll get it running today. :-D

fpworks · May 7, 2015

You increased your feed by a factor of 16? lol

26mm tall blade that is .123" wide...hmmm...I hope you don't have too much projection on that...

holows88 · May 7, 2015

Update: The insert keeps flinging out of the holder (which could be why it was in the drawer). Will try again with the new holder tomorrow.

holows88 · May 7, 2015

Cutting a 6" round bar down to 3.8"," 1.3" projection out of the holder. Good news is the blade didn't snap, but not holding inserts is problematic.

Right now I'm roughing it down with my slow (.0005"/.01") feed, just to avoid stressing the bar, then coming back with a finishing cut at .002"/1.0". Hoping I'll be able to repeat the results, as it's a critical dimension for our customer.

Philabuster · May 7, 2015

holows88 said:
Right now I'm roughing it down with my slow (.0005"/.01") feed, just to avoid stressing the bar, then coming back with a finishing cut at .002"/1.0".

The .010" peck is NOT doing you any favors. The chips end up getting caught under the tool and it makes the finish look like shit as the tool is entering and withdrawing from the cut every time the insert removes .010" radially (.020" from the diameter) from the groove.

litlerob1 · May 7, 2015

I agree with Phil, pecking a groove is gay unless it's like a 1" peck. It causes the blade to deflect from side to side also. Also grooving with a part off tool is gay. But if you are only out 1.3" and getting a new holder----get a proper grooving tool not a part off tool, use them shits for what they are parting OFF.

Robert my ±2

Gobo · May 7, 2015

Please tell us you are using coolant.

EM112358 · May 7, 2015

litlerob1 said:
I agree with Phil, pecking a groove is gay unless it's like a 1" peck. It causes the blade to deflect from side to side also. Also grooving with a part off tool is gay. But if you are only out 1.3" and getting a new holder----get a proper grooving tool not a part off tool, use them shits for what they are parting OFF.

Robert my ±2

Aren't we all just a little gay?

Just for reference. We cut off in aluminum on a 4" machine with no peck at something like 700sfm at 0.009/rev. There's no reason you can't do the same or close to the same for roughing. If you can't, get a better cut off blade. Seriously, it's aluminum...run it faster. Use coolant.

E

yardbird · May 7, 2015

EM112358 said:
Aren't we all just a little gay?

E

Nope! Not even a little bit.

You might try to rig up a coolant line that gets the coolant right on the tool all the way to the bottom if you can, should help. I agree a better blade should fix most of your troubles and get the feed up there a bit.

Brent

litlerob1 · May 7, 2015

EM112358 said:
Aren't we all just a little gay?

Only on the weekends :smitten:

Monday through Friday it's no peck and feed hard enough that the chip arcs inward narrower than the width of the groove. A real grooving tool is going to make all the difference with that chatter one like this one; DOVE IQ GRIP

Robert my ±2

6061Mike · May 7, 2015

litlerob1 said:
I agree with Phil, pecking a groove is gay unless it's like a 1" peck. It causes the blade to deflect from side to side also. Also grooving with a part off tool is gay. But if you are only out 1.3" and getting a new holder----get a proper grooving tool not a part off tool, use them shits for what they are parting OFF.

Robert my ±2

LoL. What else can i say about this? Parting blades work fine for grooving. Grooving tools yes are better for grooving and even small diameter parting, but not absolutely needed. Just ran some 6061 parts that I profiled (grooving if you will) the whole backside then came in and parted off. No problems whatsoever, held length within about .002" on the part off. The profile that I was finishing was within .001" every time. There is stock on the back for facing, but I am talking repeatability. Oh, 3" diameter parting to a 3/8" center hole. Just don't leave your blade hanging out 1.5" for every thing you do and you should be fine. Sounds like your blade is shot though. What style are you using? The self grip that just push in? I am, using the tang grip from Iscar, so far so good, and it profiles pretty good if you leave minimal stock.
I am also using a parting blade with a .118 insert, 1.25 tall. I also peck when grooving. Maybe not needed, but if you keep your retracts to a few thou you should not see any movement of the blade or scoring from chips building up.

adama · May 8, 2015

If you can get a holder for the 32mm high blades, its a night and day difference compared to the 26mm height blades. Theres so much more metal under the insert actualy supporting - stabalising it. They take a lot more force to fail especially as stick out increases.

IMHO im not a fan of groveing with GTN inserts, depth - keeping them in a used holder becomes unreliable, yeah in alloy you may get away with it and with a newer holder for a fair while at that, in stainless or tougher steels its a real bad idea. Far better to go for one of the positively clamped insert styles if you can. It just gets rid of a bunch of variables that can bite you and also ensures a pretty constant grove depth on insert change, not something GTN holders are good at!

holows88 · May 22, 2015

Just to update ('cause I hate it when folks just disappear after getting the advice they need, too), Phil's suggestions worked out just fine. I replaced the parting blade, the inserts held up just fine, the diameter on the groove held within .001"

Still had a junk finish on the face, but just left a little extra and cut it down in the mill. Customer was happy, which means 1) I get paid, and 2) we stay in good graces.

Thank you everyone!

yardbird · May 23, 2015

Thanks for the update. Glad things worked out for you.

Brent

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