Turning 321 Stainless

[Bill308]

I was wondering if anyone had any ideas or suggestions for inserts or feeds/speeds for turning 321 SS. Its a 14" diameter flame cut slug with a through hole and has an interrupted cut on the od and id. we use CNMG 432TP400's on both but they dont last but 3 parts tops! the first path uses an 80 deg holder and opposite corners of the insert


N12 (R/FACE)
G54
G28
T12 (ROUGH FACE)
M41
G50 S720
G97 S400 M03
G00 Z1. M08
X14. Z0.5 M31
G96 S325
G01 Z0.11 F0.1
X3. F0.012
G00 W0.05
X14.
Z0.06
G01 X3.
G00 W0.05
X14.
Z0.01
G01 X3.
M09
G00 Z1.
G28
M05
M01

N2 (R/T&F)
G28
T2 (R/TURN OD)
M41
G50 S720
G97 S400 M03
G00 Z1. M08
X14. Z0.5 M31
G96 S200
X13.5 Z0.1
G71 P10 Q11 U0.015 W0.01 D0.05 F0.01
N10 G00 X12.3
G01 Z0 F0.01
X12.3645
G03 X12.441 Z-0.0383 R0.0383
G01 Z-0.975
N11 G00 X13.5
G00 Z1. M09
G28
M05
M01

Thanks ANY ideas would great!
Bill

[eorourke]

It appears that you are running at 325SFM at .010" PR. There are two issues:
1. the material is flame cut which means that it is work hardened and has scale. 2. You say that there is interruption in the cut.

I would use the 100 degree corner of the insert and rough face, index the turret and rough turn the O.D. with the 100 degree corner of another insert if you are not going up to a shoulder. I would use an insert with a TIALN coating and a strong but free cutting chip breaker designed to machine SS. I would also consider using a bigger nose radius such as CNMG 433 or even a bigger insert such as a CNMG 543 and take a bigger DOC.(depth of cut) and reduce the # of passes. The failure usually happens at the nose and the nose only has so much life in it. The less times you have to pass it over the part, then the more parts you can machine with it. BTW, You could get away with .150" - .200" doc if you use the 100 degree corner.

[Bill308]

Yeah I think a CNMG 434 is the biggest insert we can stick in our current holders. Still trying to find a holder for the 543's. One of our tool vendors gave us some sample of different inserts so we'll see what happens with those. Good Ideas though!! Keep them comin'

Thanks
Bill

[DareBee]

I agree entirely with the above comments.
Doing 3 parts with 1 insert change is very good IMO.
Use a roughing cutter and a finishing cutter, just like mentioned above, I like to use the 100degree edge (that normally gets thrown out) for my roughing as well.

[eject_21]

On the turning path, make your first cut as far below the flame cut edge as possible. I've cut similar parts with good luck with a Mitsubishi us735 insert.as above, double your doc and cut your feedrate back if needed. Maybe take one cut at 13.2", F.006, then go into your G71 cycle. Getting below the flame cut portion on the first pass is key. How much of the cut is interupted? If it's more than 20% you may have better luck running it dry.3 parts per edge is pretty respectable though! good luck!

[Bill308]

I want to thank everyone for the responses! We are getting ready to start a new run and we have the 543 inserts. We also changed the roughing passes to face instead of turn(more stabilty). So we will see how she runs!!

Thanks!
Bill

[g-codeguy]

Originally Posted by eject_21 On the turning path, make your first cut as far below the flame cut edge as possible. I've cut similar parts with good luck with a Mitsubishi us735 insert.as above, double your doc and cut your feedrate back if needed. Maybe take one cut at 13.2", F.006, then go into your G71 cycle. Getting below the flame cut portion on the first pass is key. How much of the cut is interupted? If it's more than 20% you may have better luck running it dry.3 parts per edge is pretty respectable though! good luck!

In an attempt to limit the number of vendors supplying us with inserts, we no longer carry US735, but I also have had good luck with them in certain applications.

[Bill308]

Looks like the 543 coated did the trick! We used it to skim the face and get underneath the flame cut then went in with a 80Degree holder using the opposite corner of a 432 TP400 to rough the profile. Now if we could find one of those massive inserts with an 1.250 boring bar we would be in business!! Again thanks for all the awesome ideas guys!!

Later
Bill