Threading stainless

[desmotom]

Have trouble with chatter on threading stainless 1.1258tpi its tougher grade of stainless not sure exactly what grade not called out on drawing

 

N10(THREADING )

(USE SANDVIK THREADING INSERT 8 TPI)

(USE SANDVIK THREADING HOLDER)

(TOOL PROTRUSION)

( UPPER TURRET )

( SUB SPINDLE )

G0G30U0W0

N6G55T1010

M414

G97S500M54

G18U0.W0.

G0G99X5.0Z-.1M8

X1.13

G76 P020160 Q0030 R.001

G76 X.9717 Z2.6P 0767Q0300 F.125

G0X1.6361

Z-.1M9

G0X5.0

G30U0W0

M5

M55

M71

G30U0W0

M115

M30

[jeff]

How far is it hanging out from the chuck?

Can you use a tailstock?

Have you tried more finish passes of about .001"?

[desmotom]

I am threading with a center. How would I go about adding finishing passes. I didn't know you could do that, I only added spring passes.

[Storkman]

Stainless can vary a lot depending on grade. Chatter?????? Sounds like 300 series. Is it non-magnetic??

[desmotom]

Yup its magnetic. How does my cycle look?

[elbro]

I would also try changing the infeed. Change your P020160 to P020130. Sometimes just changing the angle will help with chatter.

[jeff]

quote:

---

How would I go about adding finishing passes

---

On a Fanuc, the only way that I can think of is this:

G76 P020160 Q0030 R.001

G76 X.9737 Z2.6P 0767Q0300 F.125

G76 P020160 Q0030 R.001

G76 X.9727 Z2.6P 0767Q0300 F.125

G76 P020160 Q0030 R.001

G76 X.9717 Z2.6P 0767Q0300 F.125

 

But increase your depth of cut on the last 2 so it only takes the final passes

[desmotom]

I had tried it a 29 angle but I had the same results. What about rpm?

[heavychevy2155]

I would go with 800 rpm, P030055 the 03 is the number of spring passes 00 is the pull out angle 55 is the infeed angle.

[heavychevy2155]

This may sound weird but if I'm having problems with chatter I try something off the wall, maybe take a huge finish pass or some slow rpm. just something off the wall, 9 out of 10 times it works. Does you insert have a chipbreaker?

[desmotom]

Yeah the have a chip breaker. They are full form insert. I used three spring passes and 60 angle. It seems to be good but not great. Using a 55 degree pull out angle effect my thread form?

[horsepowered]

Try a positive rake insert and make sure that your insert is not above center. I usually put a threading insert about .002 below center. A lot of stainless steels will work harden from machining and you need to get under that hardened surface so I would not take any light passes. I would use .005 as my finish pass. Infeed angle 30 degrees not 29. Make last pass zero infeed to clean front and back. 800 is a good speed or slower if part is extended.