Need Help!- Turning Small I.D.

[Tornos100]

I am turning a part on a citizen L20(7m8) that is 1.200 long out of titanium(6AL-4V). It has an .018 I.D. and the O.D. is .0225 at the front which tapers up to .0250 at a length of .930. I am running the spindle at 7500 and turning the length with a .0002 feedrate. The insert I am using has a .005 radius(kennametal T220F). Any suggestions to keep the part from bending durning the turning operation would be greatly appreciated. THANKS

[g-code_junkie]

turn a short length and then support with sub or one of the 21-23 stations (g650 or g620 mode).I sometimes have to use a lower rpm in order to cut down on vibration depending on how straight the stock is.
good luck

[lukehonor]

I have a continually running job in which I have to turn 303S.S. down to .051 over a length of 1.2. I had a lot of problems with this bending; during turning and cutting off/picking off. I had to make sure I was on center then I had to get a very positive insert with a sharp radius to turn this. Secondly, I made sure I was picking of as close as the machine would allow. I had a special extended nose collet made with a nice taper so my cutoff tool would almost bump the pickoff. I had a gap of approx .015" between cutoff and pick off.

Also, make sure you have very straight bars if you're running 7500 RPM's or else you're going to have some serious whipping that will reflect in your turning. I had to feed at .0005" with a speed about 3500.

303 is not like titanium, but hope this helps.

Good Luck!

Screw Machine Shop - Screw Machine Parts and CNC Machining - Progressive Turnings -

[dwolfhope]

The T220f has 0 degree relief on the side of the insert . You may want to try a TPGT21505HP in grade KC5010.this insert has 11 degrees side relief . This will reduce side pressure and help with the part not wanting to push away.

[cogsman1]

When you get the pickoff in to grab hold of the part, close the collet and then pull on the part slightly, you will have to find the correct amount of pull, the continue turning. This has worked for me in the past.

[ProProcess]

Originally Posted by cogsman1 When you get the pickoff in to grab hold of the part, close the collet and then pull on the part slightly, you will have to find the correct amount of pull, the continue turning. This has worked for me in the past.

+1 for me too, that is a good tip that has saved the day more than once!

[cincom]

hello

attached file is drawing, the mat'l sus304l, the problem is roughness, hard to reach Ra0.4. could you give me ideas what tooling brand is suitable this kind of mat'l, or other good suggestions. thank you.



cincom

[ProProcess]

Originally Posted by cincom hello attached file is drawing, the mat'l sus304l, the problem is roughness, hard to reach Ra0.4. could you give me ideas what tooling brand is suitable this kind of mat'l, or other good suggestions. thank you. cincom

This is a different subject entirely, you should contact a moderator and have it moved.
This will assure that this thread does not get off track and assure that you get your question answered.

[hacdlux]

Originally Posted by dwolfhope The T220f has 0 degree relief on the side of the insert . You may want to try a TPGT21505HP in grade KC5010.this insert has 11 degrees side relief . This will reduce side pressure and help with the part not wanting to push away.

i agree with wolf, i have had very good luck with the c version of that insert in TI, the other tool i have good luck with is an applitec 762x-tialn they no radius but it does have a wiper

[glenthemann]

less rad, sharper insert.