Finish Turning

[chet470]

I'm trying to get additional perspective on the concept of finish turning (rough & finish turning) vs. using one tool to remove all the mat'l. I have a preferred method but it seems that every other shop has a different preference. In the scenario the work piece would be would be short enough that it would not fall out of the guide bushing and the material would be 303ss.
What are your preferences and why? Thanks

[MikeMc]

I don't ever remember rough turning 303ss, but I suppose it would depend on the part and depth of cut.

[petriej]

We turn everything one pass and have no problems as long as you are mindful of your F/S. I don't care to pull in and out of the guide bushing to rough and finish - even if you have a maximum land GB.

[lukehonor]

Roughing and finishing on 303 in one pass, huh? I was turning a bar of 1.25" down to .517" over a length of 2.7". The material was 303SS. There's no way any tool out there would rough and finish in one pass and sustain tool life and finish. I was running this on a Tsugami SS32 and had to take 2 roughs and one finish. I still moved the bar back and had to get a collet from Hardinge that was coated with some sort of "carbide dust or powder" to grip better.

I like to rough with a CCGT or CCMT Sumitomo or kennametal insert. You'll want to use a beefy tool and a large radius insert. Then, I'll go in with a ground insert (CCGT Sumitomo) with a smaller radius.

If you have a shallow D.O.C., this is not necessary. Speak with your tool rep person and look into Sumitomo for rough and finish turning.

Good Luck!!

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

[cogsman1]

303ss is BUTTER!
I run a family of parts that is made out of 17-4PH and we go from 1.240" stock to .550" IN ONE SLOW PASS.
We had a lot of insert failures in the begining but hit upon an insert made by Utilities, sold by GenSwiss.
INSERT= Utilities# DNGU1104015 FNA4 UHM30HX
RPM= 1200
IPR= .002
Length of cut= 5.200"
MACHINE= CITIZEN M332Y
Coolant= Blaser Vascomill 22
CoolBlaster Hi pressure coolant pump @ 1700psi
We do have to use an optional stop to be sure the chips do not get tangled around the part. Happens once in a while.

HINT on clamping problem. Have your main spindle collet made with MORE slots to get stronger clamping. I have used 6 slots in the past. Not this job, the M32 doesn't need any help.

[dookie2022]

For extra material grip this maybe of help (SZM-Longstar)
SZM Spannwerkzeuge GmbH: SZM-Longstar
Nothing new about the idea but they make collets that suit the more popular spec machines.
As they are made in europe and we usually go through a UK company floyds automation to purchase as they do not sell direct
Not cheap but gets the job done when dealing with heavy cutting