proven turning inserts for obtaining the best finish in 303 stainless?

[mbraddock]

Greetings.

I've got a job coming up where I need to obtain a nice cosmetic finish on some 1-1/8" diameter stainless steel parts. I'll be using a Doosan LYNX CNC lathe with good (water-based) coolant pressure and concentration, a collet chuck, and minimal part stick-out. The parts cannot be tumbled, as the customer wants them to be as shiny as possible. What type(s) of inserts have you had good experience obtaining a nice finish with in 303?

Thanks in advance for sharing your experience!

Mike

 

[EmGo]

At the risk of being repetitive, I'm a big fan of the knux in materials that like positive rake ...

 

[triumph406]

TPGT inserts work very well for me in 303.

Can't remember what coatings work well.

 

[Orange Vise]

Should be fairly easy to get a good finish in 303 given your setup. A CNMG431 or equivalent in a general purpose stainless grade from any name brand will work just fine.

For most consistent results, leave about 0.015" per side for the finish pass and stay at the top end of the recommended SFM range, and run your coolant rich.

 

[???]

How good can you get the finish. I tried to see if I could get a mirror finish by buffing a rod of 303 and it still looks like it's got inclusions. Material is from Valbruna so I assume it should be good. Tips I use are Iscar DCMT 3-1-SM IC807 unless I am chasing a really tight tolerance and then I will use DCGT 11T304-AS IC20. But take everything I do with a pinch of salt as I am a toolmaker not a production machinist.

 

[BT Fabrication]

all depends what tooling you can get, ive used a bunch of iscar with good results, just need to find the correct grade that you need for stainless.

 

[Mtndew]

If you have access to Sandvik, they have some good SS grades.
https://www.sandvik.coromant.com/en...grades/turning-inserts-grades-stainless-steel

 

[charlie gary]

I use NTK DT4VCGT110302MCL inserts on 303 a lot, and they deliver a good finish.

 

[Matt@RFR]

I'm not a lathe guy and I don't know what all your insert gobbly gook means, but when I want 'the best' finish on 303, I use aluminum-specific endmills. Maybe you can use an aluminum-specific insert for your finish pass?

 

[mbraddock]

I appreciate all the helpful replies and recommendations!

 

[CarbideBob]

I'm not a lathe guy and I don't know what all your insert gobbly gook means,

"insert gobbly gook"
I resemble that remark.

 

[rjwalker1973]

I use sandvick cnmg 432 On our 303 and have never had a problem getting a great finish.

https://www.dgisup.com/product/SVK7860892ply

 

[SageGlad]

I've never used any better inserts. They also lasts forever with right speed/feed.

 

[david n]

Meh...........it's 303. It finishes great with most any insert..............I bought a pack of cheapo(prolly chinesium) SS specific inserts a while back from Curtis(exkenna)...........CNG432. Good edge prep for SS. In 303 they run forever.......600+ SFM and .008/rev will give yah a purdy finish..........and like most finish turning..........take a decent cut. At least deeper than the TNR..................just finishin' up a few thousand lbs of 303 here.......I don't even have to try to get a good surface finish, it just happens all on its own.