Profiling dom tube insert recomedation

Im profiling 1018 dom tube need to use a vnmg 331 insert. The part is to long to use a larger radius due to chatter.
Can anyone recommended an insert they like in this size that has the geometry and grade get a very good finish in this material. I need to get under a 32 micro inch with the finish pass.

Also what is the difference between a 35 deg diamond and 35 deg Rhombic. Are the both the same.

I guess I am getting old It seems insert selection is getting harder to understand.

Thanks
Tim

Kallam said:

...Also what is the difference between a 35 deg diamond and 35 deg Rhombic. Are the both the same.

Click to expand...

A VNMG331 is a VNMG331. Doesn't matter if they call it a diamond or a rhombus. It's a VNMG331.

A 1/64 TNR @.004" IPR is a theoretical 32 finish. The trick is going to be getting the chip to break and not wrap around the insert and tear up the finish. I usually get better results leaving a little more for the finish pass rather than less.

It might help if you put a spud or pressure pad in the end and support it with the tailstock. That might allow you use a 332 insert and run a heavier chipload.

Most DOM is 1020, but it cuts the same as 1018, which is to say it cuts like shit. Gummy, stringy, doesn't like to break a chip on light cuts.

Any carbide grade for general purpose turning steel will be fine. Use what you have.

I've had some luck with cermet inserts and lots of RPMs. But, they don't like chatter. Mitsubishi makes some good ones.