[MantoolMike]

I have a project to turn a 5", 4mm X 4mm, OD groove with a finish requirement of 12Ra in ductile. Looking for any ideas on applications or inserts to get the finish.

Any recommendations would be appreciated.

[ToolHIT]

Yikes, that is a tough one. The best option I can think of is a 4mm Width Stub Grooving Insert that is either Cermet or Ceramic (the Harder Cermet or Ceramic Substrate will give a much better finish than Carbide). To get a better finish you will want to feed it very slow (.001"-.002" IPR) and run it at a high SFM (600-1,000 SFM). With the part being 5" Diameter that would be 458 to 764 RPM. How do you feel spinning a part that large that fast on your lathe?

A 12 Ra is an extremely good finish so even the Cermet or Ceramic Insert at the Higher SFM and low feed rate may not get there. You will most likely need to hand polish after. But it would give you the best possible finish you could get grooving it on a lathe. If you would like more information on this let me know!

Sorry I'm not much better help!

Mike