[penjas14]

Does anyone have any input on which would be better for finishing operations on a CNC Lathe, a 35 degree or 55 degree tool. The materials being machined all fall in the plain carbon steel and free machining steel category (1018, 1117, 1144)

[HuFlungDung]

You can finish with almost any insert shape, and the feedrate depends partly on the nose radius of the insert. The prime reason to choose a more acute point angle is to cut profiles that require that insert shape to create clearance.

For regular cylindrical turning and facing, I use CNMG extensively. This insert is capable of turning and facing with one toolholder in one station.

[PixMan]

You can get inserts for the 55 degree holder (assuming they're DNMG style) which employ wiper flats for improved finish at higher feed rates.

The best one out there right now (IMHO) for those steels would be the Valenite DNMG 432WN3 (wiper) in the new VP5615 grade. You should be able to run in the 800 to 1200 sfm range for those materials and get really nice finishes at feed rates in the .005-.022 ipr range.