[bobrob]

DO YOU USE COOLANT ? OR RUN DRY WITH OUT COOLANT ..? OI am tkaing off arox .015 per pass. surface feed of 300 spindle speed of around 400 rpm .

[pvellenga]

Run it dry for best results. The coolant will cause thermal shock and weaken your insert.

[HuFlungDung]

Yup, dry always. The chip should be red hot, that is when you know you are going fast enough. With that being said, I don't like to overshoot the 'just red' condition too far, as this can shorten tool life unnecessarily. Check that your ceramics are rated to machine the type of material in the condition you are cutting, as a mismatch rapidly leads to tool failure.

[Guldberg]

IMO you can easily crank it up. I just turned down a piece of tool steel (not hardend though) 80->20mm. 640rpm, 1.5mm on diameter per pass. I have a load of theses inserts, so wear didnt matter, but i didnt notice any anyway. Just watch out, the chips are razor sharp and burning hot (pretty blue). One landed on my neck causing a nasty nasty burn!

And as already pointed out. Without coolant. You want the temperature to be steady