Chips.
Blue, Black, sometimes on fire. Keep the energy in the swarf.
Coolant quite often heat treats the swarf and th HP can go UP.
Try it dry.
To much fire? Reduce the speed.
Don't try to take less than 5 thou. DOC.
2 to 5 thou per rev feed, sort of whistling noise quite normal.
Can be spectacular on 6 foot diameter rock crusher cones! Heh Heh.
If you have problems keeping inserts in one piece you need ceramic inserts.
Round ones are are good. The have lots of faces!
Hope (for your sake) it is not an intermittent cut.
Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.