We do lots of live tool engraving on our lathes in mild steel that gets painted over.
Use 3/32" CARBIDE BALL END MILL 2 FLUTE 1800332 from lakeshore carbide.
Limited to 3000 RPM on some of lathes and feed at 300mm/min, 1/2 that for plunging. We have a 3-1 speeder on one machine and run 3 times...