Finishing cobalt ball end mills create a finer finish on the workpiece than roughing ball end mills. Cobalt end mills can be used at higher speeds and are harder and more wear-resistant than high-speed steel end mills. Also known as ball-nose end mills, ball end mills have a rounded nose and create a round-bottomed groove in milling tasks. They are rotated against a workpiece to make round-bottomed slots and pockets or mill complex shapes without sharp corners.