Serrations along the cutting edge act as chip breakers, so these end mills can remove large amounts of material at high speeds. With better heat and wear resistance than high-speed steel, these cobalt steel end mills can run at higher speeds and provide better performance on hard material, such as iron, hardened steel, titanium, and tool steel. Their square end makes them good for milling square slots and edges. All are noncenter-cutting for operations where the peripheral teeth do most of the work, such as shoulder milling, contouring, and finishing. They cannot be used for plunge cuts.

End mills with fewer flutes provide better chip clearance for high-volume, high-speed plunge, slotting, and roughing cuts; end mills with more flutes provide a finer finish and operate with less vibration when run at high speeds.