Calculate the horsepower required for a milling operation based on the feed rate and depth of cut, which are used to determine the material removal rate (or metal removal rate). Also required is the unit power, which is a material property describing the amount of power required to cut that material. The horsepower at both the spindle and the motor are shown, as well as the spindle torque for a given spindle speed (RPM). The motor horsepower required for the milling operation can then be compared to the horsepower capability of the machine.