Feed for milling is expressed as feed per tooth. When the table moves 100mm at 1,000 RPM, table feed is vf=100mm/min.
- Click on the links below to learn more about the most common formulas used when milling!
Cutting speed (vc)
Cutting speed is the speed of the peripheral cutting edge of the milling cutter.
It is the movement of the cutting edge across the workpiece in a minute. It is measured in metres per minute and can be calculated by a similar formula to turning’s.
(πDm) of the formula below is the periphery of the work. The periphery x n(RPM) is the amount of movement of the tooth per minute (mm).
Usually expressed in m/min. Divide by 1,000 to change from mm to m.
Table feed (vf)
Table feed is the amount of movement of the workpiece per minute.
The formula below is given by multiplying the said formula for calculating feed per tooth by z (the number of inserts) and n (RPM).
Feed per tooth (fz)
Feed per tooth for the milling cutter with several teeth is the amount of movement of the table from when one tooth comes to cutting position to when another tooth comes to cutting position.
Table feed per tool revolution can be found by vf (table feed)÷n (RPM).
As shown in the formula below, feed per tooth can be calculated by dividing table feed per tool revolution by the number of teeth.
Cutting time (tc)
Cutting time is the time required to machine the workpiece.
As shown in the image below, the milling cutter needs to machine the length of the workpiece. Therefore, total table feed length can be found by adding cutter diameter and workpiece length.
Cutting time can be found by L (total table feed length) ÷ vf (table feed).