Machining Speeds and Feeds Equations & Calculator

Engineering Calculators | Engineering Metals and Materials

Machining Speeds and Feeds Equations Calculator

Machining operations may be conducted on machine tools having a rotating spindle or a rotating part (lathe). Cutting speeds are usually given in feet or meters per minute and these speeds must be converted to spindle speeds, in revolutions per minute, to operate the machine. Conversion is accomplished by use of the following formulas:

Open machining Speeds and Feeds Calculator

For Spindle velocity in rpm, the equation is:

N = 12V / 3.14157D for inch units
and
N = 1000V/3.14157D for metric units

Where:

N = Spindle speed in revolution per minute (rpm)
V = Cutting speed in feet per minute (fpm) or (meter per minute (m/min)

In turning operations, D is the diameter of the work piece; in milling, drilling, reaming, and other operations that use a rotating tool, D is the cutter diameter in inches for U.S. units and in millimeters for metric units. Reference π = 3.14157.

Cutting speed in fpm or m/min, the equation is:

V = 3.14157DN / 12 for inch units
and
V = 3.14157DN/1000 for metric units

Where:

N = Spindle speed in revolution per minute (rpm)
V = Cutting speed in feet per minute (fpm) or (meter per minute (m/min)
D = Cutter or work piece diameter

Open machining Speeds and Feeds Calculator