Symbols and Measurement Units

D = Diameter of milling cutter (inches)
d = depth of cut (inches)
F = Feed rate (inches per minute)
ADV/R = Advance per revolution (inches)
f = feed (inches per tooth)
K = Power constant of work material
MRR = Metal Removal Rate (cubic in./min.)
rpm = revolutions per minute (cutter spindle)
Z = Number of teeth in the cutter
sfm = surface feet per minute
W = Width of cut (inches)
HPc = Horsepower at the cutter
HPm = Horsepower at the motor
DBT = Distance between teeth (inches)
E = Spindle efficiency (varies from 75% to 90%)

Milling Formulas

sfm = .262 x D x rpm
rpm = 3-82 x sfm
F = x z x rpm
f =
F
Z x rpm
ADV/R =
F
rpm
MRR = W X d x F
DBT =
3.1416 X D
Z
HPc =
3MRR
K
HPm =
HPc
E
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