Milling Formulas

General Milling Formulas for Working with Carbide Tools, Engravers, End-Mills and Cutters

To Find	Using	Formula
SFM Surface Feet per Minute	RPM – Revolutions per Minute Dia – Diameter of End Mill	RPM ÷ 3.82 x Dia = SFM
RPM Revolutions per Minute	SFM – Surface Feet per Minute Dia – Diameter of End Mill	SFM x 3.82 ÷Dia = RPM
IPM Inches per Minute	RPM – Revolutions per Minute IPT – Inch per Tooth, Chipload # FL – # of Flutes	RPM x IPT x #FL = IPM
IPT Inch per Tooth, Chipload	IPM – Inches per Minute RPM – Revolutions per Minute # FL – # of Flutes	IPM ÷RPM ÷#FL = IPT
IPR/FR Inch (Feed) per Revolution	IPM – Inches per Minute RPM – Revolutions per Minute	IPM ÷RPM = IPR (FR)
MR Metal Removal Cubic Inches per Minute	ADC – Axil Depth of Cut RDC – Radial Depth of Cut IPM – Inches per Minute	ADC x RDC x IPM = MR
HP Horsepower Required	IPM – Inches per Minute RDC – Radial Depth of Cut ADC – Axil Depth of Cut PC – Power Constants	IPM x RDC x ADC x PC = HP