Cutting condition Formula for Turning

※ Cutting Speed (vc)


*Divide by 1000 to change to m from mm.
Vc (m/min) : Cutting speed
Dm (mm):Workpiece Diameter
π (3.14): Pi
n (min-1):Main Axis Spindle Speed



※Cutting Power (Pc)

Pc= Ks×Vcxap×Xf / 6120×η

PHP= Ks×Vcxap×f / 4500×η

Pc(kW):Cutting power
PHP(HP):Cutting power
Vc(m/min):Cutting speed
ap:Cutting depth
f(mm/rev):Feed rate per minute of table
Ks (kgf/mm2):Relative cutting resistance
η(0.7~0.8):Mechanical efficienc


Approximate rate (Ks)
Mild Steels 190
Medium Steels 210
Hard Steels 240
Light Alloy 190
High Alloy 245
Cast Iron 93
Forging cast iron 120
Bronze / Brass 70


※ Theoretical finished surface roughness(Rz)


Rz(h):Theoretical finished surface roughness
f(mm/rev):Feed rate per minute of table
R(rε):Nose Radius



※Chip removal Volume (Q)

Q(cm3/min): Chip removal Volume
Vc(m/min):Cutting speed
ap(mm):Cutting depth
f(mm/rev):Feed rate per minute of table

※Cutting Time (sec)

Tc = Im/I (min)
Tc(min) : Cutting Time
Im(inch) : Workpiece Length
I(inch/min) : Cutting Length per Min