Turning Horsepower Calculator

Inputs

Work diameter (D)

Workpiece diameter at the cutting edge.

Cutting speed (Vc)

Surface cutting speed at the work diameter.

m/min

Feed per revolution (fn)

Turning feed per spindle revolution.

Depth of cut (ap)

Radial depth of cut.

Specific cutting force (kc)

Material/tool cutting-force coefficient. Use toolmaker data when available.

MPa

Machine efficiency (eta)

Allowance from cutting power to required spindle power.

Default result

Required spindle power(P_sp)

2.25kW

Cutting power divided by the entered machine efficiency.

Also computed

Cutting power(P_c)1.8kW

Material removal rate(Q)72cm³/min

Spindle torque(T)18.75N·m

Spindle speed(n)1,146rpm

Cutting force estimate(Fc)600N

Uncut chip area(A_c)0.4mm²

Method notes 3 notes

RPM = Vc * 1000 / (pi * D), with Vc in m/min and D in mm.
Turning MRR = cutting speed * feed per rev * depth of cut.
Specific cutting force changes with material, insert geometry, chip thickness, lead angle, wear and coolant. Treat this as a spindle-load screen, then verify against the machine load meter and tooling data.