CNC Turning Machine Power Calculator

Calculate net cutting power, estimated machine input power, cutting force and metal removal rate for CNC turning. Enter your cutting parameters or load the example to begin.

Turning Parameters

Enter metric inputs. The specific cutting force is material- and tool-dependent; use a suitable value from your cutting-data reference.

Depth of Cut (a_p) mm Feed per Revolution (f_n) mm/rev Cutting Speed (v_c) m/min Specific Cutting Force (k_c) N/mm² Example only: 2,000 N/mm² is not a universal steel value. Machine Efficiency (η) % Enter a value above 0% and no greater than 100%.

Calculation Results

Enter all five parameters to view results.

These are theoretical estimates for a steady turning cut, not measured machine power or a guarantee that your machine can perform the operation.

CNC Turning Power Formulas

Net cutting power is the mechanical power needed at the cutting edge. A separate efficiency adjustment estimates the input power needed to supply that cutting power.

P_c (kW) = (a_p × f_n × v_c × k_c) / 60,000
P_m (kW) = P_c / (η / 100)
F_c (N) = a_p × f_n × k_c
Q (cm³/min) = a_p × f_n × v_c

Here, a_p is depth of cut (mm), f_n is feed per revolution (mm/rev), v_c is cutting speed (m/min), k_c is specific cutting force (N/mm²), and η is machine efficiency in percent.

Turning Power Calculation Example

Assume a depth of cut of 2 mm, feed of 0.30 mm/rev, cutting speed of 200 m/min, specific cutting force of 2,000 N/mm², and efficiency of 80%.

Net cutting power: (2 × 0.30 × 200 × 2,000) / 60,000 = 4.00 kW.

Estimated machine input power: 4.00 / 0.80 = 5.00 kW.

Estimated cutting force: 2 × 0.30 × 2,000 = 1,200 N.

Metal removal rate: 2 × 0.30 × 200 = 120 cm³/min.

Frequently Asked Questions

What is the difference between cutting power and machine input power?

Cutting power is the power required at the tool–workpiece interface. Estimated machine input power is cutting power divided by assumed efficiency; it is not the machine's measured electrical consumption.

Where can I find the specific cutting force (k_c)?

Use machining data from the tool manufacturer for the workpiece material and cutting conditions. The effective value depends on material, undeformed chip thickness, tool geometry and other conditions; the example is not a universal recommendation.

Can I use this result to select a CNC lathe?

Use it as an initial power estimate only. Also check available spindle power at the intended speed, torque, duty cycle, machine limits, interrupted cuts and tool wear before planning a production cut.

Specific Cutting Force Kc(MPa)

Work Material	Tensile Strength(MPa) and Hardness	Specific Cutting Force Kc(MPa)
Work Material	Tensile Strength(MPa) and Hardness	0.1 (mm/rev)	0.2 (mm/rev)	0.3 (mm/rev)	0.4 (mm/rev)	0.6 (mm/rev)
Mild Steel	520	3610	3100	2720	2500	2280
Medium Steel	620	3080	2700	2570	2450	2300
Hard Steel	720	4050	3600	3250	2950	2640
Tool Steel	670	3040	2800	2630	2500	2400
Tool Steel	770	3150	2850	2620	2450	2340
Chrome Manganese Steel	770	3830	3250	2900	2650	2400
Chrome Manganese Steel	630	4510	3900	3240	2900	2630
Chrome Molybdenum Steel	730	4500	3900	3400	3150	2850
Chrome Molybdenum Steel	600	3610	3200	2880	2700	2500
Nickel Chrome Molybdenum Steel	900	3070	2650	2350	2200	1980
Nickel Chrome Molybdenum Steel	352HB	3310	2900	2580	2400	2200
Hard Cast Iron	46HRC	3190	2800	2600	2450	2270
Meehanite Cast Iron	360	2300	1930	1730	1600	1450
Grey Cast Iron	200HB	2110	1800	1600	1400	1330

CNC Turning Machine Power Calculator