What is specific cutting force Kc?

Specific cutting force Kc (N/mm²) is the force per unit area of undeformed chip cross-section. It depends on material, chip thickness, and tool geometry. Typical Kc for steel is 1800–2500 N/mm².

How is cutting power calculated?

Pc = Kc × ae × ap × vf / (60 × 10⁶) kW, where ae is width of cut, ap is depth of cut (both in mm), and vf is feed rate in mm/min.

What is metal removal rate?

MRR = ae × ap × vf (mm³/min). It represents the volume of material removed per unit time and directly relates to cutting power.

How do I select a machine with sufficient power?

The machine spindle power must exceed Pc / η, where η is spindle efficiency (typically 0.7–0.9). Add 10–20% margin for safety.

Does Kc change with chip thickness?

Yes. Kc increases for thinner chips due to the size effect. Kc = Kc1 × h^(-mc), where Kc1 is Kc at 1mm chip thickness and mc is the material constant (0.2–0.4).

Free Engineering Tool #211

Cutting Power Calculator

Calculate cutting power for milling from specific cutting force, width/depth of cut and feed rate. Also shows metal removal rate (MRR).

Pc = Kc × ae × ap × vf / 60000Milling

Results

Cutting Power (Pc)

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Required Spindle Power

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Metal Removal Rate

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Cutting Power

Metal Removal Rate

Example — Face milling steel

Given: Kc = 2000 N/mm², ae = 10 mm, ap = 3 mm, vf = 400 mm/min

Pc = 2000 × 10 × 3 × 400 / 60,000,000 = 0.40 kW

MRR = 10 × 3 × 400 = 12,000 mm³/min = 12 cm³/min

Cutting Power Calculator | Pc = Kc × ae × ap × vf / 60000

Published by Nikolai Shelkovenko on February 15, 2026 February 15, 2026

Results

Cutting Power

Metal Removal Rate