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CNC Turning Speed, Feed & Power Calculator

Spindle speed, feed rate, MRR, cutting force, power and theoretical Ra.

Metric · IS practiceFormula shown with your numbersNothing stored

How this calculator works

Spindle speed follows from the cutting speed you want and the diameter you are cutting. Feed rate in mm/min is feed per revolution times rpm. Material removal rate is the product of cutting speed, feed and depth of cut. Cutting force uses the specific cutting force of the material, and spindle power follows from force times cutting speed. Theoretical surface roughness is set by feed and nose radius alone.

Formulas used

Spindle speedn = Vc × 1000 ÷ (π × D) (rpm)
Feed rateVf = f × n (mm/min)
Material removal rateMRR = Vc × f × ap (cm³/min)
Cutting forceFc = kc × ap × f (N)
Spindle powerPc = Fc × Vc ÷ 60000 (kW)
Theoretical roughnessRa = f² ÷ (32 × r) (µm)

Checked against

Vc 220 m/min on Ø80 gives 875 rpm and 3.67 kW at 2.5 mm depth of cut and 0.25 mm/rev.

Worth knowing

Specific cutting force kc rises sharply at small feeds, so the force and power figures are conservative at fine finishing feeds. Recommended cutting speed bands for CNMG, TNMG and VNMG inserts are shown for each material.

CNC Turning Speed, Feed & Power Calculator — common questions

How do I calculate spindle rpm for turning?
n = Vc × 1000 ÷ (π × D). For a cutting speed of 220 m/min on an 80 mm diameter, that is 220000 ÷ 251.3 = 875 rpm.
What feed gives a 1.6 µm surface finish?
Theoretical Ra = f² ÷ (32 × r). With a 0.8 mm nose radius, a feed of 0.2 mm/rev gives about 1.6 µm. Real finish is worse than theoretical because of vibration, built-up edge and tool wear.

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Contact

Chennai, Tamil Nadu

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+91 91763 23669

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Eshwar C S

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T-231 A, Sidco Women's Industrial Park
Kattur, Avadi, Chennai – 600 062
Tamil Nadu, India

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33DENPP4793D1Z5

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