Cutting Speed Calculator
Calculate the spindle RPM required for a desired cutting speed and workpiece diameter on a lathe or mill.
Required Spindle Speed
637 RPM
Required Spindle Speed vs Cutting Speed (Vc)
Formule
## Cutting Speed to Spindle RPM Cutting speed is the velocity at which the tool edge moves relative to the workpiece surface. ### Formula **N = 1000 Vc / (pi D)** where Vc is the desired cutting speed in m/min and D is the workpiece (or cutter) diameter in mm. The factor 1000 converts metres to millimetres. Recommended cutting speeds depend on the tool material and workpiece material combination.
Exemple Résolu
Turning a 50 mm diameter steel bar at 100 m/min cutting speed.
- 01N = 1000 x 100 / (pi x 50)
- 02N = 100,000 / 157.08 = 637 RPM
Questions Fréquentes
What cutting speeds are typical for steel?
HSS tools: 20-40 m/min. Carbide tools: 80-200 m/min. Ceramic tools: 200-500 m/min. Coated carbide: 100-300 m/min. Always consult the tool manufacturer for specific recommendations.
Does cutting speed change with diameter during facing?
Yes. On a lathe during a facing cut, the diameter changes continuously. Ideally the spindle speed should increase as the tool moves toward the centre to maintain constant surface speed. CNC lathes do this automatically in constant surface speed (CSS) mode.
How does cutting speed affect tool life?
Higher cutting speeds increase temperature at the tool edge, reducing tool life exponentially (Taylor tool life equation). A 50% increase in speed might reduce tool life by 80% or more.
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