Cutting Speed and Feed Calculator
Calculate spindle speed (RPM), table feed rate and material removal rate for CNC milling from cutting speed, tool diameter, chip load and number of flutes.
Spindle speed
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Feed rate
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Material removal rate
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Starting values only. Use the tool maker's recommended cutting speed and chip load for your tool, material and machine.
Formulas
- Spindle speed n = Vc × 1000 / (π × D)
- Feed rate Vf = fz × z × n
- Material removal rate Q = ap × ae × Vf / 1000 (cm³/min)
Cutting speed depends mostly on the workpiece material and tool coating: aluminum allows far higher speeds than steel or stainless steel. If the calculated RPM exceeds your spindle's maximum, run at the maximum RPM and keep the chip load, which lowers the feed rate.
FAQ
How do I calculate RPM for milling?
RPM = cutting speed (m/min) × 1000 / (π × tool diameter in mm).
What is chip load?
The thickness of material each cutting edge removes per revolution, in mm per tooth.