Spindle Speed Calculator

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Surface speed at the cutting edge. Use the material reference table below for recommended values. Metric: m/min. Imperial: surface feet per minute (SFM).
m/min
On a mill: the cutter diameter. On a lathe: the part (workpiece) diameter at the cutting point.
mm
Number of cutting edges on the tool. Used to compute feed rate. Typical end mills: 2, 3, or 4 flutes.
flutes
The thickness of chip removed per tooth per revolution. Typical values: 0.02-0.10 mm for end mills in aluminum; 0.010-0.050 mm in steel. Lower values for harder materials or finishing passes.
mm/tooth
Affects suggested cutting speeds in the reference table below.
Spindle speedMedium RPM (general purpose)
1,910RPM

Revolutions per minute for the chosen cutting speed and diameter

Feed rate381.97
Feed rate unitmm/min
Surface speed (check)120
Surface speed unitm/min
1,910 RPM
Very low<100Roughing100-1000General1000-5000High-speed5000-15000Micro15000+

Spindle speed: 1,910 RPM

  • A 20 mm diameter tool at 120 m/min needs 1,910 RPM.
  • With 4 flutes and a 0.05 mm/tooth chip load, the table feed is 382 mm/min.

Next stepCross-check against your machine spindle maximum RPM. If the result exceeds your machine limit, reduce cutting speed (use the material reference table below) or increase tool diameter.

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