How to use it
- Choose the units and enter the cutting speed for your material and tool.
- Enter the tool diameter, the number of flutes and the chip load per tooth.
- Set your spindle’s maximum speed, and optionally the depth and width of cut, then read the RPM, the feed and the removal rate.
How it works
- spindle speed: n = Vc × 1000 ÷ (π × D) (Vc in m/min, D in mm), or n = SFM × 12 ÷ (π × D) (D in inches);
- feed rate: F = n × flutes × chip load;
- material removal rate: Q = depth of cut × width of cut × F.
If n is above the spindle maximum, the calculator uses the maximum and recomputes the cutting speed from it.
Example
A ½-inch 3-flute end mill at 600 SFM with a 0.002 in chip load:
- n = 600 × 12 ÷ (π × 0.5) = 4,584 RPM;
- F = 4,584 × 3 × 0.002 = 27.5 in/min;
- with a 0.25 in deep and 0.1 in wide cut, Q = 0.25 × 0.1 × 27.5 = 0.688 in³/min.
In metric, a 10 mm cutter at 200 m/min turns at 6,366 RPM and feeds 955 mm/min at 3 × 0.05 mm, removing 9.55 cm³/min with a 5 × 2 mm cut.
Tips and common mistakes
- Chip load is per tooth: doubling the flutes at the same feed halves it, and too small a chip rubs instead of cutting.
- For light radial cuts, tool makers often suggest raising the chip load to make up for chip thinning; follow their tables.
- Small cutters on a router often hit the spindle limit. Then feed drops with the speed if you want to keep the chip load.