Compute the table feed rate for milling from feed per tooth, number of teeth and spindle speed, with the chip load and material removal rate.
Page last changed 2026-10-19 · based on n/a — standard engineering relationships, no single governing revision
Quick Answer
Table feed is F = fz · z · n — feed per tooth × number of teeth × RPM. Note that feed rate is independent of depth and width of cut; those change the material removal rate and the load on the tool, not the feed.
Milling Feed Rate
The Formulas Used
Table feed: F = fz · z · n where fz = feed per tooth, z = number of teeth, n = spindle speed Material removal rate: MRR = ap · ae · F Feed per revolution: fr = fz · z
Feed Rate Is Independent of Depth of Cut
The table feed depends only on chip load per tooth and spindle speed. Depth and width of cut change how much material is removed per minute and how much force the tool sees, but they do not change the feed — that is set by the chip the tooth has to take.
This trips people up because it feels wrong: surely a heavier cut should be fed slower? It should not, and feeding slower on a heavy cut is what causes rubbing, work hardening and short tool life. If a heavy cut overloads the tool, reduce the speed or the depth, not the feed per tooth.
Frequently Asked Questions
How do I calculate feed rate for milling?
F = fz × z × n — feed per tooth times the number of teeth times spindle speed. A 4-flute cutter at 0.004 in per tooth and 2,000 RPM gives 32 in/min, or about 813 mm/min.
Does feed rate change with depth of cut?
No. Feed rate is set by the chip load per tooth and the spindle speed. Depth and width of cut change the material removal rate and the cutting force, but reducing the feed on a heavy cut causes rubbing rather than helping.
What is chip thinning?
When the radial width of cut is less than half the cutter diameter, the actual chip is thinner than the programmed feed per tooth suggests. Increasing the feed to compensate keeps the chip load at the intended value and prevents the tool from rubbing.
How do I convert feed rate to mm/min?
Multiply by 25.4. A feed of 32 in/min is 813 mm/min. In metric practice the feed per tooth is given in mm and the arithmetic is the same.
Why does the calculator have a fixed chip thinning output?
Because chip thinning depends on the radial engagement and the cutter diameter, which are entered separately. The field is shown as a reminder that the programmed feed may need raising when the radial engagement is small — take the correction factor from your tooling catalogue.
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