The amount each tooth advances into the work per revolution, the number that actually decides chip thickness and edge loading. Feed rate equals rpm times number of flutes times chip load, so a three-flute endmill at 6,000 rpm and 0.003 in per tooth feeds 54 in per minute. Too low a chip load rubs and work-hardens; too high chips or breaks the edge.
Chip load's way too light, it's rubbing, not cutting, double the feed and it'll quit squealing.
Also heard as
- feed per tooth
- IPT
- fz
Related terms
Feeds and speeds
The spindle speed and feed rate chosen for a cut, set from material, tool and machine.
SFM
Surface feet per minute: how fast the cutting edge moves across the work, the basis for spindle speed.
Rubbing
A tool sliding over the work without taking a proper chip, usually because the feed is too light or the tool is dull.
Work hardening
Hardening of a metal surface by plastic deformation, which makes the next cut much harder on the tool.