Sources and scope for this page: Industry convention — no single governing standard (conventional usage, definitions vary between sources), covering the definition of depth of cut (ap). No independent source check is recorded for this page: the content rests on the sources listed and on the working shown on the page. How sources, methods and updates are recorded.
Definition
Depth of cut sets the cutting force and the volume of material removed, but it does not set the feed rate — that is determined by chip load and spindle speed. Confusing the two leads people to slow the feed on a heavy cut, which is exactly the wrong response.
For roughing, the aim is usually the deepest cut the machine and tool can take, because most of the heat goes into the chip and away from the edge. Many light passes generate more total heat and wear than one deep one.
Common misuse
Reducing the feed when the depth of cut is heavy. Reduce speed or depth instead — slowing the feed causes rubbing and work hardening.