Sources and scope for this page: Industry convention — no single governing standard (conventional usage, definitions vary between sources), covering the definition of radial engagement (ae). 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
Radial engagement drives chip thinning. When it falls below half the cutter diameter, the actual chip is thinner than the programmed feed per tooth suggests, so the tool rubs and wears rather than cutting.
The correction is to raise the feed to restore the intended chip load — this is what makes high-efficiency (trochoidal) milling possible, with small radial engagements and very deep axial cuts.
Common misuse
Running a light radial pass at the nominal feed per tooth. The chip thins, the tool rubs, and the finish and tool life both suffer.