Sources and scope for this page: ISO 513:2012, covering the definition of flank wear. 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
Flank wear is gradual and predictable, unlike crater wear or chipping. That makes it the criterion most tool life standards use: the tool is spent when the wear land reaches a specified width, regardless of whether it still cuts.
It is caused by abrasion from the machined surface, so it accelerates in abrasive materials and in hard inclusions. Coated tooling exists largely to slow it down.
Common misuse
Judging tool life by surface finish alone. Flank wear may be well past the criterion while the finish still looks acceptable — until dimensions drift out of tolerance.