Chip formation theory in metal cutting describes how machining removes material as a permanent-deformation failure process whose mechanism differs by material behavior: ductile materials form continuous chips through a layer-by-layer shearing/yielding process along a shear plane (modeled by the card-analogy/Piispanen model), while brittle materials form discontinuous chips through crack initiation and brittle-fracture propagation ahead of the tool. The theory formalizes geometric descriptors of continuous chip formation — the chip-reduction coefficient (or its reciprocal, the cutting ratio), the shear-plane angle, and cutting strain, each related to rake angle and chip-tool friction via the Ernst-Merchant/Krystof-type relations — and the built-up-edge phenomenon (an adhesion-driven, cyclical welding-and-shearing process at the chip-tool interface), belonging to the mechanics-of-machining branch of manufacturing/production engineering.
Chip formation theory in metal cutting describes how machining removes material as a permanent-deformation failure process whose mechanism differs by material behavior: ductile materials form continu…