Chip Formation

Illustration of Chip Formation

When the cutting edge meets the workpiece, the material is deformed by shearing which results in one of three types of chip formation.

Discontinuous chips
Shavings arising from plastic deformation together with recurring fractures which give the chip a non-uniform thickness.
These chips are easily broken into smaller parts, which leads to less friction, better surface smoothness and easier chip removal. However, the fractures can give rise to vibrations that adversely affect the surface smoothness.
Caused primarily in brittle materials, larger chip thickness, at low speeds and low angles between the insert and the workpiece surface.

Continuous chips
Shavings arising from pure plastic deformation without fracture resulting in an even chip thickness. These provide minimal vibration which is good for the surface smoothness but with the disadvantage that the chips are often long and can interfere with the cutting process..

Continuous chips with built-up edge
Chips that occur like continuous chips but with the difference that cyclic built-up formations, deposits of the material that are built til they brake and ar re-build again, results in decreased surface smoothness.