Boring, refers to the forged, cast or drilled holes for further processing. Boring can expand the hole diameter, improve accuracy, reduce surface roughness, but also can better correct the original hole axis of the skew. Boring can be divided into rough boring, semi-fine boring and fine boring.

Boring is a method of machining on a prefabricated hole with a cutting tool to make it enlarged, and the boring work can be carried out either on a boring machine or on a lathe.