Broaching is a machining process in which metal is shaped by a long bar-shaped cutting tool with teeth, called a broach. The machine tool on which the broaching process is done is called a broaching machine. Broaching is similar to sawing or filing; but a broach is different from a saw or a file in that each tooth is raised several thousandths of an inch above the previous tooth. Thus a broaching operation is completed in only one stroke of the broach.
Broaches are referred to as either pull or push types, depending on how motion is imparted to them. Internal broaching increases the size or changes the shape of an existing hole. For example, a round hole can be broached to a square hole of the same side length as the diameter of the hole. Surface broaching shapes external surfaces.