Broach:
A broach is a multi point cutting tool having a series of cutting teeth or edges which gradually increase in size from the starting or entering end to the rear end. Broaches are used for machining either external or internal surfaces. These surfaces may be produced flat or circular. In broaching, the broach is pushed or pulled over or through a surface of work piece, Each tooth of the tool. A thin slice from surface broaching of inside surface is called internal or hole broaching and outside surfaces is called surface broaching.
Detail of an internal or hole broach:
A typical broach is shown in figure.
It is used to machine an internal hole. The broach is gripped by puller at the shank end. The front rake angle refers a rake angle of a single point cutting tool and back of the angle (relief angle) is provided to prevent rubbing of the tool with the work piece.
High speed steel (Hss) material is widely used to make the broach. It is also raised carbide of disposable inserts or sometime used for cutting edges then machining cost iron parts, which requires close tolerance. Carbide tools are also used to an advantage on steel cutting. A broach may be either assembled or built up form shells.