Below is a list of Internal Broaching manufacturers from Waterloo, Iowa. Internal broaching is a broaching method that pushes a tool completely through the workpiece, as opposed to surface broaching, which produces a hole that cuts the surface of the metal. In order to internally broach a metal part, a pre-existing hole must be made. The broach then changes the shape and size of the starter indent into a hole with a keyway, spline, hexagonal, square or custom designed profile. A broaching tool that has successively larger and larger teeth pierces through the pre-existing hole by pulling or pushing through the metal part.