Specialty Broaching Operations
Broaching is an extremely versatile machining process. There is a limitless amount of ingenuity that can be applied to arrive at the perfect combination of cutting tools, holding fixtures, and machine tools in order to perform the most complex of cutting technology for your workpiece. Here’s a couple of examples of non-traditional broaching operations used to perform special cutting tasks:
Continuous Chain Broaching
Continuous chain, or simply chain broaching refers to the type of machine that is used to broach a piece part. A chain broaching machine resembles a very long tunnel, through which passes a series of holding fixtures, or cars. Piece parts are loaded, usually automatically, into the cars, which themselves are mounted on, and carried through the tunnel by a very large continuous chain. The broach tooling is mounted on the inside walls of the tunnel, and this tooling cuts the piece part as it passes through the tunnel. Chain broaching is oriented towards high volume production, and is an extremely fast and efficient operation. However, because the fixtures used to hold the piece parts are mounted on chains that are driven by sprockets, it is difficult to hold extremely close tolerances. This process is suitable for high-volume, external cutting.
Multiple-pass broaching (i.e. two-pass, three-pass broaching) simply refers to the number of times a separate operation must be performed on a part to accomplish the desired shape and size. Sometimes the length of cut required on a part is too long to be accommodated by the passing of one broach alone. In that case two or more broaches are pulled or pushed through or past the part, each one cutting progressively more to the finished size. In other cases a particularly smooth finish is required on the part, and a ‘finishing broach’ is used after the part is cut largely to the required specifications. In still other cases, multiple dimensions are cut on a single piece, requiring the part to be indexed or turned in some fashion, before either the same broach or a different broach is used to cut the additional dimension.