What is a broach?

A broach is a piece of hard metal used to push through another piece of metal and leave a hole with a defined shape. Broaches can rely on a single chisel point or on a series of progressively taller chisel points mounted on one or more pieces of metal. Broaches are typically used to enlarge a circular hole into a larger noncircular shape such as a square or other desired shape.

4 mm hex custom broach

Leveraging broaching with CNC mills and large machining centres

Broaching has typically been done with broaching machines: large powerful single purpose pieces of equipment. The advent of large machining centres is giving rise to a more cost efficient way of broaching, making use of the downward force of the Z axis of a machining centre to push a broach through material.

Broach Design

Vancouver Wire EDM will help you take advantage of this overlooked resource in your large CNC mills, developing custom broaches to allow milling centres to serve as broaching machines. The obvious advantage is that the piece need not be handled by one operator to undergo the broaching operation. This reduces the number of changes of machine, saving money to the end user. It also allows users to cut shapes with a broach on a mill, which would be more time consuming, or technically challenging to cut with conventional CNC tools. The above photo shows an examples of broaches made for CNC mills.

Broaches are traditionally cut using a broach grinder, but a wire EDM can cut broaches in harder metals, more accurately and often, more quickly, leading to cost savings.