Broaches can be categorized by many means:

• Use: internal, or surface

Surface broaches
The slab broach is the simplest surface broach. It is a general purpose tool for cutting flat surfaces.

Slot broaches (G & H) are for cutting slots of various dimensions at high production rates. Slot broaching is much quicker than milling when more than one slot needs to be machined, because multiple broaches can be run through the part at the same time on the same broaching machine.
Internal broaches
Solid broaches are the most common type; they are made from one solid piece of material. For broaches that wear out quickly shell broaches are used; these broaches are similar to a solid broach, except there is a hole through the center where it mounts on an arbor. Shell broaches cost more initially, but save cost overall if the broach must be replaced often because the pilots are on the mandrel and do not have to be reproduced with each replacement.

• Purpose: single, or combination

• Motion: push, pull, or stationary

• Construction: solid, built-up, hollow or shell

• Function: roughing, sizing, or burnishing

• Equipment MLS:horizontal or vertical

Horizontal units are easily adjustable, and the user can readily reach any of its parts.

Vertical machines save room and last longer.

If the broach is large enough the costs can be reduced by using a built-up or modular construction. This involves producing the broach in pieces and assembling it. If any portion wears out only that section has to be replaced, instead of the entire broach.

Most broaches are made from high speed steel (HSS) or an alloy steel; TiN coatings are common on HSS to prolong life. Except when broaching cast iron, tungsten carbide is rarely used as a tooth material because the cutting edge will crack on the first pass.

Broaching machines are relatively simple as they only have to move the broach in a linear motion at a predetermined speed and provide a means for handling the broach automatically.

A broaching machine is a specialty machine designed for machining, or finishing, the surface of metal parts. It consists of a work table or some other fixture to hold the part in place, a broaching tool and a drive mechanism.

It has cutting teeth arranged in one or more rows, according to Encyclopaedia Brittanica. A broaching machine is typically used to finish metal surfaces in commercial industries.

A typical broaching machine works by keeping the metal piece stationary and cutting its edge while rotating around it, according to Global Spec. Broaching machines work quickly. A job usually takes only seconds.

Parts of a Broaching Machine

• Work Table

  The work table, or fixture, serves to tilt and hold the part in place for broaching. The center of the part and the center of the broaching tool are typically aligned with an offset of 1 degree, which creates a scalloping effect on the metal surface.

• Broaching Tool

  A broaching tool is a cutting tool with graduated cutting teeth arranged in a row. Each of the cutting teeth removes only a fraction of an inch from the surface of the metal, but, as the teeth become progressively higher, more and more metal is removed.

• Drive Mechanism

  The drive mechanism of a broaching machine is typically hydraulic or electromechanical. In either case, its purpose is to push or pull the broaching tool across the surface of the part. The part, itself, remains stationary.

• Types

  Broaching machines are either horizontal or vertical, according to Equipment MLS. Horizontal units are easily adjustable, and the user can readily reach any of its parts. Vertical machines save room and last longer.

• Applications

  Broaching machines are common tools in the electrical, automotive and aerospace industries. They must meet industry specifications. Manufacturers use them to make metal stampings, for forging and casting processes and to make machine parts.