What is Broaching?
Broaching is a machining process that pushes or
pulls a cutting tool (called a broach) over or through
the surface being machined. Broaches are referred
to as multiple-point linear-travel cutting tools
and are used to produce flat, circular, and even
extremely intricate profiles, as seen from a section
perpendicular to the tool travel.
A broach is a series of single-point tools arranged
successively in the axial direction along a tool
body or holder. Each sequential tooth varies in
size and shape in a manner that allows each tooth
to cut a chip of the proper thickness.
The shape and spacing of each
broach tooth is determined by the length of the
part being broached, the amount of material being
removed by each tooth, and tonnage restrictions
of the broaching machine. The chip space between
each tooth is designed to sufficiently accommodate
the volume of chips generated.
The concept of broaching as a legitimate
machining process can be traced back to the
early 1850s. Early broaching applications
were cutting keyways in pulleys and gears.
After World War 1, broaching contributed to
the rifling of gun barrels. Advances in broaching
machines and form grinding during the 1920s
and 30s enabled tolerances to be tightened
and broaching costs to become competitive
with other machining processes. Today, almost
every conceivable type of form and material
can be broached.
Types of Broaches
The many different types of broaches available today
can be grouped into four major categories: