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Chapter 14/Tooling & Production
1
Metal Removal
Cutting-Tool Materials
Metal Removal Methods
Machinability of Metals
Single Point Machining
Turning Tools and Operations
Turning Methods and Machines
Grooving and Threading
Shaping and Planing
Hole Making Processes
Drills and Drilling Operations
Drilling Methods and Machines
Boring Operations and Machines
Reaming and Tapping
Multi Point Machining
Milling Cutters and Operations
Milling Methods and Machines
Broaches and Broaching
Saws and Sawing
Abrasive Processes
Grinding Wheels and Operations
Grinding Methods and Machines
Lapping and Honing
George Schneider, Jr. CMfgE
Professor Emeritus
Engineering Technology
Lawrence Technological University
Former Chairman

of their use for high production runs.
A two station broaching operation is
shown in Figure 14.1.
14.2 Broaching
Tooling is the heart of any broaching
process. The broaching tool is based
on a concept unique to the process -
CHAPTER 14
FIGURE 14.1: Typical broaching operation of an internal spline. (Courtesy Detroit
Broach & Machine Co.)
Chap. 14: Broaches & Broaching
2
Tooling & Production/Chapter 14
www.toolingandproduction.com
rough, semi-finish, and finish cutting
teeth combined in one tool or string of
tools. A broach tool frequently can
finish machine a rough surface in a
single stroke. A large broach is shown
in Figure 14.2
For exterior surface broaching, the
broach tool may be pulled or pushed
across a workpiece surface, or the sur-
face may move across the tool. Inter-
nal broaching requires a starting hole
or opening in the workpiece so the
broaching tool can be inserted. The
tool or the workpiece is then pushed or
pulled to force the tool through the
starter hole. Almost any irregular

On round tools the diameter of the rear
pilot is slightly less than the diameter
of the finish teeth.
Broach tooth nomenclature and ter-
minology are shown in Figure 14.5a.
Cutting Teeth: Broach teeth are
usually divided into three separate sec-
tions along the length of the tool: the
roughing teeth, semi-finishing teeth,
and finishing teeth (Fig. 14.4). The
first roughing tooth is proportionately
the smallest tooth on the tool. The
subsequent teeth progressively increase
in size up to and including the first
FIGURE 14.2: A large broach is shown (Courtesy Detroit Broach &
Machine Co.)
FIGURE 14.3: A couple of small broached parts are shown. (Courtesy
Detroit Broach & Machine Co.)
Roughing
teeth
Shank length
Length to
first tooth
Cutting teeth
Front pilot
Semifinishing
teeth
Finishing
teeth
Rear pilot

tooth size.
Tooth Pitch: The distance between
teeth, or pitch, is determined by the
length of cut and influenced by type of
workpiece material. A relatively large
pitch may be required for roughing
teeth to accommodate a greater chip
load. Tooth pitch may be smaller on
semi-finishing teeth to reduce the over-
all length of the broach tool. Pitch is
calculated so that preferably, two or
more teeth cut simultaneously. This
prevents the tool from drifting or chat-
tering.
Tooth Gullet: The depth of the
tooth gullet is related to the tooth rise,
pitch, and workpiece material. The
tooth root radius is usually designed so
that chips curl tightly within them-
selves, occupying as little space as
possible. (Fig. 14.5b)
When designing broaches, attention
must also be given to chip load,
chipbreakers, shear angles and side
relief.
Chip Load: As each tooth enters
the workpiece, it cuts a fixed thickness
of material. The fixed chip length and
thickness produced by broaching create
a chip load that is determined by the

ring-shaped chips that would wedge
into the tooth gullets and eventually
cause the tool to break.
Shear Angle: Broach designers
may place broach teeth at a shear angle
to improve surface finish and reduce
tool chatter. When two adjacent sur-
faces are cut simultaneously, the shear
angle is an important factor in moving
chips away from the intersecting cor-
ner to prevent crowding of chips in the
intersection of the cutting teeth.
Another method of placing teeth at a
shear angle on broaches is by using a
herringbone pattern. An advantage of
this design is that it eliminates the
tendency for parts to move sideways in
the workholding fixtures during
broaching.
Side Relief: When broaching slots,
the tool becomes enclosed by the slot
during cutting and must carry the chips
produced through the entire length of
the workpiece. Sides of the broach
teeth will rub the sides of the slot and
cause rapid tool wear unless clearance
is provided. Grinding a single relief
angle on both sides of each tooth does
this. Thus only a small portion of the
tooth near the cutting edge, called the

(b)
FIGURE 14.5: (a)
Broach tooth
nomenclature and
terminology. (b)
Illustration of
how a chip fills
the gullet during
a broaching
operation.
Chap. 14: Broaches & Broaching
4
Tooling & Production/Chapter 14
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volume production they are used in
broaching machines.
Pull broaches (Fig. 14.4) are pulled
either up, down, or horizontally
through or across the workpiece, al-
ways by a machine. Flat or nearly flat
broaches may be pull type, or the
broach may be rigidly mounted, with
the workpiece then pulled across the
broaching teeth. Automobile cylinder
blocks and heads are often faced flat by
this method. Figure 14.6 shows vari-
ous broach configurations both round
and flat types.
Figure 14.1 shows a vertical spline
broaching operation; Figure 14.7

or horns are not required.
Burnishers: Burnishers are broach-
ing tools designed to polish rather than
cut a hole. The total change in diam-
eter produced by a burnishing opera-
tion may be no more than 0.0005 to
0.001 inch. Burnishing tools, used
when surface finish and accuracy are
critical, are relatively short and are
generally designed as push broaches.
Burnishing buttons sometimes are
included behind the finishing tooth
section of a conventional broaching
tool. The burnishing section may be
added as a special attachment or easily
replaced shell. These replacement
shells are commonly used to reduce
tooling costs when high wear or tool
breakage is expected. They are also
used to improve surface finish.
Shell Broaches: Shell broaches can be
used on the roughing, semi-finishing and
finishing sections of a broach tool. The
principal advantage of a shell broach is
that worn sections can be removed and
re-sharpened or replaced, at far less cost
than a conventional single piece tool.
When shells are used for the finishing
teeth of long broaches, the teeth of the
FIGURE 14.6:

from an external surface are commonly
known as surface broaches. Such
broaches are passed over the workpiece
surface to be cut, or the workpiece
passes over the tool on horizontal, ver-
tical, or chain machines to produce flat
or contoured surfaces.
While some surface broaches are of
solid construction, most are of built-up
design, with sections, inserts, or
indexable tool bits that are assembled
end-to-end in a broach holder or sub
holder. The holder fits on the machine
slide and provides rigid alignment and
support. A surface broach assembly is
shown in Figure 14.9a.
Sectional Broaches: Sectional
broaches are used to broach unusual or
difficult shapes, often in a single pass.
The sectional broach may be round or
flat, internal or external. The principle
behind this tool is similar to that of the
shell broach, but straight sections of
teeth are bolted along the long axis of
the broach rather than being mounted
on an arbor. A complex broaching tool
can be built up from a group of fairly
simple tooth sections to produce a cut
of considerable complexity.
Carbide Broach Inserts: Broach-

The type of broach cutting tool re-
quired for a given job is the single most
important factor in determining the
type of broaching machine to be used.
Second in importance is the production
requirement. Taken together, these
factors usually determine the specific
type of machine for the job.
The type of broach tool (internal or
surface) immediately narrows down
the kinds of machines that could be
used. The number of pieces required
per hour, or over the entire production
run, will further narrow the field.
For internal broaching, the length of
a broach in relation to its diameter may
determine whether it must be pulled
rather than pushed through the
workpiece, for a broach tool is stronger
in tension than in compression. This
in turn, helps determine the type of
machine for the job.
The type of drive, hydraulic or elec-
tromechanical, is another important
factor in machine selection. So are
convertibility and automation. Some
machine designs allow for conversion
from internal to surface work. Some
designs are fully automated; others are
limited in scope and operate only with

cell concept (flexible) manufacturing,
where short runs of specialized compo-
(a)
(b)
FIGURE 14.9: (a) A surface broach assembly. (Courtesy Detroit Broach & Machine
Co.) (b) A surface broach assembly with indexable carbide inserts. (Courtesy
Ingersoll Cutting Tools)
Chap. 14: Broaches & Broaching
6
Tooling & Production/Chapter 14
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nents are required. Upon completion
of short runs (1 - 2 years) the machines
can be re-tooled and moved to another
area of the plant without the problem
of what to do with pits in shop floors.
With this type of machine the part sits
on a table that moves up while the
broach is stationary. Stroke lengths
from 30 to 90 inches and capacities
from 5 to 30 tons are the limits for this
machine.
Vertical Internal Pull-up: The
pull-up type, in which the workpiece is
placed below the worktable, was the
first to be introduced. Its principal use
is in broaching round and irregular
shaped holes. Pull-up machines are
now furnished with pulling capacities
of 6 to 50 tons, strokes up to 72 inches,

A special multi-station vertical
broaching machine fixture is shown in
Figure 14.10b.
A vertical broaching machine with
loading and unloading conveyers is
shown in Figure 14.11
14.5.2 Horizontal Broaching
Machines
The favorite configuration for broach-
ing machines seems now to have come
full circle. The original gear or screw
driven machines were designed as
horizontal units. Gradually, the verti-
cal machines evolved as it became
apparent that floor space could be
much more efficiently used with verti-
cal units. Now the horizontal ma-
chine, both hydraulically and mechani-
cally driven, is again finding increas-
ing favor among users because of its
very long strokes and the limitation
that ceiling height places on vertical
machines. About 40 percent of all
broaching machines are now horizon-
tals. For some types of work such as
(b)
(a)
FIGURE 14.10: (a)
A large vertical
broaching machine.

Hydraulically driven horizontal in-
ternal machines are built with pulling
capacities ranging from 2 1/2 to 75
tons, the former representing machines
only about 8 feet long the latter ma-
chines over 35 feet long. Strokes up to
120 inches are available, with cutting
speeds generally limited to less than 40
FPM.
Horizontal Surface Broaching
Machines: This type accounts for only
about 10 percent of existing broaching
machines, but this is not indicative of
the percentage of the total investment
they represent or of the volume of work
they produce. Horizontal surface
broaching machines belong in a class
by themselves in terms of size and
productivity. Only the large continu-
ous horizontal units can match or ex-
ceed them in productivity. Horizontal
surface units are manufactured in both
hydraulically and electro-mechanically
driven models, with the latter now
becoming dominant.
A gear broaching operation is shown
in Figure 14.12b.
The older hydraulically driven hori-
zontal surface machines now are pro-
duced with capacities up to 40 tons,

Chip conveyor
Floor
Broach
Broach backup plate
(b)
FIGURE 14.13: (a) Continuous chain broaching operation. (Courtesy US Broach & Machine Co.) (b) Schematic illustration of a
continuous chain broaching machine.
(a)
Chap. 14: Broaches & Broaching
8
Tooling & Production/Chapter 14
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part tolerances, these machines have
become the largest class of horizontal
surface broaching units built. They are
available with pulling capacities in ex-
cess of 100 tons, strokes up to 30 feet,
and cutting speeds, in some instances,
of over 300 FPM.
14.5.3 Chain Broaching Machines
These have been the most popular type
of machine produced for high-produc-
tion surface broaching. The key to the
productivity of a continuous horizontal
broaching machine is elimination of
the return stroke by mounting the
workpieces, or the tools, on a continu-
ous chain (Fig. 14.13a)
Most frequently, the tools remain sta-
tionary, mounted in a tunnel in the top

signed and manufactured for each ma-
chine to suit the required form and
tolerance of each crankshaft. The
number of inserts and positions of each
segment are designed to give low cut-
ting forces. The roughing segments
have hardened, fixed insert seats and
big chip pockets. Inserts are tangen-
tially mounted and locked in position
by a center screw. A turn-broach cutter
assembly is shown in Figure 14.14b.
Long tool life results due to the short
engagement of the individual cutting
edges. High machine utilization is
obtained because the finishing cutters
need only be changed once per shift
and the roughing cutters about once
every third shift.
FIGURE 14.14: (a)
Turn-broaching
operation of a
crankshaft. (b) Turn-
broach cutter assembly.
(Courtesy Sandvik
Coromant Co.)