Braoching Operation

BROACHING
M Jahanzaib Naqvi
BS Mechanical Technology
UCET
University Of Sargodha

Structure of Presentation
Introduction
Broach
 Different Types of Broaches
Broaching Methods
Broaching Operation
Fixtures used in Broaching
Broaching Machines
Merits and Demerits of Broaching
Machines
Material of Broach

BROACHING
Multipoint cutting tool
Pulled or Pushed through
the surfaces
Internal or External

BROACHING METHODS
Pull Broaching

BROACHING METHODS
Push Broaching

BROACHING METHODS
Surface Broaching

BROACHING METHODS
Continuous Broaching

Fixtures used in Broaching
Broach Centering Fixture
Key Way Broaching Fixture
Horizontal Broaching Fixture

Broach
Broach is a broaching tool, it consists of
a series of distinct cutting edges called
cutting teeth along its length
Feed is accomplished by the increased
step between any two successive teeth
on the broach

 18-4-1 stainless steel
 Carbide
 Cemented Carbide
Material of Broach

Nomenclature of Broach
Front Pilot
This centres the broach in the hole to
be finished just before start of
processing
Roughing Teeth
These are the cutting edges which
remove larger amount of stocks
during cutting. Larger amount
removal generates poor quality of
surface finish but makes the
operation faster

Finishing Teeth
These are cutting edges removing
smaller stocks of material. These
are used for final finishing of the
surfaces and their accurate sizing.
Rear Pilot and Follower Rest
This is a supporting device to the
broach when it is likely to complete
its operation of broaching.

Rear Pilot and Follower Rest
This is a supporting device to the
broach when it is likely to complete
its operation of broaching.
Land
It is the width of flank face of the
broach normally it is kept slightly
inclined to give relief angle to the
flank face of broach.

Pitch
It is the distance between two
corresponding points on two
successive teeth of a broach.
Normally pitch of finishing teeth of a
broach is kept comparatively smaller
than the rough cutting teeth.

Height of the Teeth
Height of the roughing and finishing
teeth gradually increases from the
shank to the finishing teeth. This
increment is called the cut per tooth,
it depends on the material being
machined. Normally the cut per
tooth is taken from 0.01 or 0.2 mm
for the finishing teeth and it may go
up 0.2 mm for the cutting teeth.

DIFFERENT TYPES OF
BROACHES
Progressive Cut Broaches
Broaches have cutting edges
Metal is removed in thick layers by
each tooth from only part of the
work surface
The last tooth of a progressive cut
broach remove a very thin layer
over the entire profile

DIFFERENT TYPES OF
BROACHES
Rotor Cut Broaching
Broaches are used for removing
large amount of material in holes
in forgings or castings
Recommended for making
square holes from a round cost
one

DIFFERENT TYPES OF
BROACHES
Burnishing Broaches
Broaches are used for making
glazed and finished surface on a
steel work piece
Used for finish the hole too

BROACHING MACHINES
According to Working principle
•(a) Hydraulic broaching machine
•(b) Mechanical broaching machine
•(c) Electro-mechanical broaching
machine
•(d) Computer controlled broaching
machine

Hydraulic Broaching Machine
Works with the help
of high pressure fluid
called hydraulic fluid
 The fluid pressure
and its precise
variation provides
motive power to
various components
of the machine

Mechanical Broaching Machine
Power is generated
electrically at its motor
and then it is
transferred to its
various components
like broach holder,
worktable feed
mechanism, etc.
through belt, gears, etc

Electromechanical Broaching
Machine
All the centrals of
process parameters
are controlled with
the help of electronic
control.
 There are
possibilities of
development of
computer controlled
broaching machine.

BROACHING MACHINES
According to Construction
(a) Vertical broaching machine
(b) Horizontal broaching machine
(c) Rotary broaching machine

Vertical Broaching Machine
Movement of
broach is in
vertical direction.
May have the
stroke length more
than 1.5 meter

Horizontal Broaching Machine
Movement of
broach is in
horizontal
direction.
Designed for pull
broaching,
surface
broaching,
continuous
broaching and
rotary broaching.

BROACHING MACHINES
According to Application
(a) internal broaching machine
(b) external broaching machine

Internal Broaching Machine
Broaching of
inner surface of
a round hole,
slot or groove.
Used for
making internal
gears.
Work piece is
clamped into a
special holding
fixture

External Broaching
Surface
broaching
machines
Used to process
external surfaces
of work piece

Major advantages
Of Broaching Machine
 Very high production rate (much higher
than milling, planing, boring etc.)
 High dimensional and form accuracy and
surface finish of the product
Roughing and finishing in single stroke of
the same cutter
Needs only one motion (cutting), so design,
construction, operation and control are
simpler
 Extremely suitable and economic for mass
production

Demerits of Broaching
Machines
Only through holes and surfaces can
be machined
 Usable only for light cuts, i.e. low chip
load and unhard materials
 Cutting speed cannot be high
 Defects or damages in the broach
(cutting edges) severely affect product
quality

Demerits of Broaching
Operation
Design, manufacture and restoration of
the broaches are difficult and
expensive
 Separate broach has to be procured
and used whenever size, shape and
geometry of the job changes
 Economic only when the production
volume is large

Braoching Operation

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