MILLING AND GRINDING
MACHINE
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MILLING
Milling is a metal cutting operation
in which the operating tool is a slow
revolving cutter having a cutting
teeth on its periphery.
Milling cutter is a multipoint cutting
tool.
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MILLING MACHINE
A milling machine is a power operated
machine tool in which the work piece is
mounted on moving table is machined
to various shapes when moved under a
slow revolving cutter.
Work piece is fed against a milling
cutter.
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Metal is removed in the form of
chips by using a rotating multiple
teeth milling cutter.
Milling process is used for producing
flat, contoured or helical surfaces for
toothed gears, slots, etc.
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PRINCIPLE OF MILLING
 The workpiece is mounted on the table can be fed either in the
direction opposite to that of rotating cutter or in the same
direction of the cutter.
 Classification
 Conventional or up milling.
 Climb or down milling.
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UP MILLING
Work piece
advances against
the rotating
cutter.
Chips are
progressively
thicker.
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DOWN MILLING
Work piece is fed
in the same
direction as that of
the cutter tooth.
Cutter enters top of
the work piece and
removes the chip
that gets
progressively
thinner.
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COMPARISON
Up milling
Down milling
 Work piece is fed in
opposite direction of that
of cutter.
 Chips are progressively
thicker.
 Strong clamping is
required since the cutting
force is directed upwards
and tends to lift the work
piece.
 Poor surface finish and
used for hard materials.
 Work piece is fed in same
direction of that of cutter.
 Chips are progressively
thinner.
 Strong clamping is not
required since the cutting
force is directed
downwards and keeps
work piece pressed to
table.
 Good surface finish and
used for soft materials.
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CLASSIFICATION
Milling machine can be broadly classified into :
1. Plain or horizontal type of milling machine
2. Vertical milling machine
3. Universal milling machine
4. Planer type milling machine
5. Profile cutting milling machine
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HORIZONTAL MILLING MACHINE







Base
Column
Arbor
Knee
Saddle
Table
Over arm
YOKE
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 Base – it is a hollow cast iron structure which forms the
foundation of machine on which other parts are mounted.
 Column – houses main drive, transmission system, spindle. It
is provided with vertical guide square or dovetail to
accommodate knee.
 Knee – mounted on vertical slide of column moved up or down
by an elevating screw.
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 Saddle – slides on knee by operating cross feed handle. This
is provided with guide ways on top to support the table.
 Table – mounted on top of saddle with a dovetail fit. Table
slides perpendicular to the axis of saddle movement.
 Arbor – shaft which carries the cutter with its other end
supported by yoke.
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 Over arm – mounted on top of column. Supports the free end
of arbor through yoke.
Working
Work piece is mounted directly on
table using machine vice.
Cutter of required shape and size
are mounted over the arbor which is
driven by spindle.
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 Feed in all 3 axis can be given by using knee elevating handle,
cross slide handle, table movement handle.
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VERTICAL MILLING MACHINE
Base and
column
Spindle
head
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 Base and column – base is the foundation for the machine
and column is the vertical part houses motor, transmission
system.
 Spindle head – mounted on front face of the column at the
top. It has a vertical spindle run by motor to which milling tool
is fitted to end.
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 Working
Work piece is mounted on table and
cutter is mounted on vertical
spindle.
Feed is given by movement of knee,
saddle and table and also vertical
movement of tool.
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MILLING PROCESS







Plain milling
End milling
Slot milling
Angular milling
Form milling
Straddle milling
Gang milling
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PLAIN MILLING
Process used to mill
flat surfaces of the
work piece.
Milling cutter axis is
parallel to the
surface that is being
milled.
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END MILLING
Process of milling
that is used to mill
slots, pockets and
keyways.
Axis of milling cutter
is perpendicular to
the surface of the
work piece.
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SLOT MILLING
Cutter tool – “slot
drill”
Axis of spindle is
horizontal or parallel
to surface of work.
To produce
rectangular slots, Tslots, dovetail slots.
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ANGULAR MILLNG
To produce angular
surfaces like
dovetail, grooves
and chamfers.
Surface is neither
parallel nor
perpendicular to the
milling cutter axis.
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FORM MILLING
This is a process
used to machine
special forms /
contours consisting
of curves.
“form milling cutter”
is the cutting tool
which is shaped
exactly to the
contour to be milled.
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STRADDLE MILLING
Used to machine two
parallel vertical
surfaces at a single
time.
It has two cutters
mounted parallel on
the arbor separated
by a calculated
spacing.
Also used to mill
sides of hexagon.
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GANG MILLING
Similar to straddle
milling but
machining is done
with several types of
milling cutters
according to shape
of desired work.
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