ENM208
MILLING OPERATION
Dr. Mümtaz ERDEM
ANADOLU ÜNİVERSİTESİ
Industrial Engineerng Department
Manufacturing Processes
Milling Operations
Milling is
another basic machining process by which
surface is generated progressively by the removal of chips
from a work piece as it is fed a rotating cutter.
Multiple-tooth cutter is used so that the material removal rate is high.
Good surface finish can be obtained in milling operations.
Milling is particularly well suited and widely used for
mass-production work.
The cutting tool used in milling is known as a Milling Cutter.
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Manufacturing Processes
Milling Classifications
Milling operations can be classified into three categories:
1. Peripheral Milling
2. Face Milling
3. End Milling
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Manufacturing Processes
Face Milling
The generated surface is at right angles to the cutter
axis and is the combined result of actions of the
portions of the teeth located on both periphery and the
face of the cutter.
Most of the cutting is
done by the peripheral
portions of the teeth,
with the face portions
providing some finishing
actions.
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Manufacturing Processes
Peripheral Milling
The surface is generated by teeth located on the
periphery of the cutter body.
The surface generated is
parallel with the axis of
rotation of the cutter
Both
flat
and
formed
surfaces can be produced
by this operation
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Manufacturing Processes
End Milling
The cutter usually rotates on an axis perpendicular
to the workpiece, although it can be tilted to
machine tapered surfaces.
Flat surfaces as well
various profiles can
produced by end milling.
as
be
End milling cutter diameter is
less than the width of the
workpiece.
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Manufacturing Processes
Milling Machines
The milling machine supplies an accurate rotating
spindle for the cutter and a table (vise) to fix and position
the work part. There are two types of machines
Horizontal milling machines:
- Horizontal spindle
-Designed for peripheral milling operations
Vertical milling machines:
- Vertical spindle
- Designed for face and end milling operations
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Manufacturing Processes
Vertical Milling Machine
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Manufacturing Processes
Horizontal Milling Machine
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Manufacturing Processes
Up Milling
Up milling:
Also called conventional milling,
Wheel rotation opposite of the feed.
The chip formed by each cutter tooth
starts out very thin and increases its
thickness.
The length of the chip is relatively longer.
Tool life is relatively shorter.
Need more clamping force to hold the
work part.
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Manufacturing Processes
Down Milling
Down milling:
Also called climb milling,
Wheel rotation is parallel to the feed
The chip formed by each cutter tooth
starts out thick and leaves out thin
The length of the chip is relatively short
Tool life is relatively longer
Need less clamping force to hold the
work part
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Manufacturing Processes
Peripheral Milling Positions
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Manufacturing Processes
Face Milling Positions
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Manufacturing Processes
Milling Calculations
Select Cutting speed, V, and Feed per tooth, ft, from Machining
Data Handbook.
The RPM of the spindle is calculated as
1000V
Ns 
D
Where
Ns = Rotational speed of the spindle (rpm)
V = Surface speed (m/min)
D = the cutter diameter
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Manufacturing Processes
Milling Calculations
The depth of cut, DOC, is simply the distance between the old
and new machined surface (mm).
The width of cut, W, is the width of the cutter or work (mm).
The feed speed, fm, of the table is related to the amount of metal
each tooth removes during a revolution
f m  ft N s n
Where
fm = Table feed speed (mm/min)
ft= feed per tooth (mm/tooth)
n = number of teeth on the cutter (tooth/r)
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Manufacturing Processes
Milling Calculations
The cutting time can be calculated as
For peripheral milling
Where
L  LA
Tm 
fm
Tm = cutting time (min)
L = Length of cut (mm)
LA = Approach length (mm)
LA
2
D D

   DOC   DOC ( D  DOC )
4 2

2
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Manufacturing Processes
Milling Calculations
For Face milling
Where
L  LA  Lo
Tm 
fm
Tm = cutting time (min)
L = Length of cut (mm)
LA = Approach length (mm)
Lo = Overtravel length (mm)
Lo  LA  W ( D  W )
Lo  LA 
D
2
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D
2
D
for W 
2
for W 
Manufacturing Processes
Milling Calculations
The metal removal rate is calculated from
volume L.W .DOC
MRR 

Tm
Tm
Ignoring LA and Lo and substitute for Tm, gives
MRR  f m .W .DOC
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(mm3/min)
Manufacturing Processes
Milling Cutters
The cutting tool used in milling is known as a milling cutter,
the cutting edges called teeth. Types of milling cutters are related
to the milling operations and can be classified as
• Plain milling cutters
• Form milling cutters
• Side milling cutters
• End milling cutters
• Face milling cutters
• Angle mıllıng cutters
• T-slot cutters
• Woodruff keyseat cutters
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Manufacturing Processes
Plain Milling Cutters
Used in peripheral milling operations
- Cylindrical or disk shaped
- Have several straight or helical teeth on periphery
- Used to mill flat surfaces
Plain milling Cutter
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Manufacturing Processes
Form Milling Cutters
Another peripheral milling cutter
- Teeth ground to a special shape to produce a surface
having a desired transverse contour, convex, concave
shape.
Rounding Corner Milling Cutter
Concave milling Cutter
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Convex milling Cutter
Manufacturing Processes
Side Milling Cutters
Similar to plain milling cutters
-Teeth
extend
radial
part
way
across one or both ends of cylinder
toward the center
- Relatively narrow
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Manufacturing Processes
End Milling Cutters
Looks like a drill, but it has teeth on
the end as well as the periphery.
-Have multiple teeth
-Used in milling slots, profiling and
facing narrow surfaces.
- Have either straight or tapered
shanks for smaller and larger cutter
sizes, respectively.
- End mills are also available with
hemispherical ends (ball nose) for
machining curved surfaces.
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Manufacturing Processes
Face Milling Cutters
- Have teeth on periphery and both sides
- Have a center hole so that they
can be arbor mounted.
- Widely used in both horizontal
and vertical spindle machine tools
- Available in a wide variety of
sizes (diameters and heights)
and geometries.
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Manufacturing Processes
Angle Milling Cutters
Angle milling cutters are made in two types:
Single-angle and double angle.
Angle cutters are used for milling slots of
various angles or milling the edges of
workpieces to a desired angle
Single-angle Cutters have teeth on
the
conical surface, usually at an angle of 45 or
60o to the plane face.
Double-angle Cutters have V-shaped teeth,
with both conical surfaces at an angle to the
end faces.
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Manufacturing Processes
T-Slot Cutters
Have teeth on periphery and both
sides
- Used for milling the wide groove of
a T-slot.
- In order to use them, a vertical
groove must first be made with a
slotting mill or an end mill to provide
a clearance for the shank.
- T-slot cutter must be fed carefully,
because it cuts in 5 surfaces
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Manufacturing Processes
Woodruff Keyseat Cutters
Woodruff keyseat cutters are made for
the single purpose of milling the semicylindrical seats required in shafts for
woodruff keys
They
come
in
standard
sizes
corresponding to woodruff key sizes.
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Manufacturing Processes
Shaping Operations
Shaping uses straight line cutting motion with a single point cutting tool to
generate flat surfaces
The workpiece is fed at right angles to the cutting motion between
successive strokes of the tool.
The cutting tool is held in the tool post located in the ram, which
reciprocates over the work with a forward stroke (cutting stroke), and quick
return stroke (non cutting stroke)
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Manufacturing Processes
Shaping Machine (Shaper)
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Manufacturing Processes
Planing Operation
The workpiece is mounted on a table that travels along a straight path.
A horizontal cross-rail, which can be moved vertically along the ways in
the column, is equipped with one or more tool heads.
The cutting tools are attached to the heads, and machining is done along
a straight path.
Planing is usually done on large workpieces – as large as 25 m X 15 m
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Manufacturing Processes
Planing Machine (planer)
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Manufacturing Processes
Shapes produced by shaping and planing operations
In addition to plain flat surfaces, the shapes most commonly
produced on the shaper and planer are shown below
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Manufacturing Processes
Broaching Operation
• Linear Tool Motion (Like
Shaping)
• Single Pass
• Multiple Teeth
• Successive Cutting Steps
• Custom Shaped Geometry
• Need Existing Hole for
Internal Shapes
Broaches are used in
production to finish
holes, splines, and flat
surfaces
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Manufacturing Processes
Abrasive Machining Operations
Abrasive machining is a material-removal process that involves the
interaction of abrasive grains with the workpiece at high cutting speeds and
shallow penetration depths.
In many cases in manufacturing, the surface finish and dimensional
accuracy requirements for a part are too fine, the workpiece material is too
hard, or the workpiece material is too brittle.
One of the best methods for producing such parts is abrasive machining
Abrasive is a small, nonmetallic hard particle having sharp edges and an irregular
shape (unlike the cutting tools described previously). Abrasives are capable or
removing small amounts of material from a surface through a cutting process.
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Manufacturing Processes
Abrasive Machining Operations
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Manufacturing Processes
Surface Grinding Operation
Horizontal spindle
and reciprocating
table grinding
machine
Surface grinding
are used to grind
flat surfaces
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Manufacturing Processes
Surface Grinding Operation
Vertical spindle and
reciprocating table
grinding machine
Surface grinding
are used to grind
flat surfaces
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Manufacturing Processes
External Cylindrical Grinding Operation
Cylindrical Grinding is
commonly
used
for
producing
external
cylindrical surfaces.
The
grinding
wheel
revolves at an ordinary
cutting speed, and the
workpiece rotates on
centers at a much
slower speed.
The grinding wheel and
the workpiece move in
opposite directions at
their point of contact.
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Manufacturing Processes
Internal Cylindrical Grinding Operation
Internal Grinding is
commonly used for
producing
internal
cylindrical
surfaces
(holes).
The grinding wheel
revolves
at
an
ordinary
cutting
speed,
and
the
workpiece rotates on
at a much slower
speed.
The grinding wheel
and the workpiece
move in opposite
directions at their
point of contact.
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Manufacturing Processes
Abrasives
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Manufacturing Processes
Grinding Wheel Identification
Most grinding wheels are identified by a standard marking system that has
been established by the American National Standards Institute (ANSI)
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