Prepared by: Thanks and Regards... Mr. U. ARAVIND, B.E., M.I.S.T.E., LECTURER / MECHANICAL ENGINEERING LAKSHMI AMMAL POLYTECHNIC COLLEGE K.R. NAGAR, KOVILPATTI - 628 503 THOOTHUKUDI DISTRICT, TN Mobile No: 9943244068 Email Id: aravindulaganathanmech@gmail.com aravindmech@lapc.in Milling Machines: Types - column and knee type – plain - universal milling machine - vertical milling machine - principles of operation - specification of milling machines - work holding devices - tool holding devices - arbor - stub arbor - spring collet – adapter. Milling cutters: cylindrical milling cutter - slitting cutter -side milling cutter - angle milling cutter - T-slot milling cutter - woodruff milling cutter - fly cutter - nomenclature of cylindrical milling cutter. Milling operations: straddle milling - gang milling - vertical milling attachment. Indexing plate – differential indexing - simple indexing – compound indexing – simple problems. Generating Process: gear shaper - gear hobbing - principle of operation only. Gear finishing processes: burnishing – shaving - grinding and lapping - gear materials.

1. 1
Lakshmi Ammal Polytechnic College
Department of Mechanical Engineering
Subject Name : Special Machines
Subject Code : 32042
Year & Semester : II / IV
Scheme : M
U. Aravind
Lecturer/Mech
LAPC
K.R. Nagar

2. UNIT – 3
MILLING MACHINES & GEAR
GENERATING PROCESS
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4. • Milling is the process of removing
metal by a rotating multipoint
cutter called as Milling Cutter
• The machine used for milling
process is called Milling machine
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5. TYPES OF MILLING PROCESS
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6. Up Milling
• It is also called conventional
milling.
• Metal is removed when the cutter
teeth move upwards.
• The cutter rotates opposite to the
direction of feed of work piece.
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7. Down Milling
• It is also called climb milling.
• Metal is removed when the cutter
teeth move downwards.
• The cutter rotates same direction as
the feed for work piece.
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8. TYPES OF MILLING
MACHINE
I. Column and knee type.
i. Plain/Horizontal milling
machine.
ii. Vertical milling machine.
iii. Universal milling machine.
iv. Omniversal milling machine
II. Plano miller
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9. III. Fixed bed type milling
machine
IV) Special type
i. Rotary table milling machine.
ii. Drum type milling machine.
iii. Planetary milling machine.
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•Plain milling machine is
also known as horizontal
milling machine
•The spindle of the
machine is horizontal.

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Machine Movements:
•Knee - Vertical Up and Down
movement
•Saddle - Crosswise
movement
•Table - Longitudinal
movement

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•The spindle of the machine is
Vertical.
•This machine is used for machining
grooves, slots and flat surfaces.
•End milling cutters and face
milling cutters are generally used
in vertical milling machine.

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Machine Movements:
•Vertical Up and Down movement
- Knee
•Crosswise movement - Saddle
•Longitudinal movement - Table
•Angular Movement - Spindle
Head Swivel Base

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•It is used to produce spur
gear, helical gear, bevel
gear, twist drill and
reamers.

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Machine Movements:
•Vertical Up and Down movement
- Knee
•Crosswise movement - Saddle
•Longitudinal movement - Table
•Angular Movement - Table
Swivel Base (45º)

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•The table length and width
•Maximum longitudinal, cross
and vertical travel of the Table
•Number of spindle speeds and
feeds
•Floor space and net weight
•Spindle nose taper size
•Type

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•Plain vice.
•Swivel vice.
•Universal vice.
•Indexing head.
•Milling fixture.

38. Plain Vice
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39. Plain Vice
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40. Swivel Vice
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41. Swivel Vice
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42. Universal Vice
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43. Indexing head
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44. Indexing head
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45. Milling Fixture
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1. Arbors
(a)Standard arbor
(b)Stub arbor
2. Adapters
3. Spring collets

48. Standard Arbor
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49. Standard Arbor
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50. Stub Arbor
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51. Stub Arbor
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52. Adapter
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53. Adapter
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54. Spring Collet
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55. Spring Collet
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57. Cylindrical Milling Cutter
or Plain Milling Cutter
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58. Cylindrical Milling Cutter or Plain
Milling Cutter
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•Roughing cutters
will have less
number of teeth.
•Finishing cutters
will have more
number of teeth

59. Slab Milling Cutter
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60. Slab Milling Cutter
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•Cutter having a
width more than
its diameter.

61. Slitting Saw
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62. Slitting Saw
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•The cutter is
very thin.
• Its width varies
from 0.8 to
5mm.

63. Side Milling Cutter
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64. Side Milling Cutter
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•Side milling
cutter has
cutting edges on
its periphery
and also on the
sides.

65. Angle Milling Cutter
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66. Angle Milling Cutter
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•Angle milling
cutters are used for
producing angular
surfaces
•Two types
a. Single Angle
milling cutter
b. Double Angle
milling cutter

67. End Milling Cutter
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68. End Milling Cutter
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69. End Milling Cutter
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•Tapered shank
cutters are fitted to
the spindle using
adapters.
•Straight shank
cutters are fitted to
the spindle using
collets

70. T-Slot Milling Cutter
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71. T-Slot Milling Cutter
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•It is used of producing T-slots

72. Woodruff Key Cutter
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73. Woodruff key cutter
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•This cutter is used for cutting woodruff
key slots on shafts.

74. Fly Cutter
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75. Fly Cutter
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•It is used in milling machine when
standard cutters are not available.
•The cutter removes metal when it
rotates.

76. Convex Form Milling cutter
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77. Concave Form Milling cutter
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1. Plain milling
2. Form milling
3. Face milling
4. Side milling
5. End milling
6. T-slot milling
7. Straddle milling
8. Gang milling

82. Plain Milling
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•It is used to
producing flat,
horizontal surface.
•A cylindrical
milling cutter is
used here .

83. Plain Milling
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84. Form Milling
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•It is used to
producing the
required profiles on
the work piece.
• A form milling
cutter is used

85. Face Milling
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•It is used to machining flat
surface of the face of the
workpiece the required profiles
on the work piece.
• A face milling cutter is used

86. Face Milling
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87. Side Milling
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•A Side milling
cutter is used for
milling the
vertical side of the
work piece

88. End Milling
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•End milling is the operation
of producing narrow slots,
grooves and key ways using
end mills.
•The slots produced may be
vertical or horizontal

89. End Milling
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90. T slot Milling
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•A T-slot is
produced by
using a T-slot
cutter

91. T slot Milling
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92. Straddle Milling
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•It is the operation of machining
two vertical surfaces of the work
piece at a time
•Two side milling cutters are used
•It is used for milling square and
hexagonal surfaces

93. Straddle Milling
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94. Straddle Milling
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95. Gang Milling
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•Gang milling is the operation of
milling several surfaces of the
work pieces at a time
•Gang milling operation is used in
mass production
•Three or more milling cutters
used

96. Gang Milling
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97. Gang Milling
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•Vertical milling attachment is used
for doing vertical milling operations
on a horizontal milling machine.
•End milling cutter is held to the
vertical spindle of the attachment.
•By using this attachment grooving,
T-slot milling and face milling
operations can be done

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103. • Indexing is the process of evenly
dividing the circumference of a
circular work piece into equally
spaced divisions.
• It is used in cutting gear teeth,
cutting splines, milling grooves in
reamers
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105. • Indexing is accomplished using a
special attachment known as
dividing head or index head
• It contains an indexing
mechanism which is used to
control the rotation of the index
head spindle to space or divide a
work piece accurately.
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107. Types of dividing heads
Plain / Simple indexing
head
Universal indexing head
Optical indexing head
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108. Plain / Simple indexing head
•A plain dividing head has a
fixed spindle axis and the
spindle rotates only about a
horizontal axis.
•It is used for simple
indexing
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110. Universal indexing head
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111. Universal Dividing head:
• It is used As a work holding device
(horizontal, vertical or inclined at angle to
the table or cutter)
• For Indexing the workpiece
• To rotate the workpiece through a desired
angle
• It can divide the blank into more number of
divisions than that is possible in plain
dividing head.
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118. • The indexing plate is a circular plate with
a series of six or more circles of equally
spaced holes.
• It helps to accomplish indexing (dividing)
of the work into equal divisions. It is a
circular plate approximately 6 mm thick,
with holes (equally spaced) arranged in
concentric circles.
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119. • The space between two subsequent
holes is same for each circle;
however, it is different for different
circles.
• For a plain dividing head, the index
plate is fixed to the body of the
dividing head
• For a universal dividing head it is
mounted on the sleeve of the worm
shaft.
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120. Various manufactures in
produced index plates with
different number of hole
circles.
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121. I. Brown and Sharpe milling
machines are:
•Plate No. 1 - 15, 16, 17, 18, 19,
20
•Plate No. 2 - 21, 23, 27, 29, 31,
33
•Plate No. 3 - 37, 39, 41, 43, 47,
49
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122. II. Cincinnati and Parkinson
milling machine
•Obverse (A) - 24, 25, 28,
30, 34, 37, 38, 39, 41, 42,
43
•Reverse (B) - 46, 47, 49,
51, 53, 54, 57, 58, 59, 62,
and 66
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123. III. Index plates made in
Germany are:
• Plate No. 1 - 23, 25, 28, 31,
39, 43, 51, 59
• Plate No. 2 - 16, 27, 30, 33,
41, 47, 53, 61
• Plate No. 3 - 22, 24, 29, 36,
37, 49, 57, 63
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124. IV. Cincinnati Milling Machine
Co. U.S.A.
• Plate No. 1
Obverse (A) - 30, 48, 69, 91, 99, 117, 129,
147, 171, 177, 189
Reverse (B) - 36, 67, 81, 97, 111, 127, 141,
157, 169, 183, and 194
• Plate No. 2
Obverse (A) - 34, 46, 79, 93, 109, 123, 139,
153, 167, 181, 197
Reverse (B) - 32, 44, 77, 89, 107, 121, 137,
151, 163, 179, and 193
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125. • Plate No. 3
Obverse (A) - 26, 42, 73, 87, 103, 119, 133,
149, 161, 175, 191
Reverse (B) - 28, 38, 71, 83, 101, 113, 131,
143, 159, 173, and 187
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135. • Direct Indexing (Rapid
Indexing) is the simplest form of
indexing. Used for quick
indexing of workpiece.
• The number of divisions required
by direct indexing is limited by
the number of holes/slots in the
direct indexing plate.
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136. •Direct indexing plates are
available with 24, 30 and
36 holes or slots.
•It is possible to index any
number of divisions which
is a factor of total
holes/slots in the plate
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137. Slots Direct indexing
division
• 24 2 3 4 6 8 12 24
• 30 2 3 5 6 10 15 30
• 36 2 3 4 6 9 12 18 36
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138. • To perform this type of indexing,
the worm shaft must be
disengaged from the worm gear
wheel.
• Whenever starting to machine the
first hole, it is necessary to make
sure that the indexing pin is in the
hole or slot No. Zero or 24 of the
indexing plate.
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140. Direct Indexing:
No. of holes or slots to be moved,
Where, N is the No. of divisions required
I = 24/N
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141. Direct indexing: Example
• What is the index movement required to mill 8
slots on a workpiece?
Solution:
Given Data:
No of Divisions required , N = 8
To Find:
No of Holes or Slots to be moved
We know I = 24/N
I = 24/8 = 3 i.e I = 3
3 slots to be moved for each side
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142. 26 April 2021 142
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143. • Work positioned by means of
crank, index plate, and sector
arms
• Worm attached to crank must be
engaged with worm wheel on
dividing head spindle
• 40 teeth on worm wheel
• One complete turn on index
crank cause spindle and work to
rotate one-fortieth of a turn (ratio
40:1)
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144. Simple Indexing:
Index Crank movement
Where, N is the No. of divisions required
I = 40 /N
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145. Simple indexing: Example
1.Indexing required to cut 8
divisions
We know,
I = 40/8 = 5
Answer:
5 full turns of the index
crank
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146. 2.Indexing required to cut 7 divisions
We know I = 40/7 = 5 5/7
Finishing Indexing for Seven Flutes
• Index-plate hole circles
A. Brown & Sharpe
• Plate 1 15-16-17-18-19-20
• Plate 2 21-23-27-29-31-33
• Plate 3 37-39-41-43-47-49
B. Cincinnati Standard Plate
• One side 24-25-28-30-34-37-38-39-41-42-43
• Other side 46-47-49-51-53-54-57-58-59-62-66
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147. Choose any hole circle that is divisible by
denominator 7
• If we choose Plate no. 2
5/7 = 15/21
I = 5 15/21
So, 5 full turns plus 15 holes on 21 hole
circle
• If we choose Plate no. 3
5/7 = 35/49
I = 5 15/21
So, 5 full turns plus 35 holes on 49 hole
circle
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149. • This method is used for divisions that could
not be indexed by simple indexing
• The required division is obtained by
combination of:
Movement of the index crank similar to
simple indexing
Simultaneous movement of the index plate
when the crank is turned
• The rotation of the index plate may be in the
same direction or opposite to the crank
rotation
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151. Rule for
Differential
Indexing
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152. •The change gears
supplied with the
dividing head are as
follows:
22, 24, 28, 32, 40, 44, 48,
56, 64, 72, 86,100
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153. I. Index Crank
Movement for
each division,
I = 40/A
A= Approximate number
of divisions
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154. II. Gear Ratio = Driving
gear/Driven gear
(= Gear on the
spindle/Gear on the bevel
gear shaft)
G = (A-N) × 40/A
where:
• N = The required number of divisions
to be indexed
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155. III. Number of idlers in
the change gears
• If (A-N) is positive, the index
plate must rotate in the same
direction as the crank
• If (A-N) is negative, the index
plate must rotate in the opposite
direction to the crank
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156. • Gear
A-N SIMPLE
GEAR
TRAIN
COMPOUND
GEAR TRAIN
Positive One
idler
No idler
Negative Two
idlers
One idler
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157. RESULT:
For indexing N divisions, a 40-tooth gear
is mounted on the dividing head spindle
and A - tooth gear is mounted on the
worm shaft.
Plate rotation is ----- and -----idlers are
used.
After proper gears installed, the simple
indexing for A divisions should be
followed.
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158. Simple change gears
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159. Compound change gears
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160. Differential indexing: Example
1.Calculate the indexing and
change gears required for 83
divisions.
The change gears supplied with
the dividing head are as follows:
24, 24, 28, 32, 40, 44, 48, 56, 64,
72, 86, 100
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161. •The available index plate
hole circles are as follows:
•Plate 1: 15, 16, 17, 18, 19, 20
•Plate 2: 21, 23, 27, 29, 31, 33
•Plate 3: 37, 39, 41, 43, 47, 49
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162. Solution:
•Given Division, N =
83
•Approximate
Division, A = 86
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163. Step 1: Index Crank
Movement for each division
•We know I = 40/A =
40/86
I= 20/43
•Use Plate No 3 on 43
hole circle
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164. Step 2: Gear Ratio
We Know
Gear Ratio = Driving
gear/Driven gear
(= Gear on the
spindle/Gear on the bevel
gear shaft)
G = (A-N) × 40/A
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165. 86
40
x
83)
-
(86
ratio
Gear 
43
60
43
20
3
86
40
x
(3)
ratio
Gear 



A
40
x
N)
-
(A
ratio
Gear 
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166. Change Gears =
Gear on the
spindle/Gear on the
bevel gear shaft =
60/43
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167. Step 3: Number of idlers
in the change gears
In this problem, A-N value is
Positive, so Simple Gearing is to
be used, So Index Crank rotate
in Clockwise Direction(Same
Direction) of Crank & one idlers
must be used
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168. RESULT:
For indexing 83 divisions, a 40-
tooth gear is mounted on the dividing
head spindle and 86 - tooth gear is
mounted on the worm shaft.
Plate rotation is Clockwise and One
idlers are used.
After proper gears installed, the
simple indexing for 86 divisions
should be followed.
26 April 2021 168
U.Aravind, Lect/Mech

169. 26 April 2021 169
U.Aravind, Lect/Mech