Shaper – Types of operations. Drilling, reaming, boring, Tapping. Milling operations-types of milling cutter. Gear cutting – forming and generation principle and construction of gear milling ,hobbing and gear shaping processes –finishing of gears.
3. UNIT III - Syllabus
Shaper – Types of operations. Drilling,
reaming, boring, Tapping. Milling operations-
types of milling cutter. Gear cutting – forming
and generation principle and construction of
gear milling ,hobbing and gear shaping
processes –finishing of gears.
5. Shaper
A shaper is reciprocating type of machine tool
with single point cutting tool is used to
produce flat surfaces.
The flat surface may be horizontal, vertical or
inclined. It has the three important parts such
as table, tool head and ram. (upto 1000 mm
long).
9. Types of Shapers
• According to the type of driving mechanism
a) Crank drive type
b) Whit worth driving mechanism type
c) Hydraulic drive type
• According to the position of ram
a) Horizontal shaper
b) Vertical shaper
10. • According to the table design
a) Standard or plain shaper
b) Universal shaper
• According to the type of cutting stroke
a) Push out type
b) Draw cut type
11. Main parts of a shapers
• Base
• Column
• Cross rail
• Table
• Ram
• Tool head
13. Shaper Specifications
• Type of drive (Mechanical or Hydraulic)
• Power of motor
• Speed and feed available
• Ratio of cutting time and return stroke time
• Floor area required
• Net weight
14. Quick Return Mechanism
To convert the rotary motion of a motor into
reciprocating motion of the tool, various
types of drives are provided in the shaper
because the metal is removed during forward
stroke. But no metal is cut during return
stroke.
Due to this the time taken for the return stroke
should be reduced by making the return
stroke faster than the cutting stroke.
20. Advantages of Hydraulic Drive
• Uniform cutting speed
• Smooth and noiseless operation
• Changing of cutting speed is easier
• Higher ratios on quick return can be
obtained
• More safety as the relief valve is provided
22. Crank and slotted link mechanism
The crank and slotted quick
return mechanism converts rotatory motion
into linear motion. It is extensively used in
shaping and cutting machines and is
particularly useful in cutting flat surfaces out
of metal stock. The return stroke of the ram is
faster than the advancing stroke.
23. When the bull gear rotates, the sliding block also
rotates in the crank pin circle. This
arrangement provides a rocking movement to
the rocker arm. As the top of the slotted link is
connected to the ram, the ram reciprocates
horizontally. So, bull gear rotation is converted
into the reciprocating movement of the ram.
26. Whitworth quick return mechanism
The Whitworth quick return mechanism converts
rotary motion into reciprocating motion, but unlike
the crank and slider, the forward
reciprocating motion is slower rate than
the return stroke
30. A shaper is mostly used to machine a flat, true
surface on a workpiece. Horizontal surfaces
are machined by moving the work mounted
on the machine table at a cross direction
with respect to the ram movement. The
clapper box can be set vertical or slightly
inclined towards the uncut surface. This
arrangement enables the tool to lift
automatically during the return stroke. The
tool will not drag on the machined surface
33. • A vertical cut is made while machining the
end of a workpiece, squaring up a block or
machining a shoulder.
• The feed is given to the tool by rotating the
down feed screw of the vertical slide. The
table is not moved vertically for this
purpose. The apron is swivelled away from
the vertical surface being machined
35. • If the surface to be machined is neither
horizontal nor perpendicular, the surface is
called inclined surface. Machining ‘V’
grooves and dovetail grooves are some
examples for angular machining.
• Machining the inclined (angular) surfaces
can be done in several ways.
44. DRILLING
• Creates a round hole in a work part
• Contrasts with boring which can only enlarge
an existing hole
• Drilling is the process of producing the hole on
the workpiece by using a rotating cutter called
Drill. The machine on which the drilling is
carried out is called Drilling Machine (Drill
Press).
45. Classification of Drilling Machine
• Portable Drilling Machine
• Sensitive Drilling Machine
• Upright Drilling Machine
– Round Column type or Pillar type
– Square section type
• Radial Drilling Machine
• Gang Drilling Machine
• Multiple Spindle Drilling Machine
• Automatic Drilling Machine
• Deep Hole Drilling Machine
46. Portable Drilling Machine
Portable drilling machine can be carried and
used anywhere in the workshop.
These machines can accommodate drills from
12mm to 18 mm diameter. Portable drilling
machines are operated at higher speeds.
47. Sensitive Drilling Machine
It is designed for drilling small holes at high
speeds in light jobs. High speed and hand
feed are necessary for drilling small holes.
The base of the machine is mounted either on
a bench or on the floor by means of bolts and
nuts. It can handle drills upto 15.5mm of
diameter. The drill is fed into the work purely
by hand . The operator can sense the progress
of the drill into the work because of hand
feed.
49. Upright Drilling Machine
The upright drilling machine is designed for
handling medium sized workpieces. Though it
looks like a sensitive drilling machine, it is
larger and heavier than a sensitive drilling
machine.
Holes of diameter upto 50mm can be made with
this type of machine. Besides, it is supplied
with power feed arrangement. For drilling
different types of work, the machine is
provided with a number of spindle speeds and
feed.
51. Radial Drilling Machine
The radial drilling machine is intended for drilling on
medium to large and heavy workpieces. It has a
heavy round column mounted on a large base. The
column supports a radial arm, which can be raised or
lowered to enable the table to accommodate
workpieces of different heights.
The arm, which has the drill head on it, can be swung
around to any position. The drill head can be made to
slide on the radial arm. The machine is named so
because of this reason. It consists of parts like base,
column, radial arm, drill head and driving
mechanism.
53. Gang Drilling Machine
• Gang drilling machine has a long common
table and a base. Four to six drill heads are
placed side by side. The drill heads have
separate driving motors. This machine is used
for production work.
• A series of operations like drilling, reaming,
counter boring and tapping may be
performed on the work by simply shifting the
work from one position to the other on the
work table. Each spindle is set with different
tools for different operations.
56. Multiple Spindle Drilling Machine
This special purpose drill press
has many spindles connected
to one main work head.
All of the spindles are fed into
the workpiece at the same
time. This type of drilling
machine is especially useful
when you have a large
number of parts with many
holes located close together.
58. Deep Hole Drilling Machine
A special machine and drills are required to drill
deeper holes in barrels of gun, spindles and
connecting rods. The machine designed for this
purpose is known as deep hole drilling machine.
High cutting speeds and less feed are necessary
to drill deep holes.
A non- rotating drill is fed slowly into the rotating
work at high speeds. Coolant should be used
while drilling in this machine. There are two
different types of deep hole drilling machines
• Vertical type
• Horizontal type
63. Operations of Drilling Machine
• Reaming:
Used to slightly enlarge a hole, provide better tolerance
on diameter, and improve surface finish.
The size of hole made by drilling may not be accurate
and the internal surface will not be smooth.
Reaming is an accurate way of sizing and finishing a
hole which has been previously drilled by a multi point
cutting tool known as reamer.
The speed of the spindle is made half that of drilling.
Reaming removes very small amount of metal ( approx
0.375 mm).
67. • Boring:
It is an operation of enlarging a hole by a single
point cutting tool . Boring is done where the
suitable size drill is not available. If the hole size
is very large, it can not be drilled. Boring corrects
out roundness of a hole. Boring is a slow process.
68. • Counter boring
Counter boring is the operation of enlarging the
end of the hole cylindrically. The enlarged hole
forms a square shoulder with the original hole.
This is necessary in some cases to
accommodate the heads of bolts, studs and pins.
The tool used for counter boring is known as
counter bore.
The cutting speed for counter boring is atleast
25% lesser than that of drilling.
70. • Counter sinking
Countersinking is the operation of making a
cone shaped enlargement at the end of the hole.
The included angle of the conical surface may be
in the range of 60° to 90°. It is used to provide
recess for a flat headed screw or a counter sunk
rivet fitted into the hole. The tool used for
counter sinking is known as a countersink. It has
multiple cutting edges on its conical surface. The
cutting speed for countersinking is 25% lesser
than that of drilling.
72. • Tapping
Tapping is the operation of cutting internal
threads by means of a cutting tool called ‘tap’.
Tapping in a drilling machine may be performed
by hand or by power. When the tap is screwed
into the hole, it removes metal and cuts internal
threads which will fit into external threads of
the same size.
74. • Spot Facing
Spot facing is the operation of smoothing and
squaring the surface around a hole. It is done
to provide proper seating for a nut or the head
of a screw.
75. • Trepanning:
Trepanning is the operation of producing a hole
in sheet metal by removing metal along the
circumference of a hollow cutting tool.
Trepanning operation is performed for
producing large holes. Fewer chips are
removed and much of the material is saved
while the hole is produced. The tool may be
operated at higher speeds.
77. Milling
Milling is a metal removing process by a multipoint
cutter. The metal is removed by feeding the work
against the rotating cutter.
Principle:
The workpiece is holding on the worktable of the
machine. The table movement controls the feed of
workpiece against the rotating cutter. The cutter
is mounted on a spindle and revolves at high
speed. Except for rotation the cutter has no other
motion. The cutter teeth remove the metal from
the surface of workpiece and the desired shape is
produced.
80. Specifications of Milling Machine
• Table length and width
• Maximum longitudinal cross and vertical
travel of the table
• Number of spindle speeds and feeds
• Power of driving motor
• Standard Taper hole size of the spindle
• Net weight of the machine
81. Types of milling machines
• Column and knee type
a) Plain or Horizontal milling machine
b) Vertical milling machine
c) Universal milling machine
• Bed Type Milling Machine
–Simplex Milling Machine
–Duplex Milling Machine
–Triplex Milling Machine
• Plano – Type Milling Machine
• Special Type Milling Machine
–Rotary table Milling Machine
–Drum Milling Machine
–Profile Milling Machine
91. Plain or Slab Milling:
It is a method of producing a plain, flat,
horizontal surface parallel to the axis of
rotation of the cutter.
Face Milling:
It is a method of producing a flat surface at
right angles to the axis of the cutter.
94. Side Milling
It is the operation of production of a flat vertical
surface on the side of a work-piece by using a
side milling cutter.
95. Angular Milling
It is a method of producing a flat surface making
an angle to the axis of the cutter.
The cutter used may be a single or double angle
cutter depending upon whether a single
surface is to be machined or two mutually
inclined surfaces simultaneously.
96. Gang Milling
It is a method of milling by means of two or more
cutters simultaneously having same or
different diameters mounted on the arbor of
the milling machine.
98. Form Milling
Form milling is the operation of producing
irregular surfaces or contours by using
required form cutters. The irregular shape
may be convex, concave or any other shape.
99. End Milling
It is the operation of producing both peripheral
and face milling operation simultaneously
generates vertical, horizontal or angular
surfaces by using a end milling cutter. It is
used for milling slots, grooves, keyway etc.
100. Saw Milling
It is a method of producing deep slots and
cutting materials into the required length
by slitting saws.
101. T slot Milling
Milling of T-slots is produced in two or three
stages. In the first operation, the end milling
operation or a plain slot is made by using an
end milling cutter.
102. Straddle Milling
Straddle Milling operation is the production of
two vertical flat surfaces on both sides of the
job by using two side milling cutters which are
separated by collars. It is used for milling
square and hexagonal surfaces.
103. Gear Cutting Milling
The gear cutting operation involves cutting of
different types of gears on a milling machine.
Spur ,helical gears are cut on milling machine
with help of indexing mechanism .
104. TYPES OF MILLING CUTTERS
• Plain or Slab milling cutter
• Side milling cutter
• Metal slitting saw
• Angle milling cutter
• End mill cutter
• T-slot milling cutter
• Fly cutter
• Form cutter
105.
106. Plain Milling cutter
Its cylindrical shaped cutter having teeth on its
circumference. It is used to machine the flat
surface parallel to its axis.
107. Slab Milling cutter
The plain milling cutters having the width more
than its diameter is called slab mill cutter. Its
used for rough machining with coarse feed. The
cutter has less number of teeth.
108. Side Milling cutter
It has cutting edges on its periphery and also
on sides. This cutter is used for removing
metal from the side of the workpiece. It also
used for cutting slots.
109. End Mill cutter
It have cutting teeth on the end as well as on the
periphery of the cutter. The peripheral teeth
may be straight or helical. Its similar to a drill or
reamer.
110. Metal slitting saw
These are very thin cutters in varying thickness
from 0.5mm to 5mm. Its used for cutting deep
slots and parting off materials into pieces.
111. Angle Milling cutter
All cutters which have their cutting teeth at an
angle to the axis of rotation are called Angular
cutters. Its used for milling V grooves, notches,
Dovetail slots, reamer teeth and other angular
surfaces.
112. T-Slot Milling cutter
The arrangement of cutting teeth is similar to a
side milling cutter. But this cutter has a tapered
shank. It has cutting edges on its periphery and
sides.
113. Form Milling Cutter
The cutters which are designed to cut definite
shapes are known as Form milling cutters.
Shapes are convex or concave cutters, gear
cutters, flute cutters and corner rounding
cutters.
114. Fly cutter
Its actually a single point tool which is used in
milling machine when standard cutters are
not available. Its mounted on arbor. The cutter
removes metal when it rotates.
115. Woodruff key slot Milling cutter
It’s a small type of end milling cutter which is
similar to plain and side mills. The sides of the
cutters are ground concave. It provides a
clearance for the cutter movement. Its used to
cut woodruff key slot in a shaft.
116. Indexing or Dividing Heads
Indexing is the process of dividing the
periphery of a job into equal number of
divisions. For doing this indexing, an
attachment known as Dividing Head is used in
the milling machine.
Types of Dividing Heads:
1. Plain or simple dividing head
2. Universal dividing head
3. Optical dividing head
119. 1. Plain or simple dividing head
This type of dividing head is hand operated and it
is used for simple indexing. It has a cylindrical
spindle. The hand wheel directly rotates the
spindle. The index plate is circular plate having
24 or 12 slots which are equally spaced on the
periphery.
On the plain dividing head there is simply a fixed
horizontal spindle that is rotated using a worm
mechanism.
122. 2. Universal dividing head
Its very useful device for purpose of indexing work.
The worm drive is enclosed in a strong body. The
driving mechanism consists of a worm drive, index
plate, sector arms, change gears and spindle.
It consists of a 40-tooth worm wheel fastened to the
work spindle, a single-cut worm, a crank for
turning the worm shaft, and an index plate and
sector. since there are 50 teeth in the worm wheel,
one turn of the index crank causes the worm wheel
and consequently the spindle to make 1/40 of a
turn; so 40 turns of the index crank revolve the
spindle one full turn.
123.
124.
125. Type 1 has 3 plates of 6 circles each, drilled as follows:
Plate 1 - 15, 16, 17, 18, 19, 20 holes.
Plate 2 - 21, 23, 27, 29, 31, 33 holes.
Plate 3 - 37, 39, 41, 43, 47, 49 holes.
Type 2 has one plate drilled on both sides with circles
divides as follows;
First side - 24, 25,28, 30, 34, 37, 38, 39, 41, 42, 43
holes.
Second side - 46, 47, 49, 51, 53, 54, 57, 58, 59, 62, 66
holes.
126. Gear Cutting or Gear Forming Methods
• Gear cutting by single point form tool
• Gear milling using a formed end mill
• Gear cutting by shear speed shaping
process
• Gear broaching
127. Gear cutting by single point form tool
A single point cutting tool is used for cutting
the gear in a shaping or planning machine.
The cutting edge of the tool is made to the
shape of the gear tooth.
128. Gear milling using a formed end mill
In this type the cutting edges are formed to
the shape of the gear tooth space. The form
end mill cutter is held on the spindle of
vertical milling machine.
129. Gear cutting by shear speed shaping
process
In this type, the form tools are radially arranged in the
cutter head. The number of form tools is equal to the
number of teeth required on the blank. So all the
spaces are cut at the same time by feeding along with
tools towards the centre of blank during cutting
stroke.
130. Gear Broaching
This method is mainly used for making internal gears
with an accurate shape. It has a number of cutting
edges equal to the number of teeth required on the
gear blank. Even very small gear can be cut in a single
stroke of the broaching tool.
131.
132.
133. Gear generation Processes or Methods
• Gear shaping process
• Gear planning process
• Gear hobbing process
134. Gear shaping process
Gear shaping is one of the generation methods
used for cutting cylindrical gears. Gear shaping
is done on a special type of machine called
Gear shaper.
135.
136.
137. Various movements obtained from gear shaper:
• Rotary motion of the cutter and blank
• Radial feed of the cutter towards the blank
• Vertical reciprocating motion of the cutter
• Withdrawal motion of the blank away from
the cutter during return stroke.
Applications:
• Internal and External spur gears
• Helical gears (Using special attachments)
139. A straight line generator produces an involute
curve when a blank is rolled without slip
relative to the generator. Its also called Rack
cutter generating process. The gear blank is
mounted on the planing machine. It may be
fitted either horizantally or vertically on the
table.
142. The process of generating a gear by means of a
multipoint rotating cutter called Hub is known
as Hobbing. The hob has helical threads. The
motion of both gear blank and hob are
maintained continuously and steady. One
rotation of hub makes one tooth on the gear
blank.
145. Gear Hob
• Hobbing is used for generating spur, Helical and
Worm Gears.
146. Finishing of Gears
• Gear Shaving
• Roll finishing of Gear Tooth
• Gear Burnishing
• Gear Grinding
• Gear Lapping
• Gear Honing
147. Gear Shaving
Gear shaving is a free cutting gear finishing
operation which removes small amounts of
metal from the working surfaces of gear teeth.
Its purpose is to correct errors in index, helix
angle, tooth profile and eccentricity.
148.
149. Roll finishing of Gear Tooth
This process involves use of two hardened
rolling dies containing very accurate tooth
profile of the gear to be finished. The gear to
be finished is held between the two dies.
150. The material of the die is very hard as compare
to the material of gear so there is a plastic
deformation of high points and burrs on the
profile of gear tooth resulting to smooth
surface.
151.
152. Gear Burnishing
Gear Burnishing is another method of surface
finishing for gear teeth of a gear which is done
before heat treatment. It consists of rolling the
work gear with the hardened rotating gears
called Burnishing Gears whose teeth are very
hard, smooth and accurate.
153.
154. Gear Grinding
The abrasive grinding wheel of a required shape and
geometry is used to finish the gear teeth. Gear to be
finished is mounted and reciprocated under the
grinding wheel. Each of the gear teeth is subjected to
grinding operations this way.
155.
156. Gear Lapping
The process of lapping is used to improve
surface finish of already made teeth. In this
process the gear to be lapped is run under load
in mesh with cast iron toothed laps. Abrasive
paste is introduced between the teeth. It is
mixed with oil and made to flow through the
teeth. One of the mating members (either gear
or lapping tool) is reciprocated axially along
with the revaluations.
157. Gear lapping is the process of imparting a very fine
finish and high degree of accuracy to gear teeth, by
using a lapping tool and applying a fine-grained
abrasive between a work material and a closely fitting
surface, called a lapping plate. By running mating pairs
together in a gear lapping machine and feeding a liquid
abrasive compound under pressure into the gear pair,
small amounts of metal are removed as the gears rotate,
thus refining the tooth surface and achieving the
desired contact pattern.
158. Gear Honing
Honing is an abrasive machining process that
produces a precision surface on a metal
workpiece by scrubbing an abrasive stone
against it along a controlled path. Honing is
primarily used to improve the geometric form of
a surface, but may also improve the surface
texture.
159. Improving the quality of spur and helical gears is
critical in production, and there are many
methods to accomplish that. Rotary gear shaving
and roll-finishing are done in the green or soft
state prior to heat treatment.
Gear Honing processes have the ability to modify
the gear geometry in order to compensate for
the distortions that occur during heat treatment.
160. Benefits of gear honing:
• Corrects dimensional errors
• Corrects distortions caused by heat treatment
• Removes nicks caused by handling
• Improves surface finishing
161. Gear forming vs Gear generation
Gear forming method Gear generation method
Separate cutter is required to produce
the required number of teeth.
Single cutter of any number of teeth
having the same pith.
Accuracy of tooth profile generated is
less
Accuracy is high
Low rate of production High rate of production
Internal and worm gears can be
produced
Internal and worm gears cannot be
produced
Methods are roll forming, end mill, disc
cutter
Gear shaping, gear hobbing and gear
tapping methods.
