Henry Maudslay is considered the father of machine tool technology for his inventions around 1800, including a metal lathe that enabled mass production with interchangeable parts. A lathe is used to machine cylindrical workpieces and consists of main parts like the bed, headstock, tailstock, carriage, and tool post. Different lathe types include engine lathes, turret lathes, and automatic lathes. The document discusses lathe parts and mechanisms in detail.

1. RAMCO INSTITUTE OF TECHNOLOGY
Mr.M.LAKSHMANAN
Assistant Professor (Senior Grade)
Department of Mechanical Engineering

2. UNIT II
TURNING MACHINES

3. Father of Lathe
• Henry Maudslay (22 August 1771 – 14 February
1831) was a British machine tool innovator, tool and
die maker, and inventor.
• He is considered a founding father of machine
tool technology. His inventions were an important
foundation for the Industrial Revolution.
• Maudslay's invention about 1800 of a metal lathe to
cut metal enabled the manufacture of standard screw
thread sizes.
• Standard screw thread sizes allowed interchangeable
parts and the development of mass production.

4. File:Jan Verbruggen Foundry Drawing 47
Horizontal Boring Machine
Henry Maudslay developed
many improvements to the
lathe worked at the Royal
Arsenal from 1783 being
exposed to this machine in the
Verbruggen workshop.

5. Unit II Topics
Centre lathe, constructional features,
specification, operations–taper turning
methods, thread cutting methods, special
attachments, machining time and power
estimation. Capstan and turret lathes-tool
layout–automatic lathes: semi automatic–single
spindle : Swiss type, automatic screw type–
multi spindle:

6. Introduction
Machining
It is the process of cold working the metals into
different by using different types of machine tools.
Classification of machining processes
1.Metal cutting
(i) Single point cutting
• Turning
• Boring
• Shaping
• Planing

7. (ii)Multi-point cutting
• Milling
• Drilling
• Tapping
• Hobbing
• Broaching
2.Grinding and finishing
(i) Grinding
• Surface grinding
• Cylindrical grinding
• Centre less grinding
(ii)Finishing
• Lapping
• Honing
• super finishing

8. Centre Lathe
A lathe is a Father of all machine tools. Lathe is
a machine tool used to remove unwanted
material from a given workpiece to get
desired shape. It is generally used for
machining cylindrical workpieces.

9. Centre Lathe

10. Parts of Lathe or Constructional Features
of Lathe
• Bed
• Headstock
• Tailstock
• Carriage
• Feed mechanism
• Tool post
• Chuck

11. Bed
Bed is the base where all the lathe parts are
mounted. It is generally a single piece cast part
made of cast iron. Cast iron is used because of its
self lubricating property. Different Types of lathe
machines have different sizes of bed.
Lathe Bed are heavy rigid structure which is having
high damping capacity for the vibrations
generated by machines during machining.
The guide ways which are present on the top of the
bed will act as rails and supports other parts like
tail stock.

13. Headstock
Head stock is generally installed on the left side
of the lathe machine. It is a housing for the
drive pulleys and gears. The chuck is attached
in this part of lathe. With the help of chuck the
rotary motion is transferred to the work piece
.

14. Tailstock
• It is also sometimes called the Loose Head-
Stock Or Puppet Head. It is mounted on the
bed (inner ways) of the lathe.
• Tailstock is used for centering the job when a
long job is tied on the chuck. It provides a
good support to damp the vibration.

15. Carriage
Carriage holds the tools and provides movement of the
tool in both cross and longitudinal directions. It runs
through the outer ways.
The carriage will present between head stock and tail
stock which will slides on the bed ways of the lathe bed.
The carriage will give feed to the tool and it holds the
tool, for taper turning the feed is cross feed, for turning
it is longitudinal feed.
The carriage consists of the following parts.
• saddle
• cross-slide
• compound Rest
• Tool post
• Apron

17. Carriage

18. • saddle
It is the part of the carriage which slides along
the bed way and support the Cross-slide,
compound rest and Tool post.
• cross-slide
The cross-slide function is to provide cutting
action to the tool and the action of cutting tool
will be perpendicular to center line of lathe.It
can either be operated by hand, by means of
the cross-feed screw, or may be given power
feed through the Apron Mechanism.

19. • compound Rest
The compound Rest will be placed over the cross
slide and it consists of a graduated circular base
which is having swivelling nature.
• Tool post
It is the top most part of the carriage and is used for
holding the tool or tool holder in position.
Types of Tool post:
1. Single screw tool post
2. Open side tool post
3. Four bolt tool post
4. Four way tool post

20. Single screw Tool Post

21. Fourway Tool Post

22. • Apron
Apron houses the feed mechanism, clutch
mechanism split half nut, gears, leavers, The
apron wheel can be rotated by hand for
longitudinal motion of the carriage.

23. Specification of a Lathe
The size of the lathe is generally specified as follows;
• The length of bed
• Maximum distance between dead and love centres
• Type of bed
• Swing over the bed
• Swing over the cross slide
• Width of the bed
• Spindle bore
• Spindle speed
• HP of main motor and rpm
• Spindle nose diameter
• Feeds
• Floor space required

24. Size and specification of lathe

25. Types of Lathe
1. Speed lathe
Wood working lathe
Metal spinning lathe
Metal turning lathe
Polishing lathe
2. Engine or center lathe
Step cone pulley drive lathe
Geared lathe
Variable speed lathe
3. Bench lathe
4. Tool room lathe

26. 5. Semiautomatic lathe
Turret lathe
capstan lathe
6. Automatic lathe
7. Special purpose lathe
 Gap lathe
 Instruments lathe
 Facing lathe
 Heavy-duty lathe
8. Copying lathe

27. 1. Speed lathe
It is very simple is design. It only has headstock,
tailstock and a very simple tool post. It can
operate in 3-4 speeds. The spindle speed is
very high. It is used for light machine works
like wood turning, metal spinning and metal
polishing.

28. 2. Engine Lathe
Engine lathes are the most common types
of lathe machine. It is designed for low power
operations as well as high power operations. Various
lengths of the machine is available. The length can be
up to 6 feet. Engine lathe is commonly seen in
every machine shop. Various metals can be machines.
The machine can operates at a wide range of speed
ratios.

29. 3. Bench lathe
It is small sized engine lathe mounted on bench. It is
used for turning small and light weight workpiece.

30. 4. Tool room lathe
It is a very versatile lathe machine. It can give
better accuracy and finishing . It has wider range of
speeds . It can give different types of feeds. It can be
a great device to manufacture die.

31. 5. Semiautomatic lathe
It is a great machine for quick operations. It has
various types of tool posts mounted on a single
structure. As a number of tools are set up on
machine, the job can be completed very quickly with
the help of a single setup. A capstan wheel is used to
position the next tool. A sequential machining
process can be done by using the
turret lathe without moving the workpiece. It
eliminates the error that occurs due to
misalignment.

33. 6. Automatic lathe
An automatic lathe is a lathe whose actions are
controlled automatically. Although all
electronically controlled (CNC) lathes are
automatic, they are usually not called by that name,
as explained under "General nomenclature".

34. 7. Special purpose lathe
These lathes are modification of engine lathes
developed for machining special types of
workpices.

35. 8. Copying Lathe
Machine used for the reproduction of plane and curved
surfaces from a master (template, pattern, model, or
blueprint) on products made of various materials.
Copying lathes are made for plane, contour, three-
dimensional, and combined profiling with a mechanical,
hydraulic, electric, or photoelectric servomechanism or
without a servomechanism.

36. Headstock Mechanisms
Main parts of Head stock are:
• Headstock spindle
• Cone pulley
• Backgears and Backgear lever
• Gear box
• Live center
Types of Headstock Driving Mechanism:
1. Back geared headstock
2. All geared headstock

37. 1. Back Geared Headstock
Backgear is a clever but essentially simple
mechanism probably conceived around 1817 by
Richard Roberts,.
“Backgear" is a gear mounted at the back of the
headstock that allows the chuck to rotate slowly
with greatly-increased turning power.
By engaging backgear, and so reducing r.p.m. but
increasing torque, even the largest faceplate-
mounted jobs can be turned successfully.
Screw cutting also requires slow speeds, typically
between 25 and 50 r.p.m. - especially if the
operator is a beginner, or the job tricky.

39. Back Geared Headstock

40. Back Geared Headstock

41. 2. All Geared Headstock
Lathe which is equipped with All Geared Headstock is
easy to operate as there is no manual slip of Belt from
one step to any other. All Geared Lathe have three or
more than three shafts mounted within.
The gears are equipped to obtain different speeds,
which can be more than 18 spindle speeds. The middle
shaft has got three gears D,E & F as a single unit, thus
will rotate at similar speed.
The spline shaft also have three gears mounted as A,B &
C on it. The three gears can made to slide with the help
of the lever mounted in front of the Headstock.

43. All Geared Headstock

44. All Geared Headstock

45. This movement enables the Gear A to contact with the
Gear D or with other gears. This sliding movement on
the either of the shafts with the help of the levers,
different gears get in touch with each other & these
gears are connected to the main Spindle. So, with the
rotation of the Electric Motor Pulley, these gears are
also in drive and rotates the spindle, producing
different RPM.
All Speed Changes are done with the series of levers on
the front of the Headstock & are like shifting gears in a
Car.

46. The speed can be obtained is
G1/G4 x G4/G7
G2/G5 x G4/G7
G3/G6 x G4/G7
G1/G4 x G5/G8
G2/G5 x G5/G8
……
G3/G6 x G6/G9

47. Advantages
• Wide range of spindle speeds
• More efficient and compact than cone pulley
mechanism.
• Power available at the tool is almost constant for all
spindle speeds.
• Belt shifting is eliminated.
• The vibration of spindle is reduced.
• More power can be transmitted.

48. Feed Mechanism
Feed is defined as the movement of the tool
relative to the work. The feed mechanism is used
to transmit power from the spindle to the
carriage. It converts the rotary motion of the
spindle into linear motion of the carriage.
Three types of feeds can be given to the lathe
tool.
• Longitudinal feed
• Cross feed
• Angular feed

49. Types of Feed Mechanism
• Tumbler gear Reversing Mechanism
• Quick-Change gearbox
• Tumbler gear Quick-Change gearbox
• Apron Mechanism

50. Tumbler gear Reversing Mechanism
The tumbler Gear Mechanism can be described
as an arrangement of gear wheels which is used
to reverse the direction of rotation of any
machinery.
In this mechanism, the technique used is,
increasing the number of engaged gear wheels
which can easily be performed by pulling a liver.
In some industries or manufacturing units,
where thread cutting, or similar activities which
requires automatic feeding, this mechanism is
used.

53. Tumbler gear Reversing Mechanism

54. Quick-Change gearbox

55. Quick-Change Gearbox is used to get various power
feeds in the lathe.
Power from the lathe spindle is transmitted to feed
shaft through tumbler gear, change gear train and
quick-change gearbox.
The shaft B is connected to the shaft C through 4
cone gears.
Therefore, the shaft C can get 9X4 = 36 different
speeds.
The shaft C is connected to the lead screw by a clutch
and feed rod by a gear train.
The lead screw is used for thread cutting and the
feed rod is used for providing automatic feeds.

56. Tumbler gear Quick-Change gearbox

57. Tumbler gear Quick-Change gearbox
The different speeds for driving shaft are
obtained by a tumbler gear and cone gear
arrangement. It is simpler than the quick-
change gearbox. A Tumbler and a sliding gear
are attached to the bracket.
The driving shaft has a cone gear made up of
different sizes of gears.
By sliding the sliding gear to various positions
and engaging the tumbler gear, the different
speeds can be obtained.

58. Apron Mechanism

59. Apron Mechanism
It is used for transforming the rotary motion of the
feed shaft and the lead screw into feed motion of the
carriage.
Apron is attached to the carriage and hangs over the
front side of the lathe bed. It is
useful in providing power and hand feed to both
carriage and cross-slide. It is also used to
provide power feed to the carriage during thread
cutting through two half nuts.
Power is transmitted from the spindle to the lead-
screw and feed rod through the
spindle gear and tumbler gear arrangement. A worm
is mounted on the feed rod by a sliding
key.

60. Work Holding Devices
The work holding devices are used to hold and rotate the
workpieces along with the spindle. Different work
holding devices are used according to the shape,
length, diameter and weight of the workpiece and the
location of turning on the work.
Work holding devices are;
• Chucks
• Faceplate
• Angle plate
• Mandrels
• Carrier
• Centres
• Steady and follower rest

61. Chucks
Workpieces of short length, large diameter and
irregular shapes, which can not be mounted
between centres, are held quickly and rigidly
in chuck.
Types of chucks:
• Three jaw universal chuck
• Four jaw independent chuck
• Magnetic chuck
• Collet chuck and
• Combination chuck

62. Three Jaw self-centering chuck
The three jaws fitted in the three slots may be
made to slide at the same time by an equal
amount by rotating any one of the three
pinions by a chuck key.
This type of chuck is suitable for holding and
rotating regular shaped workpieces like
round or hexagonal rods about the axis of the
lathe.
Workpieces of irregular shapes cannot be held
by this chuck.

64. Four Jaw Independent Chuck
There are four jaws in this chuck. Each jaw is moved
independently by rotating a screw with the help of a
chuck key.
A particular jaw may be moved according to the shape
of the work.
Hence this type of chuck can hold woks of irregular
shapes. But it requires more time to set the work
aligned with the lathe axis. Experienced turners can
set the work about the axis quickly.
Concentric circles are inscribed on the face of the chuck
to enable quick centering of the workpiece.

66. Three Jaws Vs four Jaws
Three jaw Four jaw
This type consists of three
radial jaws
This type consists of four radial
jaws
These jaws can be moved
simultaneously
Each jaw moves independently
Minimum setting time More setting time
This chuck may be called
centering chucks or universal
chucks
This chuck may be called
independent chuck
Mainly used for holding round
or hexagonal bar
Mainly used for holding rough
castings, irregular shaped work
piece

67. Magnetic chuck
The holding power of this chuck is obtained by
the magnetic flux radiating from the
electromagnet placed inside the chuck.
Magnets are adjusted inside the chuck to hold
or release the work.
Workpieces made of magnetic material only are
held in this chuck. Very small, thin and light
works which can not be held in a ordinary
chuck are held in this chuck.

69. Collet Chuck
Collet chuck has a cylindrical bushing known as
collet. It is made of spring steel and has slots
cut lengthwise on its circumference.
So, it holds the work with more grip. Collet
chucks are used in capstan lathes and automatic
lathes for holding bar stock in production work.

71. Face plate
Faceplate is used to hold large, heavy and irregular
shaped workpieces which can not be conveniently
held between centres.
It is a circular disc bored out and threaded to fit to the
nose of the lathe spindle.
It is provided with radial plain and ‘T’ – slots for holding
the work by bolts and clamps.

73. Angle Plate
The angle plate is made from high quality material
(generally spheroidal cast iron) that has been
stabilized to prevent further movement or
distortion.
Slotted holes or "T" bolt slots are machined into the
surfaces to enable the secure attachment or
clamping of workpieces to the plate.

75. Mandrel
A previously drilled or bored workpiece is held on a
mandrel to be driven in a lathe and machined.
There are centre holes provided on both faces of
the mandrel.
The live centre and the dead centre fit into the centre
holes. A carrier is attached at the left side of the
mandrel.
The mandrel gets the drive either through a catch
plate or a driving plate. The workpiece rotates
along with the mandrel.

76. Types of mandrels
• Plain mandrel
• Threaded mandrel
• Step mandrel
• Cone mandrel
• Gang mandrel
• Expansion mandrel

78. Carrier
When a workpiece is held and machined between
centres, carriers are useful in trans- mitting the driving
force of the spindle to the work by means of driving
plates and catch plates. The work is held inside the eye
of the carrier and tightened by a screw.
Types of Carrier:
• Straight tail carrier
• Bent tail carrier

80. Centres
Centres are useful in holding the work in a lathe
between centres. The shank of a centre has Morse taper
on it and the face is conical in shape.
Types of centres:
• Live centre
• Dead centre

83. Steady and Follower rest
Rest is a device which supports long workpieces
L/D>10 or 12 when machined between centres or
held by a chuck. It prevents the vibration and
bending of the workpiece.
Types:
• Steady rest
• Follower rest

84. When the length and stiffness of a workpiece make it
difficult to machine without distorting or deflecting the
part, many manufacturers turn to the steady rest as a
workpiece support device.
This is especially true for long axles, shafts and similar
parts used in automotive or heavy equipment
applications, and in oil drilling components.

86. Lathe Operations
• Facing
• Turning
– Straight turning
– Step turning
• Chamfering
• Grooving
• Forming
• Knurling
• Undercutting
• Eccentric turning
• Taper turning
• Thread cutting
• Drilling
• Reaming
• Boring
• Tapping

87. Facing
Facing is the operation of machining the ends of
a piece of work to produce flat surface square
with the axis. The operation involves feeding
the tool perpendicular to the axis of rotation
of the work.

88. Turning
Turning in a lathe is to remove excess material
(diameter) from the workpiece to produce a
cylindrical surface of required shape and size.
Rough Turning:
(DOC =2 to 5mm, Feed =0.3 to 1.5mm/rev)
Fine Turning:
(DOC = 0.5mm to 1mm, Feed = 0.1 to
0.3mm/rev)

89. Chamfering
Chamfering is the operation of bevelling the
extreme end of the workpiece. The form tool
used for taper turning may be used for this
purpose. Chamfering is an essential operation
after thread cutting so that the nut may pass
freely on the threaded workpiece.

90. Grooving
Grooving is the process of cutting a narrow
groove on the cylindrical surface of the
workpiece. It is often done at end of a thread
or adjacent to a shoulder to leave a small
margin. The groove may be square, radial or
bevelled in shape.

91. Forming
Forming is a process of turning a convex,
concave or any irregular shape. For turning a
small length formed surface, a forming tool
having cutting edges conforming to the shape
required is fed straight into the work.

92. Knurling
Knurling is the process of embossing a diamond
shaped pattern on the surface of the workpiece.
The knurling tool holder has one or two hardened
steel rollers with edges of required pattern. The
tool holder is pressed against the rotating work.
The rollers emboss the required pattern. The tool
holder is fed automatically to the required length.
The purpose of knurling is
• to provide an effective gripping surface
• to provide better appearance to the work
• to slightly increase the diameter of the work

93. Knurling

94. Undercutting
Undercutting is done
• at the end of a hole
• near the shoulder of stepped cylindrical
surfaces
• at the end of the threaded portion in bolts
It is a process of enlarging the diameter if done
internally and reducing the diameter if done
externally over a short length. It is useful
mainly to make fits perfect. Boring tools and
parting tools are used for this operation.

95. Undercutting

96. Eccentric turning
If a cylindrical workpiece has two separate axes
of rotating, one being out of centre to the
other, the workpiece is termed as eccentric
and turning of different surfaces of the
workpiece is known as eccentric turning. The
distance between the axes is known as offset.
Eccentric turning may also be done on some
special machines.

98. Drilling and Reaming

99. Boring operation

100. Taper turning
A taper may be defined as a uniform increase or
decrease in diameter of a piece of work
measured along its length.
Taper turning methods:
• Form tool method
• Compound rest method
• Tailstock setover method
• Taper turning attachment method
• Combined feed method

101. 1. Form tool method
A broad nose tool is ground to the required
length and angle. It is set on the work by
providing feed to the cross-slide. When the
tool is fed into the work at right angles to the
lathe axis, a tapered surface is generated.
This method is limited to turn short lengths of
taper only. The length of the taper is shorter
than the length of the cutting edge. Less feed
is given as the entire cutting edge will be in
contact with the work

103. 2. Compound rest method
The compound rest of the lathe is attached to a
circular base graduated in degrees, which may
be swivelled and clamped at any desired angle.
The angle of taper is calculated using the
formula

104. The important feature is that the compound
rest can be swivelled up to 45° on both sides.
Only with the help of the hand the tool should
be moved.

105. 3. Tailstock set over method
Turning taper by the set over method is done by
shifting the axis of rotation of the workpiece at an
angle to the lathe axis and feeding the tool parallel to
the lathe axis. The construction of tailstock is
designed to have two parts namely the base and the
body. The base is fitted on the bed guideways and
the body having the dead centre can be moved at
cross to shift the lathe axis.
The dead centre is suitably shifted from its original
position to the calculated distance. The work is held
between centres and longitudinal feed is given by
the carriage to generate the taper.

106. The advantage of this method is that the taper can be
turned to the entire length of the work. Taper threads
can also be cut by this method.
The amount of setover being limited, this method is
suitable for turning small tapers (approx. upto 8°).
Internal tapers cannot be done by this method.

108. 4. Taper turning attachment method
The taper attachment consists of a bracket which is attached
to the rear end of the lathe bed. It supports a guide bar
pivoted at the centre. The bar having graduation in
degrees may be swivelled on either side of the zero
graduation and set at the desired angle to the lathe axis. A
guide block is mounted on the guide bar and slides on it.
The cross slide is made free from its screw by removing
the binder screw. The rear end of the cross slide is
tightened with the guide block by means of a bolt. When
the longitudinal feed is engaged, the tool mounted on the
cross slide will follow the angular path as the guide block
will slide on the guide bar set at an angle of the lathe axis.
The depth of cut is provided by the compound slide which
is set parallel to the cross-slide.

110. The advantage of this method is that long tapers can
be machined. As power feed can be employed, the
work is completed at a shorter time. The
disadvantage of this method is that internal tapers
cannot be machined.

111. 5. Combined feed method
Feed is given to the tool by the carriage and the
cross-slide at the same time to move the tool at
resultant direction to turn tapers.

112. Thread Cutting

113. Threading

115. Driver teeth Number of teeth on spindle gear
=
Driven teeth Number of teeth on lead screw gear
Pitch to be cut on work
=
Pitch of the lead screw

116. Types of gear trains in thread cutting
• Simple gear train
• Compound gear train

119. Lathe (special) attachments
• Taper turning attachment
• Milling attachment
• Grinding attachment
• Copy Turning attachment
• Spherical Turning attachment

120. 2. Milling Attachment

121. 3. Grinding attachment

122. Grinding attachment

123. 4. Copy Turning attachment
To machine the complex contours on the work
which require the feeding of the tool in two
axes (X and Y axes) simultaneously similar
to taper turning.
Types of Copy Turning:
• Mechanical type
• Hydraulic type

124. Mechanical -Copy Turning attachment

125. Hydraulic - Copy Turning attachment

126. 5. Spherical Turning attachment

127. Cutting speed, Feed & Depth of cut
Cutting speed
It is the peripheral speed of the work piece past
the cutting tool.
𝑉 =
𝜋𝐷𝑁
1000
V= cutting speed m/min
D=diameter of the job, mm
N=job or spindle speed r.p.m

128. Feed
Feed may be defined as the distance that a tool
advances into the work during one revolution of the
headstock spindle.
Feed is expressed in mm/revolution.
f=
𝐿
𝑁𝑋𝑇 𝑚
L=length of cut, mm
N=r.p.m
Tm=machining/cutting time, in min.

129. Depth of cut
The depth of cut ‘d’ is the perpendicular
distance measured from the machined surface
to the uncut surface of the work piece.
d=
𝐷𝑖
−𝐷𝑓
2
mm
Di=initial diameter of the work piece, mm
Df= final diameter of the work piece, mm

130. Material Removal Rate (MMR)
• It is the volume of material removed per unit
time.
• Volume of material removed in one
revolution=πDi X d X f mm3
• MMR=πD
i
X d X f X N mm3/min
• MRR=1000X V X dX f mm3/min
• D
i=initial diametre of the workpiece,mm
• d= depth of cut,mm
• f=feed,mm/revolution

131. Estimation of Machining Time (Tm)

134. Sample Problem

136. Limitation of a Centre Lathe
• Only one tool can be used in the normal
course
• Large setting time of the job
• The idle times involved in setting and
movement of tools.

138. Special Purpose Lathes
• Semi –Automatic lathes
All machining operations are automatically
performed.
But the loading and unloading the job, bring the tools
in correct position, coolant on or off and selection of
spindle speeds are manually performed.
Capstan and Turret Lathe
• Automatic lathes

139. Capstan Lathe

142. Capstan lathe
Capstan lathe is one of the types of semi-automatic
lathe. In semi-automatic lathes machining operations
are done automatically. Functions other than
machining like loading and unloading of job,
positioning of tools coolant operations are done
manually.

143. Main parts of Capstan Lathe
• Bed
• Headstock
• Turret head

144. 1. BED
The base part of the lathe is the bed. It is made of
cast iron.
Guide ways are provided on the top of the bed.
Cross slide and turret head are mounted on the guide
ways.
The bed should be strong and rigid to withstand
loads force and vibrations during machining process.

145. 2. HEAD STOCK
The headstock assembly is permanently
fastened to the left end of the bed.
Headstock of capstan lathe is similar to that of
ordinary lathe. But it is heavier in
construction .
A powerful motor of 30 to 2000rpm speed is
fitted.

146. Types of Headstocks
• Step cone pulley driven headstock.
• Direct electric motor driven headstock .
• All geared headstock.
• Pre-selective headstock

147. 3. TURRET HEAD AND SADDLE
The turret head is mounted on the ram fitted with
turret slides longitudinally on the saddle. Turret head
has a hexagonal block having six faces with a bore for
mounting six or more than six tools at a time.
The threaded hole on these faces are used to hold the
tools. The actuation of ram is done by hand or power.
An adjustable stopper is used to control the forward
movement of the ram.

149. Ram is returned to its initial position in order to index
the cutting tool. The tools are indexed to 60 by rotation
of circular plate which is indexed automatically along
with the turret head. For bringing the next tool into
cutting position a mechanism called Geneva
mechanism is used.
It is an H shaped component fitted across the lathe bed.
It moves along the guide way. It can be moved
anywhere along the bed and locked to the required
position.
In capstan lathe the turret head is mounted upon the
ram which slides upon the saddle.

150. 4.CROSS SLIDE
There are two type of cross slides they are
• Reach over type
• Slide hung type
• Reach over type
The cross slide has two tool posts having totally
four faces of square turret for mounting the tools.
Tools are indexed by an angle of 90. While indexing,
the motion of each tool is controlled by stop bars.
• Slide hung type
This type of cross slide is entirely supported on the
front and has no rear tool post. This enables a
greater swing capacity to hold large diameter
workpiece.

151. WORKING PRINCIPLE
Work piece is held in collet or chucks which is
actuated hydraulically or pneumatically. All the
needed tolls are held in the respective holes on
the turret head. According to the sequence of
operation the tool is moved with the help of
turret head.
• Drilling, boring, turning, reaming, threading
tools are mounted on the turret head.
• Forming, chamfering, knurling tools are
mounted on the front end of the turret.

152. ADVANTAGES
• Rate of production is higher.
• Different ranges of speeds are obtained.
• More number of tools can be accommodated.
• Chucking of larger work pieces can be done.
• Operators of less skill is required hence lowers
the labour cost.
• Higher rigidity so can withstand heavy loads.

153. Turret Lathe

154. Schematic Diagram of Turret Lathe

155. Main Parts of a Turret Lathe
• Bed
• Headstock
• Turret head

157. Turret Vs Capstan Lathe
Aspects Turret lathe Capstan lathe
Turret position Turret(head) is mounted
directly on the saddle
turret head is mounted on a
ram. The ram slides on a
saddle
Feeding of
tools
For feeding the tools entire
saddle is moved
The saddle is fixed at a
convenient distance from the
work and the tools are fed by
moving the slide.
Extent of
rigidity
Very high rigidity Low rigidity
Capability to
handle jobs
It is heavy duty machine large
work piece are clamped in a
chuck or power operated
chucks.
It is light duty machine
Maximum bar
size that can
be handled
Upto 200 mm diameter Upto 60mm diameter

158. Turret Vs Capstan Lathe
Aspects Turret lathe Capstan lathe
Tool travel Almost full length of the
bed
Limited tool travel
Rate of tool
feeding
The tool traverse is slower
and offers more fatigue to
the operator's hands
The tool traverse is
faster and offers
less fatigue to the
operator's hands
Type of
carriage
Reach-over type or side
hung type
Reach-over type
only
Other
provisions
Heavier designs are
usually provided with
pneumatic chucks to
ensure a firmer grip over
heavy jobs
These lathes do not
have such
provisions

159. Geneva Mechanism or Indexing Mechanism
The turret is provided with automatic
indexing mechanism. The Geneva mechanism
is used in Turret lathes and automatic lathes.
It’s a mechanism that translates a continuous
rotation into an intermittent rotary motion.
Turret head, an index plate, bevel gear and
ratchet are mounted on the same vertical
spindle of the saddle.

163. In turret and capstan lathes, the bar is
automatically fed without stopping the lathe
which reduces the production time. The bar
stock passes through the chuck and hollow
spindle of the lathe.

164. Automatic lathes
Advantages
• Increased productivity
• Reduced unit cost
• Better utilization of the resources
• Improvement in accuracy
• Floor are reduced

165. Disadvantage
• Not suitable to machine heavy component
• Cost of machine skilled tool setters
• Tooling cost is high
• It is not economical for single piece
production

167. Classification of Automatic Lathes
(i) Automatics
(a) Single spindle
-Cutting off
-Swiss type
-Automatic screw type
-Special
(b) Multiple spindle
-Cutting off
-Drilling,forming,cutting off bar
-Bar
-Special type

168. Single spindle Automatic Lathe
• A single spindle automatic lathe is a modified form of
turret lathe. These machines have an addition to a 6-
station turret, a maximum of 4 cross slides. These
cross slides are operated by disc cams. The cams are
mounted on a shaft which draws the power from the
main spindle through a set of gears called cyclic time
change gears. Turret operation is also synchronized
with the cross slide operation and is driven by
another cam called main cam.
• The tools used on the cross slides are usually form
tools and are plunged into the work piece at the
desired feed rate. The tools used in the turret may be
turning tool, drilling tools etc. It is general to use more
than one tool on a turret station. External threading is
usually carried out by a thread chasing attachment.
Internal threads are made using taps.

170. Types of single spindle automatics
• Automatic cutting off machine
• Automatic screw cutting machine
• Swiss type automatic screw machine

171. 1. Automatic cutting off machine

172. Automatic cutting off machine
These machines are simple in design and they
are used for producing large quantities of
parts of smaller diameter and shorter length.
The components of simple shapes are
produced in this machine.

173. 2. Single spindle Automatic screw cutting
machine

174. Single spindle Automatic screw cutting
machine
These machines are essentially automatic bar
type turret lathes. Its widely used for the
production of all sorts of small turned parts.
It mainly consists of a cross slide and turret.
Its used for producing small jobs, screws,
stepped pins, taper pins, bolts, etc.

175. 3. Swiss Type Automatic Screw Machine or
(Sliding Head Automatic Lathe)

177. Swiss Type Automatic Screw Machine or
(Sliding Head Automatic Lathe)
This type of automatic lathe is suitable for small,
long and slender parts such as parts of wrist
watches. The headstock carrying the bar stock
moves back and forth for providing the feed
movement in the longitudinal direction. Its also
called sliding head automatic lathe.
Its used for producing long accurate parts of small
diameter (2 to 25mm). The parts can be
machined to an accuracy of 0.005mm to
0.o125mm.

178. Advantages
• High rate of production
• Machined to an accuracy of 0.005mm to
0.0125mm
• Wide range of speed
• Designing of cam is simple
• Tool setting time is reduced

179. Multi Spindle Automatic Lathe Machines
Multi Spindle Automatic Lathe can provide the
various types of machining such as boring,
turning, chamfering, threading, grooving, and
drilling by moving the workpieces between 6 or 8
stations(machining position). This machine tool
enables to realize overwhelmingly fast cycle time
by dividing into 6 or 8 processes. Generally Multi
Spindle Automatic Lathe can provide approx. 4－
5 times of machining speed comparing to the
Single Spindle NC Lathe although the speed can
be widely varied depending on the various
conditions.

181. Classification of Multi Spindle Automatic Lathes
1. According to the type of workpiece(stock)
used
 Bar type machine
 Chucking type machine
2. According to the arrangement of spindle
 Horizontal spindle type
 Vertical spindle type
3. According to the principle of operation
 Parallel action type
 Progressive action type

182. Parallel Action Multi Spindle Automats

183. Parallel Action Multi Spindle Automats
In this machine same operations are
performed on all spindle of the machine.
This machine consists of a frame with a
headstock. The axes of work spindles are
horizontal. These spindles are arranged in a
line one above the other.
There are two cross slides, one on the left
hand side (Front tool slide) and the other on
the right hand side (Rear tool slide).

184. Progressive action Multi Spindle Automats

185. Progressive action Multi Spindle Automats
In this type of machine, the workpieces are
machined in stages. The headstock is
mounted on the base of the machine. The
headstock has a spindle carrier. The
working spindles are mounted in the
spindle carrier. Workpieces are held by the
collet in the spindles.

186. Automatic Vs Semi-Automatic Lathe
Automatic Semi-Automatic
Loading and unloading of
work piece are done
automatically by the machine
Loading and unloading are
done manually
Machining positions are done
automatically
Theses are done manually
A single operator can attend a
number of machines
An operator can attend to only
one or two machines at a time
Production time and cost is
less
more
Best suitable for production of
small size components
Suitable for large size
components
Initial cost is high Initial cost is low

187. Single Spindle Vs multi-spindle
Single Spindle multi-spindle
• It has one spindle • It has more than four
spindles
• Low rate of production • High rate of production
• Only one job is
machined at a time
• More than 4 jobs are
machined at a time
• Machining accuracy is
higher
• Machining accuracy is
lower
• Tooling cost is low • Tooling cost is more

188. Parallel Action M/C Vs Progressive Action M/C
Parallel Action M/C Progressive Action M/C
• Same operation is done • Different operation are done
• In one cycle number of
components produced
Symentantially is equal to the
number of spindle.
• number of components
produced in one cycle is not
equal to the number of spindle
• Rate of production very high • Moderate
• Small parts of simple shape
are produced
• Complicated parts are
produced
• If anything goes wrong in one
station in the production in
that particular station only
affected.
• Completely all station affected.

189. Tool Layout
Turret and Capstan lathes are mainly used for
machining workpieces at a rapid rate. Before
starting the production, the following works are
carried out.
• Selection of tools
• Designing of special tools
• Selection of speed
• Selection of feed
• Setting required length of workpiece and tool
travel length.
These planning operation sequence and
preparation of turret or capstan are termed as
Tool Layout.

190. Stages of Tool Layout
• Planning and scheduling stage: Preparation of
operation sheet with the order of operation.
• Detailed sketching of various stages of
machining operation in a sequence of
operation.
• Sketching the plan showing the various tools
fitted into the hexagonal turret faces and on the
cross slides in a proper sequence.

191. Hexagonal bolt

192. Tool layout for hexagonal bolt
Step
1. Select the proper Machine- Turret lathe
2. Select the proper material-a hexagonal steel bar
3. Collect all the tools and equipments-barstop,box
turning tool, bar ending tool, Die head, chamfering
tool, parting tool
4. Draw the tool layout
5. Calculate proper speeds and feeds for each
operation.
6. Determine the sequence of various operation
7. Prepare the tooling schedule chart.

193. Tool layout for hexagonal bolt

194. Tooling Schedule Chart