The document provides information about lathe machines and their operation. It defines a lathe as a machine tool that removes metal from a workpiece to give it a desired shape and size. It then discusses several topics in lathe operation: 1) The major factors considered for selecting cutting speed on a lathe including material type, tool life, dimensions, finish, depth of cut, and machine rigidity. 2) The different classifications of lathe machines including speed, engine, bench, tool room, capstan, turret, special purpose, automatic, and CNC lathes. 3) The basic parts of a center lathe and their functions, which include the bed, headstock, tail

1. LATHE MACHINE
BY
LECTURER TIRTHARAJ CHINDARKAR
BHAUSAHEB VARTAK POLYTECHNIC COLLEGE, VASAI (WEST)

2. DEFINITION
• LATHE machine is a machine tool that is used
to remove metals from a work piece to give a
desired shape and size.
• To cut the material properly the tool should be
harder than the material of the work piece.

3. Q.1) State and explain the major factors considered
for selection of cutting speed in lathe machine?
• The type of material
• Tool life and tool material
• The dimensions of cutting tool
• Surface finish required
• The depth of cut
• Rigidity of machine and work setup

4. Q.2) How lathe machines are
Classified?
1. Speed lathe 2. Engine lathe
3. Bench lathe 4. Tool room lathe
5. Capstan and turret lathe
6. Special Purpose:
a) Wheel lathe b) Gap bed lathe
c) T- lathe d) Duplicating lathe
7. Automatic lathe
8.CNC lathe

5. SPECIFICATION OF CENTER
LATHE
A- Max. distance between
centers
B- Height of centers over bed
C- Max. swing over carriage
D- Max. swing over Bed
E- Length of bed
• Width of bed, headstock motor horse power, height of
the lathe machine, overall dimensions of machine

6. Q.3) Basics Parts of Centre lathe and
their Functions

7. • CENTRE LATHE:
It is also called Engine lathe because the first of
this type of lathe was driven steam engine.
It has Two canters between which job is held and
rotated.
BASIC PARTS OF CENTRE LATHE:
1)Bed 2)Headstock 3)Tailstock
4)Carriage 5) Feed mechanism
6)Screw cutting mechanism
7) Main drive

8.  THE BED:
a) The lathe bed forms the base of the machine.
b) It is the foundation of the machine and it holds
all other parts of the lathe in their correct relative
positions.
C) Headstock and Tailstock located end of the bed.
HEAD STOCK:
a) The headstock is secured permanently on the
inner ways at the left hand end of the lathe bed
b) Its provides means of rotating the work at
multiple speeds

9.  TAIL STOCK
a) Tail stock is located on the inner ways at the
right hand end of the bed.
b) It supports the other end of the work when it is
being machined between centers.
c) It hold a tool for performing operations such as
drilling, reaming. Tapping, etc.
 CARRIAGE
It serve to support , move and control the
cutting tool.
i)Saddle ii)cross-slide iii) Compound slide iv)Tool-
post v)Apron

10.  FEED MECHANISM
a) The movement of the tool relative to the
termed as “Feed”.
b) When the tool moves parallel to the lathe
axis, the movement is termed as longitudinal
feed and is effected by movement of the
carriage.
c) When the tool moves at right angle to the
lathe axis with the help of a cross slide the
movement is termed as cross feed.

11.  SCREW CUTTING MECHANISM
The lead screw and the half nut mechanism are
used to produce Screw thread
 MAIN DRIVE
The primary motion is obtained by an
electric motor that drives the spindle
through a cone pulley system or through
an all geared drive

12. LATHE ACCESSORIES
• DEFINATION:
 Accessories of the a machine, are the devices
which are used on the machine for the purpose of
holding and supporting the work piece and tool.
In other word, the accessories supports the
machining operations.
Some Important accessories
(I) Chucks (II)Mandrels (III)Rests
(IV)Face plates (V)Centers (VI)Angle plates

13. CHUCKS
Chucks hold and rotates the job with the help
of its adjustable Jaws.
It is basically screwed or threaded to the
headstock spindle.
Types of CHUCKS:
a) Three Jaw chuck or universal chuck
b) Four Jaw independent chuck
c) Magnetic chuck

14. A) THREE JAW CHUCK OR
UNIVERSAL CHUCK
• It is used to hold round
and hexagonal work
• Made in common size
Approx. 100 to 400 mm
in diameter
• The movement of Three Jaws take place at the
time
• It is also known as Self Centered Jaw chuck

15. B) FOUR JAW CHUCK
• The arrangement of four jaws independent
chuck, which has four jaws, located at an
angle of 90°
to each other.
• Each jaw made
of tough steel
has three inner
and one outer gripping surface

16. C) MAGNETIC CHUCK
• The chuck is used for holding a very thin work
piece made of magnetic material which
cannot be held in an ordinarily chuck
• The holding power of the chuck is obtained by
the magnetic flux radiating either from the
electromagnets or from the permanent
magnets introduced within the chuck.

17. MANDRELS
Lathe mandrels are devices used to hold for job
machining on lathes.
It has 600 centers on both sides and it holds and
locate a part from its center hole
Mandrels are used for turning of bushes, gear
blanks, pulleys etc.

18. RESTS
 Rests are the devices used to support lengthy
or long work piece which are held between the
centers to prevent the bending of job
 The job may bend during
turning because of its weight
And cutting forces.
 Two types of rests are
commonly used :
I) Steady test II) Follower test

19. FACE PLATE
• It is round disk which has a threads inside the
bore to fit on to the nose of the spindle.
• It is specially used for
those jobs which are
heavy, too large and or
uneven in shape.

20. CENTRES
LIVE CENTER
DEAD CENTER

21. ANGLE PLATE
• An angle plate is a precision L-shaped piece
which both faces are machined 900 to each
other with greater accuracy.
• It is made up of cast iron or
Hardened steel.
• It has slots and holes cuts on its both faces
used for clamping the work
by means of bolts and clamps

22. LATHE OPERATIONS
Q.1) STATE THE VARIOUS OPERATIONS
PERFORMED ON THE LATHE. EXPLAIN ANY TWO IN
BRIEF.
1) Turning :- a)Straight b)Step c) Taper
2) Facing
3) Thread cutting
4) Knurling
5) Drilling
6) Boring
7) Parting off
8) Grooving
9) Chamfering

23. 1] TURNING
• A machining process in which a single-point
tool material from the surface of a rotating
work piece
a) Straight Turning b)Step turning

24. C) Taper Turning:
• Taper turning as a machining operation is the
gradual reduction in diameter from one part
of a cylindrical work piece to another part.

25. Taper Turning Methods
• In lathe, the taper can be turned by any one of
the following methods
i)Swiveling of the compound rest
ii) Setting over the tailstock center
iii)By using broad nose form tool
iv)By a taper turning attachment

26. i)Swiveling of the compound rest
tan α = (D-d)/2L
Where D and d are large
And small dia. & L is length
ii) Setting over the Tailstock Center
sin α = BC/AB

27. iii)Broad nose form tool
iv)Taper Turning Attachment

28. 2] FACING 3] THREAD CUTTING
4] KNURLING 5] DRILLING

29. 6] BORING 7] PARTING OFF
8] GROOVING 9] CHAMFERING

30. DIFFERENCE BETWEEN ORTHOGONAL
AND OBLIQUE CUTTING
SR NO. ORTHOGOANAL CUTTING OBLIQUE CUTTING
1 Tool cutting edge make 90° with
path of movement of tool
Tool cutting edge makes angle other than
90° with tool line of action
2 2-dimensional cutting 3-dimensional
3 Tool life shorter longer tool life
4 Analysis is simple Analysis is complex
5 Two mutually perpendicular cutting
forces act on the work piece
Two mutually perpendicular cutting
forces act on the work piece
6 More heat generated for the same
amount of work
Less heat generated for the same
amount of work
7 Limited application Wide application
8 It removes less metal during its life It removes more metal in the same life of
orthogonal cutting tools