The document summarizes the principle parts and operations of a lathe machine. It describes how the lathe holds workpieces between centers or in a chuck to rotate them while a cutting tool is fed against the workpiece. It then explains the main components of a lathe including the bed, headstock, spindle, carriage, saddle, cross-slide, compound, toolpost and tools. It also covers different types of lathes and work holding devices as well as common lathe operations like turning, facing, boring and threading.

1. PRINCIPLE OF LATHE MACHINE
THE LATHE IS A MACHINE TOOL WHICH HOLDS THE
W/P B/W TWO RIGID & STRONG SUPPORTS CALLED
CENTRES OR IN A CHUCK OR IN FACE PLATE WHICH
REVOLVES. THE CUTTING TOOL IS HELD AND FED
AGAINST THE REVOLVING WORK.CUTTING TOOL FED
EITHER PARALLEL OR AT RIGHT ANGLES TO THE AXIS
OF W/P. OR MAY ALSO AT AN ANGLE

2. LATHE SPECIFICATION
•
•
•
•
A-SWING
B-DISTANCE B/W CENTERS
C-LENGTH OF BED
D-RADIUS(ONE HALF OF SWING

3. PRINCIPLE PARTS OF LATHE

4. PRINCIPLE PARTS OF LATHE
1-BED AND WAYS
BED IS THE MAIN BODY OF THE LATHE MADE FROM STURDY CAST IRON. THE WAYS ARE
GROUND SURFACES ON THE TOP SIDE OF BED ON WHICH THE CARRIAGE AND TAILSTOCK RIDE

5. HEADSTOCK & SPINDLE
•
•
•
THE HEADSTOCK COMPRISES THE RECTANGULAR METAL CASTING AT THE LEFT END
OF THE LATHE .
IT CONTAINS THE SPINDLE SHAFT AND IT SUPPORTS BEARINGS AND HIGH/LOW
SPEED SHIFT LEVER AND GEARS.
SPINDLE IS THE MAIN ROTATING SHAFT ON WHICH THE CHUCK IS MOUNTED IT
SUPPORTED BY PRECISION THRUST BEARINGS.

6. CARRIAGE AND SADDLE
•
•
•
•
•
THE CARRIAGE SUPPORTS THE CROSS-SLIDE, COMPOUND AND TOOL POST.
MOVES ALONG THE WAYS UNDER MANUAL OR POWER FEED.
SADDLE RIDES ACROSS THE TOP OF THE WAYS AND THE APRON
SADDLE SUPPORTS THE CARRIAGE HAND WHEEL
CARRIAGE HAND WHEEL MOVES THE CARRIAGE ALONG THE WAYS BY MEANS OF A RACK
AND PINION DRIVE .

7. CROSS-SLIDE AND COMPOUND
•
•
THE CROSS SLIDE IS A DOVETAILED SLIDE THAT MOVES AT A RIGHT ANGLE TO THE WAYS.
THE COMPOUND SITS ON THE TOP OF THE CROSS SLIDE AND CAN BE ROTATED TO SET THE
TOOL TO ADVANCE AT AN ANGLE TO THE W/P.

8. TOOLPOST AND TOOLS
•
•
•
THE TOOLPOST CAN HOLD UP TO 4TOOLS AT ONCE ,EACH LOCKED IN PLACE BY HEXAGONAL
HEAD CAP SCREWS.
THE TOOLPOST ROTATE ALONG A LARGE BOLT ON THE TOP OF THE COMPOUND SLIDEAND IS
LOCKED IN PLACE BY CLAMPING LEVER.
TOOL CAN BE READYMADE CARBIDE TIP TOOLS.

9. TYPES OF LATHE
• Engine lathe
– Not production lathe, found in school shops,
toolrooms, and job shops
– Primarily for single piece or short runs
– Manually operated

10. Special Types of Lathes
Turret lathe
– Used when many duplicate parts required
– Equipped with multisided toolpost (turret) to
which several different cutting tools mounted
• Employed in given sequence

11. Special Types of Lathes
• Single- and multiple-spindle automatic lathes
– Six or eight different operations may be performed on
many parts at the same time
– Will produce parts for as long as required
• Tracer lathes
– Used where a few duplicate parts required
– Hydraulically operated cross-slide controlled by stylus
bearing against round or flat template

12. Special Types of Lathes
•
•
Conventional/programmable lathe
– Operated as standard lathe or programmable lathe to automatically
repeat machining operations
– 2-axis (DRO) so can see exact location of cutting tool and workpiece in
X and Z axes
Computerized numerically controlled lathes
– Cutting-tool movements controlled by computer-controlled program to
perform sequence of operations automatically

13. Work Holding Devices
THREE JAWS CHUCK
- For holding cylindrical stock centered.
- For facing/center drilling the end of your
aluminum stock
FOUR JAWS CHUCK
- This is independent chuck generally has four
jaws , which are adjusted individually on the
chuck face by means of adjusting screws

14. Collet Chuck
Collet chuck is used to
hold small workpieces
•
Thin jobs can be held by means of
magnetic chucks.
Magnetic Chuck
Thin jobs can be held by
means of magnetic chucks.

15. Lathe Centers

Work to be turned between centers must
have center hole drilled in each end
Provides bearing surface



Support during cutting
Most common have
solid Morse taper shank
60º centers, steel with carbide tips
Care to adjust and lubricate occasionally

16. LATHE DOGS
• LATHE DOGS ARE CAST METAL DEVICES USED TO PROVIE A FIRM
CONNECTION BETWEEN THE HEADSTOCK SPINDLE AND THE W/P
MOUNTED BETWEEN CENTRES.
T ail
T ail

17. MANDRELS
• MANDRELS IS USED TO HELD THE HOLLOW/DRILLED W/P.
•
W orkpiece
M andrel

18. RESTS
• LONG W/P NEED EXTRA SUPPORT THAT TEND TO SPRING
AWAY FROM THE TOOL BIT. WE USE THE REST FOR PROVIDE
SUPPORT.
Jaw s
W o rk
W o rk
H in ge
C arriage
L athe b ed g uidew ays
Jaw s

19. FACE PLATES
W orkpiece
• A LATHE FACE PLATE IS A FLAT ROUND PLATE THAT THREADS TO THE
HEADSTOCK SPINDLE TO THE LATHE.
• THE FACEPLATE IS USED FOR IRREGULARLY SHAPED W/P THAT CANNOT
SUCCESFULLY HELD BY CHUCKS.

20. Lathe Operations
•
Turning: produce straight, conical, curved, or grooved workpieces
• Facing: to produce a flat surface at the end of the part or for
making face grooves.
•
• Boring: to enlarge a hole or cylindrical cavity made by a previous
process or to produce circular internal grooves.
•
• Drilling: to produce a hole by fixing a drill in the tailstock
•
• Threading: to produce external or internal threads
•
• Knurling: to produce a regularly shaped roughness on cylindrical
surfaces

21. Lathe Operations

22. CUTTING PARAMETERS IN LATHE
CUTTING SPEED V=ΠDN/1000
• Where D= diameter of w/p in mm
N= r.p.m.
MACHINING TIME T= l/Fn
• Where l=length of w/p
f=feed in mm/rev.
N=r.p.m.
DEPTH OF CUT t= (D-d)/2,
where d=diameter of w/p after machining
METAL REMOVAL RATE(MRR) = ΠDtfN

23. REFERENCES
• Book
• Manufacturing Science-II BY- K.M. MOEED
• Website
• www. engbasics.com
• www. efunda.com