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Lathe Machine-Introduction,Working Principle,Parts,Operations,Specifications

INTRODUCTION:

  • Lathe machine refers to a machine tool which used to remove unwanted metals from the work – piece to give desire shape and size.

 

  • Lathe machine is one of the most important machine tools which is used in the metal working industry.

 

  • It operates on the principle of a rotating work piece and a fixed cutting tool.

 

  • The cutting tool is feed into the work piece which rotates about its own axis causing the work piece to formed the desired shape.

 

  • It is also known as ” the mother/father of the entire tool family”.

 

  • It was invented by  DAVID WILKINSON ( 05 Jan. 1771 – 03 Feb. 1852 ) .

 

main parts of lathe machine

Definition of lathe machine

  • The machine tool that ‘s use to remove unwanted metals from the work – piece to give desire shape and size so called as Lathe machine.

 

  •  Lathe machine is also known as “ Center Lathe ” because of two centers between which the job can be held and rotated

Main Parts of lathe 

  • The main parts of  lathe machine are :-

 A. Bed 

  • Bed is the main body  of a lathe which provides supports to all parts of the machine .
  • The bed is heavy, rugged casting which is mounted on the working parts of the lathe.

 B.  Head Stock

  • They having spindle shaft and support bearings, speed shift levers and gear trains .
  • The head stock spindle is a hollow cylindrical shaft that provides a drive from the motor to work holding devices.
  • Head stock is hidden in a box and  spindle is hidden in a gear cover.

  C. Tail Stock 

  • The main function of tail stock to support the job.
  • Tail stock is  situated on bed.
  • It can be offset for taper turning operations.

 D. Lead Screw

  • It is  used to transmit power  to carriage through gear  and clutch arrangement in the carriage apron.

  E. Carriage and Saddle

  • Carriage supports cross – slide , compound rest and tool post and it moves along the ways under manual or power feed.
  • It comprises the saddle a casting , which rides across the top of the ways and the apron .
  • Compound slide permits angular tool movement for taper turning .

 F.  Cross Slide and Compound slide

  • Cross slide is a dove tail slide which is assembled on the top of the saddle and moves at right angle to the ways.
  • Compound slide supports the tool post and cutting tool in its various positions and it is above the cross slide and it can be rotated to set the tool to advance cutting of work piece .

G. Feed Mechanism

  • Feed mechanism is used to transmit power to carriage .
  • Gear train system is provide.

H. Tool Post 

  • Tool Post is used to hold the tool at correct position.
  • It’s bolt on the carriage.
  • It may set at any desire angle.

I. Apron

  • It is situated on the carriage.
  • It consist all controlling and moving mechanism of carriage.

J. Spindle

  • It is the main part of lathe which holds and rotates the chuck.

K. Live Center

  • A Live Center is mount on bearings and rotates with the work.
  • Live centers are using to hold or support a work-piece.

L. Dead  Center

  • A dead center may be used to support the work piece at either the fixed or rotating end of the machine.
  • Dead centers are typically fully harden to prevent damage to the important mating surfaces of the taper and to preserve the 60° angle of the nose.

Functions of lathe machine 

  • To producing cylindrical jobs.
  • Flats surface and holes.
  • It’s use for producing different types of surfaces ,cutting threads ,cutting grooves.

Working Principle of lathe machine

 Principle

  • The lathe is a machine tool which use to removes unwanted materials  from a work piece in the form of chips with the help of a tool which travels across the work piece and can be fed deep in work.

Principle Diagram of Lathe machine

 

  • When tool is moved parallel to the work piece then cylindrical surface is formed.

Working Principle 1

  • If the tool is moved inclined to the axis then it produce a taper surface and so call as taper turning.

Working Principle of Lathe 2

 Working

  • It holds the work between two supports so call as centers.
  • Face plate or Chuck are using for holding the work.
  • Face plate or Chuck are mount on machine spindle.
  • The cutting tool is holding with the help of Tool post.
  • The movement of the job is rotating about the spindle axis.
  • Against the revolving work, the tool is feed.
  • The tool is moved either parallel or inclination to the work axis.

Lathe Operations & Machine Tools

OPERATIONS DIAGRAM MACHINE TOOL
  Tapper Turning Taper turning   Turning Tool
Facing Facing Facing Tool
Drilling Drilling Drilling Tool
Boring Boring Boring  Tool
Internal & External Threading Threading Tool
Knurling  Knurling Knurling Tool
Grinding Grinding wheel Tool Post Grinding
Parting Parting tool Parting  Tool
                                                                                                           

 Operations of lathe

1. Turning

  • Turning is an operation in which diameter of the work piece is remove as shown in above table.

2. Facing

  • Facing is an operation in which length of the work piece is reduce as shown in table.
  • Turning tool is use.

   a.  Feed

  •  The rate at which the cutting tool crosses the work piece in the direction perpendicular to work piece axis so call as feed.

   b.  Depth of cut

  • It is the perpendicular distance measured from the machine surface to the UN – cut surface of the work piece.

3. Drilling

  • Drilling is an operation to produce a hole on the work piece.

4.  Boring

  • Boring is done to enlarge a hole or cylindrical cavity to produce circular internal grooves.

5.  Knurling

  • Knurling is done to produce regular pattern type roughness on the work piece.
Types of lathe machine

         Lathe machines are classify according to their construction and design. Some of them are:

   1. Bench lathe

   2. Speed lathe

   3. Engine lathe or center lathe

   4. Tool room lathe

   5. Capstan and turret lathe

   6. Special purpose lathe

   7. Automatic lathe

   1. Bench lathe

  • Bench lathe is a small lathe usually mount on a bench.
  • This is using for small and precision work.

   2. Speed lathe

  • Speed lathe is the simplest of all types of lathe in construction and operation.
  • It consists of a bed , a head stock, a tail stock and a tool – post mounted on an adjustable slide.
  • The spindle speed is about 4000 rpm.
  • They are named  because of very High Speed of head stock  spindle.

   3. Engine lathe ( center lathe )

  • The term ” engine ” is associated with the lathe which is early driven by steam engines.
  • An engine lathe is also known as a reproductive machine because of  their production capabilities.
  • Engine lathes are an excellent tool, which aids in the creation of many modern tools.

Advantages

  • It is using for mass production of products.
  • It is using for manufacturing cylindrical shapes like steels and plastics.

Disadvantages 

  •  It is very difficult to program in machine language
  • corruption, poor service, and racial issues.

 

4.TOOL ROOM LATHE 

  • Tool room lathe is similar to an engine lathe.
  • This lathe is mainly using for precision work on tools ,Dies,Gauges and in macing work where accuracy is need.
  • It is used for making precision components in the tool room.

5.CAPSTAN AND TURRET LATHE https://mechanicalnotes.com/2019/02/05/capstan-turret-lathes-machine/

  1. Capstan Lathe

CAPSTAN LATHE

  • They having features of the basic lathe and have short slide tail stock.
  • A Capstan machine is a processing machine uses for making the same parts again and again.

Advantages

  • The production rate is high.

Disadvantages

  • The heavier work piece cannot machine by  capstan lathe.

b.TURRET LATHE 

  • The turret lathe is a form of metal working lathe.
  • It is used for repetitive production of duplicate parts.
  • In a turret lathe , a longitudinally feed able, hexagon turret replaces the tail stock.

Advantages

  • Turret lathe is using to machine the long and heavy work pieces.
  • They having hexagonal tool post or head.
  • There is no need of changing  the tool.

Disadvantages

  • They have manual indexes.

6.SPECIAL PURPOSE LATHE 

  • Special Purpose lathe are using for special purposes and for jobs which cannot  be accommodated or conveniently machined on a standard lathe.

7.AUTOMATIC LATHE 

  • In the automatic lathe ,the various operations are automating like change of the work piece.
  • The working cycle is fully automatic that is repeated to produce duplicate parts without participation of operator.

Advantages 

  • During machine operation operator is free to operate another machine.
  • More economy in floor space.

Disadvantages

  • Lots of consideration are taking on fixing the setup.

LATHE ACCESSORIES 

  • Lathe accessories are generally divided into Two categories :-
  1. Work Holding device and 

  2.  Cutting Tool Holding device

   1. Work Holding device 

  • The work holding devices are  device which is using to hold and rotate the work pieces along with the spindle.
  •  The different work holding devices are using, according to the shape, length, diameter and weight of the work piece and the location of turning on the work. They are as follows :-

A. CHUCKS

  • A chuck is a specialized types of clamp used to hold the work piece.
  • Chuck is mounted on the spindle which rotates within the head stock.
    Three Jaw Chuck

  Types of chucks :

  1.  Three Jaw Chuck
  2.   Four  Jaw chuck
  3.   Collect Chuck
  4.    Spindle Chuck
  5.    Magnetic Chuck
  6.    Combination Chuck
  7.    Air Operated Chuck

B. FACE PLATE

Face Plate

  • Face plate is a circular disc and thread to fit to the nose of the lathe spindle.
  •  They having  radial plain and ‘T’ – slots for holding the work by bolts and clamps.

C.  MANDRELS 

Mandrel

  • Mandrel is a device which uses for holding a hollow work piece.
  • Mandrel is mounting between centers and work revolves with it .

D.  CENTERS

Live Center

  • A lathe center is a tool that has ground to a point to accurately position a work piece.
  • There are two centers :-
  1. Live center

  • A live center is a center which fits into the head stock spindle and revolves with the work.
  • A live center is constructed so that the 60 degree center runs in its own bearing .

      b. Dead center

  • Dead center is the center which uses a tail stock spindle and doesn’t revolve .

      c.  Half center

  •  Half center is the center which is often used in the tail stock  for facing up to or for Turning close to the end of the work .
  •  It cuts away almost to its point .

 E.   DRIVING PLATE OR CATCH PLATE

Driving Plate

  • Catch plate is plane disc which is made up of cast iron or steel .
  • They having a central

f. CARRIERS

Carrier

  •   Carrier is a device that Clamps around the work piece .
  •   They allow the rotary motion of the machines spindle to transmit  the work piece .
  •   There are two types of carrier :-

a. Straight Tail Carrier

  • This is using for driven the work by means of the pin provided in the driving plate .

b. Bent Tail Carrier

  • It fits into the slot of the catch plate to drive the work .

c . Angle Vise

Angle Vise lathe machine

  •   Angle vise is an angular adjustment on base to allow operator to drill holes at an angle without tilting table .

2. Cutting Tool Holding device

  • The cutting tool holding device is a device which is using to hold the cutting tools .
  • The different cutting tool holding devices are as follows:-

A. Tool Post

Tool Post lathe machine

  • Tool Post is a device which holds the cutting tool on a lathe and some other machine.

B. Collect

Collect

  • Collect is a device which is using to hold a cutting tool in the spindle of a milling machine.

C.  Drill Chucks

Drill Chuck lathe machine

  • It is the most common devices which are using for holding straight-shank cutting tools.
  • There are two common types:-

a.  Key Type

  • It  has loosened or tightened by key.

b.  Keys Less Types

  • It has loosened or tightened by hand without key.

D. Drill Sleeves

Drill Sleeve lathe machine

  • Drill sleeves are used to adapt smaller Morse taper shank tools to larger machine spindles.

E.  Drill Socket

Drill Socket lathe machine

 

  • Drill socket is used to hold twist drills with shanks.
  • They have used often an extension sockets.

F. Straight Tool Holders

Straight Tool Holder lathe machine

 

  • Straight is using for taken cuts in either direction and for general machining operations.

Specifications of Lathe

 1. a. Center distance

      b. Height of center

      c.Type of bed

2.  a. Swing in gap

      b. Gap in front of face place

      c. Swing over cross slide

      d. Swing over bed

3.  a. Spindle bore

      b. Spindle speed range

      c. Spindle nose

      d.Taper nose

4.  a. Longitudinal feeds

      b.Cross  feed

      c. Lead screw pitch

      d. Metric thread pitches

5.  a. Top slide travel

      b.Cross slide travel

      c.Tool section

6.  a.Taper in sleeve bore

      b.Tail stock  sleeve travel

7.  Motor horsepower in RPM ( Revolution per minute ).

8.  Shipping dimension 

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