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PRESENTATION ON LATHE MACHINE PRINCIPLE OF LATHELathe is a machine, which is used to remove metal from the workpiece to required shape and size. COMPONENTS OF LATHE

TYPES OF LATHESSpeed Lathe :It is the simplest type lathe. It is mainly used for metal spinning, polishing etc.Bench Lathe :It is small sized engine lathe mounted on bench. It is used for turning small and light weight workpiece.Tool Room Lathe :It is used for production of small tools, gauges, fixtures and accurate parts in tool room.

Turret Lathe :These lathes are used in mass production and for heavy duty workpieces.Capsten Lathe :These lathes are used in mass production used for light duty workpieces.Special Purpose Lathe :These lathes are modification of engine lathes developed for machining special types of workpices.

Automatic Lathe Engine LatheTracer LatheComputer Controlled latheSwiss Type Automatic LatheDuplicating Lathe

COMPUTER NUMERICALLY CONTROLLED LATHE

Computer Numerical Controls (CNC)Equipped with one or more turretsEach turret is equipped with a variety of toolsPerforms several operations on different surfaces of the workpiece

TURRET LATHECapable of performing multiple cutting operations on the same workpieceTurningBoringDrillingThread cuttingFacingTurret lathes are very versatileTypes of turret lathesRam-type: ram slides in a separate base on the saddleSaddle type: more heavily constructedUsed to machine large workpeiceces

ENGINE LATHE

BENCH LATHE

AUTOMATIC LATHEPARTS OF LATHE

Bed : Supports all major componentsCarriage: Slides along the ways and consists of the cross-slide, tool post, apronHeadstock : Holds the jaws for the work piece, supplies power to the jaws and has various drive speedsTailstock : Supports the other end of the workpieceFeed Rod and Lead Screw : Feed rod is powered by a set of gears from the headstockLATHE BED

Heavy, rugged castingMade to support working parts of latheOn top section are machined waysGuide and align major parts of latheHEADSTOCK

Clamped on left-hand end of bedHeadstock spindleHollow cylindrical shaft supported by bearingsProvides drive through gears to work-holding devices

CARRIAGEUsed to move cutting tool along lathe bedConsists of three main partsSaddleCross-slideApron

APRON16

TAILSTOCKACCESSORIESChucks :Three jaw chuckFour jaw chuckCollet chuckCentres:Live centreDead centreTipped centreBall centreMandrels :Plain mandrelStepped mandrelCollared mandrelScrewed mandrel

Chucks :Three Jaw Chuck (Self Centering Chuck) : This chuck is used to hold circular workpiece and is available in sizes from 100mm to 600 mm.Four Jaw Chuck (Independent Chuck) :It is used to hold rectangular, sqare and irregular shaped workpieces .

ACCESSORIESCollet Chuck :Pull poerating rodPush poerating rod It is ideal for holding tube and thin walled workpieces.

Centres:Live CentreDead CentreBall CentrePipe CentreHalf CentreTipped Centre

Mandrels :Plain MandrelCollared MandrelScrewed MnadrelStepped Mandrel

LATHE OPERATIONS

Turing FacingBoringDrillingTaperCamferingGroovingFormingReamingUndercuttingThread cuttingKnurlingLATHE OPERATIONSBORING

Boring produces circular internal profiles in hollow workpiecesBoring mills are used for large workpiecesHoles can be bored up to 20M if neededSee fig. 22.20Machines are available with a variety of featuresHorizontal boring machinesJig borersTURNINGForces in turning Cutting force: acts downward on the tool tipThrust force: acts in the longitudinal directionRadial force: acts in the radial direction

Roughing and Finishing CutsRough cut: high speed cut with little regard for dimensional toleranceFinishing cut: lower feed rate and depth of cutTool Materials, Feeds, and Cutting SpeedsCutting Fluids

CONCEPT OF SPEED, FEED AND DEPTH OF CUT

Cutting speed=dn mm/min 1000Feed :It is expressed in mm/revDepth of cut :t=D-d mm 2

SINGLE POINT CUTTING TOOL GEOMETRY

ClearanceRakeEnd cutting edge angleSide cutting edge angle