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Bulk Deformation - Introduction to Manufacturing Processes - Lecture Slides | ME 4563, Study notes of Mechanical Engineering

Arkansas State University (ASU) - Beebe Mechanical Engineering
Prof. Shivan Haran

Material Type: Notes; Professor: Haran; Class: INTRODUCTION TO MANUFACTURING PROCESSES; Subject: Mechanical Engineering; University: Arkansas State University; Term: Unknown 1989;

Typology: Study notes

Pre 2010

Uploaded on 09/17/2009

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ME 4563 Dr. S. Haran
College of Engineering
Arkansas State University
College of Engineering
College of Engineering
Arkansas State University
Arkansas State University
Introduction to Manufacturing
Processes
Introduction to Manufacturing
Introduction to Manufacturing
Processes
Processes
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ME 4563
ME 4563
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Download Bulk Deformation - Introduction to Manufacturing Processes - Lecture Slides | ME 4563 and more Study notes Mechanical Engineering in PDF only on Docsity!

ME 4563 Dr. S. Haran 1

College of Engineering Arkansas State University

College of EngineeringCollege of Engineering Arkansas State UniversityArkansas State University

Introduction to Manufacturing

Processes

Introduction to ManufacturingIntroduction to Manufacturing

ProcessesProcesses

ME 4563ME 4563ME 4563

ME 4563 Dr. S. Haran 2

Bulk Deformation Bulk Deformation

ME 4563 Dr. S. Haran 3

What isWhat is deformation processingdeformation processing??

  • • Process to make parts withoutProcess to make parts without

material removalmaterial removal

  • • Deformation occurs on parts with L/DDeformation occurs on parts with L/D

approx. equal to 1approx. equal to 1

DeformationDeformation

Example of products / Typical product dimensionsExample of products / Typical product dimensions ƒƒ Small: coins, surgical wire, etc.Small: coins, surgical wire, etc. ƒƒ^ Large: power plant turbine shafts, aircraft landingLarge: power plant turbine shafts, aircraft landing gear, etc.gear, etc.

ME 4563 Dr. S. Haran 4

““CastCast”” Structures are converted toStructures are converted to ““wroughtwrought”” structures through some means ofstructures through some means of deformationdeformation

  • • Normally starts with material that has been castNormally starts with material that has been cast (ingots, slabs, rods or pipes)(ingots, slabs, rods or pipes)
  • • Several different parts may be formedSeveral different parts may be formed
  • • The process involvesThe process involves ““heatheat”” (in most cases) and(in most cases) and ““forceforce”” to create the shapeto create the shape

DeformationDeformation

ME 4563 Dr. S. Haran 7

Temperature of deformationTemperature of deformation

  • • Hot workingHot working
  • •^ Cold workingCold working
  • • Warm workingWarm working

Purpose of DeformationPurpose of Deformation

  • •^ Primary ProcessesPrimary Processes
  • •^ Secondary ProcessesSecondary Processes

DeformationDeformation

Deformation process may be classifiedDeformation process may be classified

according to:according to:

ME 4563 Dr. S. Haran 8

DeformationDeformation

ME 4563 Dr. S. Haran 9

DeformationDeformation

Strain RateStrain Rate ‘‘^ ’:’:

Given by the ratio of theGiven by the ratio of the raterate at which the specimen isat which the specimen is pulled in tension or pushed in compression (v) to thepulled in tension or pushed in compression (v) to the instantaneous deformedinstantaneous deformed lengthlength (l)(l)

Low strain rates allow more time for atomic orLow strain rates allow more time for atomic or molecular rearrangement, leading to lower stressesmolecular rearrangement, leading to lower stresses and higher ductility.and higher ductility. Effected by TemperatureEffected by Temperature

Units?

ME 4563 Dr. S. Haran 10

Hot working:Hot working: Temperature of the work piece isTemperature of the work piece is highhigh (above(above ““room temperatureroom temperature””)) 600 600 ––1000 deg. C, depending upon metal/alloy1000 deg. C, depending upon metal/alloy

Advantages:Advantages: Flow stresses are low (lower forces & powerFlow stresses are low (lower forces & power requirements); very large pieces can be worked on;requirements); very large pieces can be worked on; ductility is highductility is high –– hence large deformations & complexhence large deformations & complex partsparts

Disadvantages:Disadvantages: Energy required to heat the piece; oxidizingEnergy required to heat the piece; oxidizing can impair surface finish; variations in finishingcan impair surface finish; variations in finishing temperatures lead to wide dimensional tolerancestemperatures lead to wide dimensional tolerances

DeformationDeformation

ME 4563 Dr. S. Haran 13

Purpose of DeformationPurpose of Deformation –– As aAs a Primary ProcessPrimary Process

  • • These aim to destroy the cast structure byThese aim to destroy the cast structure by successive deformation stepssuccessive deformation steps
  • • Results in a semiResults in a semi--fabricated product that will befabricated product that will be worked on furtherworked on further –– slabs, billets, platesslabs, billets, plates
  • • Conducted on large scale at speciallyConducted on large scale at specially constructed plantsconstructed plants

DeformationDeformation

ME 4563 Dr. S. Haran 14

Purpose of DeformationPurpose of Deformation –– As aAs a Secondary ProcessSecondary Process

  • • Take products of primary process and furtherTake products of primary process and further transform them into a finished parttransform them into a finished part –– bolts,bolts, metal parts, wires, rods, etc.metal parts, wires, rods, etc.
  • • Focus of all forging as well as other deformationFocus of all forging as well as other deformation processesprocesses

DeformationDeformation

ME 4563 Dr. S. Haran 15

  • •^ Involves a machine which causes gross orInvolves a machinewhich causes gross or

bulk deformation to provide a new shapebulk deformation to provide a new shape

  • •^ Can only use these processes when theCan only use these processes when the

material has amaterial hasa plastic regimeplastic regime in its stressin its stress

strain behavior.strain behavior.

  • •^ Most metalsMost metals
  • • Most plasticsMost plastics
  • •^ Some materials must be formed hotSome materials must beformed hot to obtainto obtain

plastic behaviorplastic behavior

DeformationDeformation

ME 4563 Dr. S. Haran 16

ElasticRegion

Stress

Strain

Non-Workhardening Region(This can be non-existent in some materials)

(this can be non-existentWork Hardening Region at high temperatures)

Necking

Failure

Uniform Elongation

EnergyMech Recovered

Mechanical Energy converted intoInternal energy plus heat All forming takes place in this region

Plastic Region:Permanent Deformation

Dislocations generated

Yield Stress

Onset of Necking

Typical stress-Typical stress- strain curvestrain curve

Region where materials can be worked

ME 4563 Dr. S. Haran 19

  • •^ Forging starts with a sawn off section of aForgingstarts with a sawn off section of a

cast or extruded ingot and ends up with acast or extruded ingot and ends up with a

multitude of shapes close to final formmultitude of shapes close to final form

  • • Least work required to make a useful productLeast work required to make a useful product

Bulk Deformation ProcessesBulk Deformation Processes

ME 4563 Dr. S. Haran 20

  • •^ ForgingForging
    • – Produces discrete parts with a variety of unlimitedProduces discrete parts with a variety of unlimited shapes;shapes;
    • – Typical properties better than extrusions;Typical properties better than extrusions;
    • – Surface finish fair to good; High die andSurface finish fair to good; High die and equipment costs; Moderate to high labor costs;equipment costs; Moderate to high labor costs; Moderate to high operator skillModerate to high operator skill

Characteristics of ProductsCharacteristics of Products

ME 4563 Dr. S. Haran 21

  • • Rolling typically starts with a rectangular ingotRollingtypically starts with a rectangular ingot

and results in various shapesand results in various shapes

  • – Plates (t > 6mm)Plates (t > 6mm)
  • – Rolls of thin sheet (t < 6mm)Rolls of thin sheet (t < 6mm)
  • – RodsRods
  • – BarsBars
  • – Structural shapes (IStructural shapes (I--Beams for e.g.)Beams for e.g.)
  • – RailsRails
  • •^ Typically, material must be further shaped orTypically, material must be further shaped or

formed to be usefulformed to be useful

Bulk Deformation ProcessesBulk Deformation Processes

ME 4563 Dr. S. Haran 22

  • •^ FlatFlat
    • – Produces coils of sheet and foil, rectangular flatProduces coils of sheet and foil, rectangular flat plate;plate;
    • – Excellent properties; Good surface finish; HighExcellent properties; Good surface finish; High capital investment; low labor costs; Skilled laborcapital investment; low labor costs; Skilled labor required to operate millrequired to operate mill
  • •^ ShapeShape
    • – Produces shapes of diverse cross section;Produces shapes of diverse cross section;
    • – Excellent properties along the rolling direction:Excellent properties along the rolling direction: Good surface finish; Expensive specially shapedGood surface finish; Expensive specially shaped rolls; Low labor costs; Relatively low labor skillrolls; Low labor costs; Relatively low labor skill required to operate millrequired to operate mill

Characteristics of ProductsCharacteristics of Products

ME 4563 Dr. S. Haran 25

  • • DrawingDrawing
    • – Produces long lengths of solid rod or wires ofProduces long lengths of solid rod or wires of constant cross section;constant cross section;
    • – Smaller cross sections than typical extrusion;Smaller cross sections than typical extrusion; Good surface finish; Low to moderate equipmentGood surface finish; Low to moderate equipment and labor costs; Low to moderate operator Skilland labor costs; Low to moderate operator Skill

Characteristics of ProductsCharacteristics of Products

ME 4563 Dr. S. Haran 26

Typical Formed and Shaped PartsTypical Formed and Shaped Parts in an Automobilein an Automobile

Ceramic Spark PlugCeramic Spark Plug

Stamped wheel coversStamped wheel covers

SpringsSprings

ColdCold--rolled sheet metalrolled sheet metal bodybody

Stamped platesStamped plates

Drawn tube for antennaDrawn tube for antenna

Forged ValvesForged Valves Molded dashboardMolded dashboard Shaped WindshieldShaped Windshield Molded tiresMolded tires Blow molded plasticBlow molded plastic tanks for fluidstanks for fluids Tail light lensesTail light lenses

From: Manufacturing Engineering & Technology – Kalpakjian and Schmid, 4Ed., 2001, Prentice-Hall th

Metal and plasticsMetal and plastics

ME 4563 Dr. S. Haran 27

Forging Forging

ME 4563 Dr. S. Haran 28

™™ Forging denotes a family of processes by whichForging denotes a family of processes by which plastic deformation of the workplastic deformation of the work--piece is carried out bypiece is carried out by compressive forces, at room temperature (cold), or atcompressive forces, at room temperature (cold), or at elevated temperatures (hot).elevated temperatures (hot).

™™^ Simple forging can be made with a heavy hammerSimple forging can be made with a heavy hammer and an anvil using techniques that have been availableand an anvil using techniques that have been available for centuries.for centuries.

™™ However, usually a set of dies and a press areHowever, usually a set of dies and a press are required.required.

ForgingForging

ME 4563 Dr. S. Haran 31

Advantages:Advantages:

  • • The grain flow, i.e., the directional pattern that metalThe grain flow, i.e., the directional pattern that metal crystals assume during plastic deformation, can be alignedcrystals assume during plastic deformation, can be aligned with the directions of the principal stresses that will occurwith the directions of the principal stresses that will occur when the work piece is loaded in service.when the work piece is loaded in service.
  • • Higher strength, ductility, and impact resistance areHigher strength, ductility, and impact resistance are achieved along the grain flow of the forged material than inachieved along the grain flow of the forged material than in the randomly oriented crystals of the cast metal or weldedthe randomly oriented crystals of the cast metal or welded metalmetal
  • • Structural integrity from piece to piece is better. GoodStructural integrity from piece to piece is better. Good quality forging control makes it easier to avoid internalquality forging control makes it easier to avoid internal pockets, voids, inclusions, laps, etc...pockets, voids, inclusions, laps, etc...

ForgingForging

ME 4563 Dr. S. Haran 32

A part made by three different processes, showing grain flow. (A part made by three different processes, showing grain flow. (a)a) casting, (b) machining, (c) forging.casting, (b) machining, (c) forging.^ SourceSource : Forging Industry: Forging Industry Association.Association.

From: Manufacturing Engineering & Technology – Kalpakjian and Schmid, 4Ed., 2001, Prentice-Hall th

ForgingForging

ME 4563 Dr. S. Haran 33

Disadvantages:Disadvantages:

  • • The forged parts often need to be machinedThe forged parts often need to be machined before usebefore use
  • • Forging tooling for complicated geometry mayForging tooling for complicated geometry may be expensive and require multiple passes onbe expensive and require multiple passes on the same work piecethe same work piece

ForgingForging

ME 4563 Dr. S. Haran 34

ƒƒ Material must have a good "Material must have a good"forgeabilityforgeability”” ƒƒ^ that can be shaped with low forces and withoutthat can be shaped with low forces and without cracking is said to have a goodcracking is said to have a good forgeabilityforgeability..

ƒƒ^ Forgeability competes with other properties andForgeabilitycompetes with other properties and geometry of thegeometry of the workpieceworkpiece: such as strength,: such as strength, corrosion resistance, toughness, fatiguecorrosion resistance, toughness, fatigue resistance,resistance,^ heat resistance, size and sectionheat resistance, size and section thickness.thickness.

ƒƒ^ Combined effects of temperature and deformationCombined effects of temperature and deformation change the properties of the material.change the properties of the material. ƒƒ^ Hence, helpful to know or predict how theHence, helpful to know or predict how the processprocess^ will alter the material propertieswill alter the material properties

Materials used in Forging Materials used in Forging

ME 4563 Dr. S. Haran 37

ForgingForging

ME 4563 Dr. S. Haran 38

ƒƒ Open DieOpen Die

ƒƒ Impression DieImpression Die

ƒƒ Closed DieClosed Die

ƒƒ^ Upset ForgingUpset Forging

ƒƒ^ Precision ForgingPrecision Forging

ƒƒ^ SwagingSwaging

ƒƒ^ Other VariationsOther Variations

Forging ProcessesForging Processes

ME 4563 Dr. S. Haran 39

Open Die Open Die

ForgingForging

ME 4563 Dr. S. Haran 40

ƒƒ^ It is the simplest form of forgingIt is the simplest form of forging

ƒƒ^ Involves placing a solid cylindrical work pieceInvolves placing a solid cylindrical work piece between two flat dies and reducing its height bybetween two flat dies and reducing its height by compressing it.compressing it.

ƒƒ^ The die surfaces can also be shaped; thereforeThe die surfaces can also be shaped; therefore forming the ends of the cylindrical work pieceforming the ends of the cylindrical work piece while compressing it.while compressing it.

Open Die ForgingOpen Die Forging