MANUFACTURINGMANUFACTURING(Lecture 2)

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Manufacturing ProcessesManufacturing Processes Processes add value to materialsProcesses add value to materials A process involves a number of steps or operationsA process involves a number of steps or operations Four basic processes applied on production materials are Four basic processes applied on production materials are

forming, material removal, assembly (or joining) and forming, material removal, assembly (or joining) and conditioningconditioning

Forming Forming operations change the geometry of the starting operations change the geometry of the starting material without cutting itmaterial without cutting it

Material removalMaterial removal or separating processes remove a part or separating processes remove a part of the starting material using a tool to get the desired of the starting material using a tool to get the desired geometrygeometry

Combining Combining processes join two materials or deposit processes join two materials or deposit material onto the exterior surface of the starting materialmaterial onto the exterior surface of the starting material

ConditioningConditioning processes add value to the starting material processes add value to the starting material by improving its internal and physical propertiesby improving its internal and physical properties

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Forming ProcessesForming Processes CastingCasting

– A material in a liquid or semisolid form is poured or forced to flow A material in a liquid or semisolid form is poured or forced to flow into a mold cavity and allowed to solidify, thus taking the solid into a mold cavity and allowed to solidify, thus taking the solid shape of the cavityshape of the cavity

– The process can be applied on metals, ceramics and plasticsThe process can be applied on metals, ceramics and plastics– The term casting is commonly used for metalsThe term casting is commonly used for metals– The term molding is used for plasticsThe term molding is used for plastics– Examples of molds – cake-pan, an ice-cube-tray or the footprints on Examples of molds – cake-pan, an ice-cube-tray or the footprints on

a beacha beach– Types of castings – sand casting and die castingTypes of castings – sand casting and die casting– Sand castingSand casting – pouring molten metal into a sand mold, breaking up – pouring molten metal into a sand mold, breaking up

the mold to remove the castingthe mold to remove the casting– Sand casting requires a Sand casting requires a patternpattern – a full sized model of the part – a full sized model of the part – Die castingDie casting is a permanent-mold-casting – molten metal is injected is a permanent-mold-casting – molten metal is injected

into the mold cavity under high pressureinto the mold cavity under high pressure– Molds for die casting are named as Molds for die casting are named as diesdies

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Forming ProcessesForming Processes

PressingPressing– Pressing is commonly used for majority of sheet metal parts of an Pressing is commonly used for majority of sheet metal parts of an

automobileautomobile– A measured amount of material is poured into a mold. A plunger with its A measured amount of material is poured into a mold. A plunger with its

own shape is lowered to force the material to spread out and fill the own shape is lowered to force the material to spread out and fill the moldmold

– The material is forced into the shape of the mold at the bottom and the The material is forced into the shape of the mold at the bottom and the shape of the plunger at the topshape of the plunger at the top

– Mechanical or hydraulic presses are usedMechanical or hydraulic presses are used– The plunger and the base of a forming die transform the sheet metal The plunger and the base of a forming die transform the sheet metal

into the required shape – into the required shape – drawingdrawing – fuel tank of a motorbike – fuel tank of a motorbike

Casting with a two-piece mold

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Forming ProcessesForming Processes PressingPressing

– RollingRolling is a type of pressing – thickness of the starting material is is a type of pressing – thickness of the starting material is reduced by compressive forces exerted by two opposing rolls reduced by compressive forces exerted by two opposing rolls

– Great pressure can make the powdered metal into a solid. The Great pressure can make the powdered metal into a solid. The material is then heated to make the object hard – material is then heated to make the object hard – sinteringsintering

Some parts of an automobile that are made through pressing

Fenders Bumpers Trunk Lids Doors Hoods

Rolling of a slab

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Forming ProcessesForming Processes ForgingForging

– The oldest metal forming operationThe oldest metal forming operation– Work part is heated and compressed using either impact or Work part is heated and compressed using either impact or

gradual pressure partgradual pressure part– Forging machine applying an impact load – Forging machine applying an impact load – forging hammerforging hammer– Forging machine applying gradual pressure – Forging machine applying gradual pressure – forging pressforging press– Examples – high-strength components for automotive and aircrafts Examples – high-strength components for automotive and aircrafts

like engine crank shafts and connecting rods, gears, aircraft like engine crank shafts and connecting rods, gears, aircraft structural components, and jet engine turbine partsstructural components, and jet engine turbine parts

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Forming ProcessesForming Processes ExtrusionExtrusion

– A compression process in which the work metal is forced to flow A compression process in which the work metal is forced to flow through a die opening, thereby taking the shape of the opening as through a die opening, thereby taking the shape of the opening as its own cross-sectionits own cross-section

– Toothpaste is a very good example of the processToothpaste is a very good example of the process– Different shapes are possible especially with hot extrusionDifferent shapes are possible especially with hot extrusion– The end product does not require much more shaping and The end product does not require much more shaping and

machiningmachining

Extruding a red hot metal

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Forming ProcessesForming Processes Blow MoldingBlow Molding

– Air pressure is used to inflate soft plastic into a mold cavityAir pressure is used to inflate soft plastic into a mold cavity– One-piece hollow plastic parts with thin walls are possible, such as One-piece hollow plastic parts with thin walls are possible, such as

bottles and similar containersbottles and similar containers– The technology is borrowed from the glass industry with which The technology is borrowed from the glass industry with which

plastics compete in the disposable or recyclable bottle marketplastics compete in the disposable or recyclable bottle market

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Material Removal ProcessesMaterial Removal Processes Operations that remove excess material from the starting Operations that remove excess material from the starting

workpiece to get the desired geometryworkpiece to get the desired geometry Use of knives and scissors is a common exampleUse of knives and scissors is a common example Important processes – shearing, sawing and machining Important processes – shearing, sawing and machining

operations such as turning, drilling and milling, shaping and operations such as turning, drilling and milling, shaping and planing and grindingplaning and grinding

Nontraditional processes – lasers, filters, magnets and Nontraditional processes – lasers, filters, magnets and electrochemical energyelectrochemical energy

SawingSawing– A narrow slit is cut into the workpiece by a tool consisting of a series A narrow slit is cut into the workpiece by a tool consisting of a series

of narrowly spaced teeth of narrowly spaced teeth – Most sawing operations – work is held stationary and saw blade is Most sawing operations – work is held stationary and saw blade is

moved relative to itmoved relative to it– Types – hacksawing and bandsawingTypes – hacksawing and bandsawing– Hacksaw blade – thin straight tool with cutting teeth on one edgeHacksaw blade – thin straight tool with cutting teeth on one edge– Bandsaw blade – endless flexible loop with teeth on one edge – pulley-Bandsaw blade – endless flexible loop with teeth on one edge – pulley-

like drive mechanismlike drive mechanism

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Material Removal ProcessesMaterial Removal Processes

SawingSawing

A power hacksaw

A vertical bandsaw

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Material Removal ProcessesMaterial Removal Processes ShearingShearing

– Metal cutting operation along a straight line between two cutting Metal cutting operation along a straight line between two cutting edges – similar to using a pair of scissorsedges – similar to using a pair of scissors

– Typically used to cut large sheets into smaller sections for Typically used to cut large sheets into smaller sections for subsequent pressworking operationssubsequent pressworking operations

– Other similar processes are blanking and punchingOther similar processes are blanking and punching

Shearing Blanking and punching

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Material Removal ProcessesMaterial Removal Processes TurningTurning

– Cutting tool with a single cutting edge – rotating workpiece to Cutting tool with a single cutting edge – rotating workpiece to generate a cylindrical shapegenerate a cylindrical shape

– Turning is commonly performed using a latheTurning is commonly performed using a lathe

DrillingDrilling– Used to create a round holeUsed to create a round hole– A rotating tool that has two cutting edgesA rotating tool that has two cutting edges– The holes can be made from 1/10,000 of an inch to 3½ inchesThe holes can be made from 1/10,000 of an inch to 3½ inches

MillingMilling– Rotating tool with multiple cutting edges – plane or straight Rotating tool with multiple cutting edges – plane or straight

surface surface – Types – vertical milling and horizontal or face milling Types – vertical milling and horizontal or face milling

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Material Removal ProcessesMaterial Removal Processes Shaping and PlaningShaping and Planing

– Single-point cutting tool moved linearly relative to the workpieceSingle-point cutting tool moved linearly relative to the workpiece– Creating a straight, flat surface Creating a straight, flat surface – Shaping – tool provides the speed motion and the workpiece remains Shaping – tool provides the speed motion and the workpiece remains

staticstatic– Planing – workpiece provides the speed motion while the tool remains Planing – workpiece provides the speed motion while the tool remains

motionless. motionless. GrindingGrinding

– Used to provide surface finish and the uniform thickness of the workpieceUsed to provide surface finish and the uniform thickness of the workpiece– Abrasive particles are used – sand paper or grinding wheelAbrasive particles are used – sand paper or grinding wheel– Abrasives – very small crushed particles of hard materials like aluminum Abrasives – very small crushed particles of hard materials like aluminum

oxide and silicon carbideoxide and silicon carbide– Grinding wheel – usually disk-shaped, precisely balanced for high Grinding wheel – usually disk-shaped, precisely balanced for high

rotational speedsrotational speeds– Common forms of grinding – polishing, buffing and the use of toothpasteCommon forms of grinding – polishing, buffing and the use of toothpaste

Grinding tools

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Assembly ProcessesAssembly Processes Two or more separate parts are joined to form a new entityTwo or more separate parts are joined to form a new entity Components are connected – permanently or semi permanentlyComponents are connected – permanently or semi permanently Types – mechanical methods, thermal methods and adhesive Types – mechanical methods, thermal methods and adhesive

bonding bonding Mechanical AssemblyMechanical Assembly

– Various fastening methods – use of hardware components, called fastenersVarious fastening methods – use of hardware components, called fasteners– Products using mechanical assembly – automobiles, large and small Products using mechanical assembly – automobiles, large and small

appliances, telephones, furniture, utensils and wearing apparelsappliances, telephones, furniture, utensils and wearing apparels– Categories – nails, threaded fasteners and rivets Categories – nails, threaded fasteners and rivets – Mechanical assembly is often preferred for its ease of assembly and Mechanical assembly is often preferred for its ease of assembly and

disassemblydisassembly– NailsNails are commonly used for wood – finishing nails, box nails and common are commonly used for wood – finishing nails, box nails and common

nailsnails