1CASTING PROCESS - 1

Assoc Prof Zainal Abidin AhmadUniversiti Teknologi Malaysia

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Outline

Overview of casting technology What is casting Brief history of casting Advantages & disadvantages of casting Products made by casting Casting Classifications Casting Foundries

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Classification of Manufacturing Processes

Process

Casting

Machining/Cutting

Forming

Assembly/Joining

Permanent Mould Permanent Pattern Expendable mould &

Pattern

Electro-machining Mechanical Machining

Sheet Bulk Powder

Fusion welding Solid state welding Adhesive bonding Mechanical fastening

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What is Casting?

Process in which molten metal flows by gravity or other force into a mold where it solidifies in the shape of the mold cavity

The term casting also applies to the part made in the process

Steps in casting seem simple: 1. Melt the metal2. Pour it into a mold3. Let it freeze4. Break-up or open mold and remove casting

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What is Casting?Melt material

Pour into Mouldand allow to solidify

Break up mould and remove casting

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CASTING Referring to the process

or the product

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Capabilities and Advantages of Casting

Can create complex part geometries Can create both external and internal shapes Some casting processes are net shape; others

are near net shape Can produce very large parts Some casting methods are suited to mass

production

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Disadvantages of Casting

Different disadvantages for different casting processes: Limitations on mechanical properties Poor dimensional accuracy and surface finish for

some processes; e.g., sand casting Safety hazards to workers due to hot molten metals Environmental problems

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Parts Made by Casting

Big parts: engine blocks and heads for automotive vehicles, wood burning stoves, machine frames, railway wheels, pipes, church bells, big statues, and pump housings

Small parts: dental crowns, jewelry, small statues, and frying pans

All varieties of metals can be cast, ferrous and nonferrous

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Parts Made by Casting

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Parts Made by Casting

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Parts Made by Casting

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Parts Made by Casting

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Parts Made by Casting

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Parts Made by Casting

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Parts Made by Casting

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Parts Made by Casting

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Parts Made by Casting

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Parts Made by Casting

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Parts Made by Casting

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Parts Made by Casting

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Parts Made by Casting

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Parts Made by Casting

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Two Categories of Casting Process

1. Expendable mold processes uses an expendable mold which must be destroyed to remove casting Mold materials: sand, plaster, and similar materials,

plus binders2. Permanent mold processes uses a permanent

mold which can be used many times to produce many castings Made of metal (or, less commonly, a ceramic

refractory material

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Casting ProcessesPermanent mould

Continuous castingGravity die castingSqueeze castingCentrifugal castingReaction injection mouldingInjection mouldingCompression mouldingRotational moulding

Permanent pattern Sand Casting Shell moulding

Expendable mould & pattern

Investment Casting Ceramic/plaster

mould casting Full mould

evaporative pattern casting

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Advantages and Disadvantages

More intricate geometries are possible with expendable mold processes

Part shapes in permanent mold processes are limited by the need to open mold

Permanent mold processes are more economic in high production operations

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