MAURBHANJ SCHOOL OF ENGINEERING

BARIPADA : 757107 , ODISHA

CHAPTER – 03

TOPIC- CASTING

BRANCH- MECH.

SEMISTER- 3^rd

SUBJECT- PRODUCTION TECHNOLOGY

FACULTY- ER KHAGESWAR PATRA

Estd:.1994

CONTENTS

• Casting process
• Types of casting processes
• Basic futures of casting
• Types of mould
• Types of permanent mold casting
• Advantages of permanent mold casting
• Limitations of permanent mold casting

CASTING PROCESS

• Casting is a manufacturing process by which the liquid material is usually poured into the mold , which contains a hollow cavity of the desired shape, and then allowed to solidify.
• The solidify part is also known as casting, which is ejected or broken out of the mould to complete the process.
• Casting materials are usually metals
• Almost all metals can be cast.
• Casting is most often used for making complex shapes that would be otherwise difficult to make by other methods.

TYPES OF CASTING PROCESS

• Sand casting process
• Die casting process
• Investment casting process
• Low pressure casting process
• Centrifugal casting process
• Gravity die casting process
• Vacume die casting process
• Seqeezing die casting process
• Lost foam casting process
• Continual casting process

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SAND CASTING PROCESS

• Sannd casting is casting method for producing casting in a sand molud
• Steel, iron, and other most non ferrous alloy casting can be obtained by sand casting process
• First making blank with complex shape with blank prepare cavity.
• It is adaptability and low cost
• Some materials with poor plasticity such as cast iron, so sand casting is only forming process for manufacturing its part or blank

BASIC FEATURES OF CASTING PROCESS

• Patterns : A pattern is made of wood or metal, is a replica of the final product and is used for preparing mould cavity.
• Riser: A column of metal placed in the mold to feed the casting as it shrinks and solidifies. Also known as q “feed head”.
• Runner: The chennel through which the molten metal is carried from the sprue to the gate.
• Cores: A separated part of the mould, made of sand and generally baked, which is used to create openings and various shaped cavities in the casting.

BASIC FEATURES OF CASTING PROCESS

• Gate: A chennel through which the molten metal enters the casting cavity.
• Parting Line : Joint where mold separates to permit removal of the pattern and which shows how and where to open the mold.
• Sand: A sand which binds strongly without losing it.
• Chaplet : A metal support used to hold a core in place in a mould. Not used when a core print will serve.

BASIC FEATURES OF CASTING PROCESS

• Binders: Materials used to hold molding and together.
• Pouring basin: Filling the mold with molten metal.
• Shrinkage: The decrease in volume when molten metal solidifies.
• Mould : The mould contains a cavity whose geometry determines the shape of cast part. Mould material should posses refractory characteristics and with stand the pouring temprature.

TYPES OF MOULDS

The various casting processes are classified according to these different moulds

• Open mould
• Closed mould

OPEN MOULD

• In which the liquid metal is simply poured until it fills the open cavity

CLOSED MOULD

• The closed mold is provided to permit the molten metal to flow from outside the mold cavity.
• The closed mold is more important categories in production casting operation.

PERMANENT MOULD CASTING

• In permanent mould casting process, the mould is refused many times.
• The molds are commonly made of steel or cast iron.
• The Metals commonly cast in the permanent mold casting includes alluminium, magnesium, and copper based alloys (brass, bronze).

TYPES OF PERMANENT MOULD CASTING

There are two types of permanent mold casting as under

• Die Casting
• Centrifugal Casting

DIE CASTING PROCESS

• Die casting is permanent mold casting process in which the molten metal is injected into mold cavity under high pressure, The pressure is maintained during solidification, after which the mold is opened and part is removed.
• Typical pressure are 7 to 350 mpa.
• The molds used in this casting operation is called dies ; hence the name die casting.

DIE CASTING MACHINES

There are two types of die casting machines that as under

• Hot chamber die casting
• Cold chamber die casting

HOT CHAMBER DIE CASTING

• In hot chamber die casting machines, the molten metal is poured into a heated chamber from an external melting container, and piston is used to inject the molten metal under a high pressure into die cavity.
• Typically injection pressure are 7 to 35 mpa
• This process is only used for the low melting point metals .( zinc, tin, and sometimes magnesium.)

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COLD CHAMBER DIE CASTING

• In which the molten metal poured into an unheated chamber, and piston is used to inject the liqued metal under a high pressure into the die cavity.
• Injection pressure used in these machine are typically 14 to 140 mpa.

CENTRIFUGAL CASTING

• In centrifugal casting the mold is rotated at high speed so that the centrifugal force is produced that distributes the molten metal to the outer regions of the cavity.
• Examples of parts made by this process includes Pipes, tubes, bushing and rings .

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ADVANTAGES OF PERMANENT MOLD CASTING

• High production rates possible
• Close toltarnce is possible for small parts.
• Good surface finish
• Thin sections are possible.
• Rapid solidification.

LIMITATIONS OF PERMANENT MOLD CASTING

• Only used for low melting point metals
• More intricate shapes are not achieved.
• Mold is expensive.

Thank you

CREATED BY : ER KHAGESWAR PATRA