CASTING PROCESS Jitendra Pathak

8/13/2019 CASTING PROCESS Jitendra Pathak

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CASTING PROCESS(WIDE VIEW ON SAND CSTING)

MATERIAL SCIENCE

(METAL)

PREPARED BY:JITENDRA PATHAK

ROLL- 9

FP-TECHGUIDED BY:

CHAKRAPANI

SIR


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WHAT IS CASTING??????????

Castingis a manufacturing process by which a liquid material is

usually poured into a mold, which contains a hollow cavity of

the desired shape, and then allowed to solidify. The solidified

part is also known as a casting, which is ejected or broken out of

the mold to complete the process. Casting materials are usually

metals or various cold settingmaterials that cure after mixingtwo or more components together; examples

are epoxy, concrete, plaster and clay. Casting is most often used

for making complex shapes that would be otherwise difficult or

uneconomical to make by other methods.Casting is a 6000 year old process. The oldest surviving casting is

a copper frog from 3200 BC.


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Casting since about 4000 BC

Ancient Greece; bronze

statue casting circa 450BC

Iron works in early Europe,

e.g. cast iron cannons from

England circa 1543


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Casting Methods

Sand CastingHigh Temperature Alloy,

Complex Geometry, Rough

Surface Finish

Investment CastingHigh Temperature Alloy, Complex

Geometry, Moderately Smooth

Surface Finish

Die CastingHigh Temperature Alloy,

Moderate Geometry,

Smooth Surface


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Basic Features

Pattern and Mould

A pattern is made of wood or metal, is a replica of thefinal product and is used for preparing mould cavity

Mould cavity which contains molten metal isessentially a negative of the final product

Mould material should posses refractorycharacteristics and with stand the pouringtemperature

When the mold is used for single casting, it made ofsand and known as expendable mold

When the mold is used repeatedly for number ofcastings and is made of metal or graphite are calledpermanent mould

For making holes or hollow cavities inside a casting,cores made of either sand or metal are used.


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Melting and Pouring

Several types of furnaces are available for meltingmetals and their selection depends on the type ofmetal, the maximum temperature required and therate and the mode of molten metal delivery.

Before pouring provisions are made for the escape ofdissolved gases. The gating system should be designedto minimize the turbulent flow and erosion of mouldcavity.The other important factors are the pouring

temperature and the pouring rate.


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Removal, Cleaning, Finishing and Inspection

After the casting is removed from the mould it is thoroughly

cleaned and the excess material usually along the parting line

and the place where the molten metal was poured, is removed

using a potable grinder.

White light inspection, pressure test, magnetic particle

inspection, radiographic test, ultrasonic inspection etc. are used


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Classification of casting processes


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Sand CastingDescription: Tempered sand is packed into wood or metal pattern halves, removed

form the pattern, and assembled with or without cores, and metal is poured into

resultant cavities. Various core materials can be used. Molds are broken to removecastings. Specialized binders now in use can improve tolerances and surface finish.

Metals: Most castable metals.

Size Range: Limitation depends on foundry capabilities. Ounces to many tons.

Tolerances:

Non-Ferrous1/32to 6

Add .003to 3, 3/64from 3to 6.

Across parting line add .020to .090depending on size. (Assumes metal patterns)

Surface Finish:

Non-Ferrous: 150-350 RMS

Ferrous: 300-700RMS

Minimum Draft Requirements:

1to 5

Cores: 1

to 1 1/2

Normal Minimum Section Thickness:

Non-Ferrous: 1/8- 1/4

Ferrous: 1/4- 3/8

Ordering Quantities: All quantities

Normal Lead Time:

Samples: 2-10 weeks

Production 2-4 weeks A.S.A.


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Sand Casting Mold Features

Vents, which are placed in molds to

carry off gases produced when the

molten metal comes into contact

with the sand in the molds andcore. They also exhaust air from

the mold cavity as the molten

metal flows into the mold.


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Pattern geometry


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Production steps in sand casting including pattern

making and mold making


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Shrinkage defects

Gas porosity

DEFECTS

Pouring metal defects

Metallurgical defects


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Documents

CASTING PROCESS Jitendra Pathak