18543038 Sand Casting Presentation

8/6/2019 18543038 Sand Casting Presentation

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SANDCASTING


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PRESENTED BY

GROUP 1ANG PHEI CHEE

CHUNG YU NING


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CONTENTS

INTRODUCTION

THE SAND

EQUIPMENTS GATING SYSTEM

THE PROCESS

FLOW CHART OF PROCESS CYCLE


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PRODUCTS OF SAND CASTING

cast model

bronze cast model


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INTRODUCTION

Sand casting, the most widely used casting

process, utilizes expendable sand moulds to

form complex metal parts that can be made of

nearly any alloy.

The sand casting process involves the use of a

furnace, metal, pattern, and sand mould.


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MATERIALS

Sand casting is able to make use of almost any alloy. An advantage of sandcasting is the ability to cast materials with high melting temperatures,including steel, nickel, and titanium.

The four most common materials that are used in sand casting are shownbelow, along with their melting temperatures.

Materials Melting temperature

Aluminum alloys 1220 F (660 C)

Brass alloys 1980 F (1082 C)

Cast iron1990-2300 F (1088-

1260 C)

Cast steel 2500 F (1371 C)


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ADVANTAGES

Can produce very large parts

Can form complex shapes

Many material options Low tooling and equipment cost

Scrap can be recycled

Short lead time possible


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DISADVANTAGES

Poor material strength

High porosity possible

Poor surface finish and tolerance Secondary machining often required

Low production rate

High labor cost


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THE SAND

Different types of sand are used in sand casting;

Petro-bond This is a mixture of quality sand andoil or synthetic resin.

Green sand A mixture of sand, clay, water andsometimes other additives. It is called green sandbecause it is re-usable. The right amount of waterhas to be added to prevent porosity.

Sand mixed with water glass can be hardened

with CO2 gas .(This transforms the sand into a solid mould, whichcan be used after the cope & drag are removed.)


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CHARACTERISTICS OF SAND

FLOWABILITY

The ability to pack tightly around the pattern.

PLASTIC DEFORMATION

Have the ability to deform slightly withoutcracking so that the pattern can be withdrawn.

GREEN STRENGTH

Have the ability to support its own weight whenstripped from the pattern, and also withstandpressure of molten metal when the mold is cast.


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PERMEABILITY

This allows the gases and steam to escapefrom the mold during casting.

THERMAL STABILTY

Ability to resist damage, such as cracking,from the heat of the molten metal.

REUSABILITY

Ability of the sand to be reused for futuresand molds.


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EQUIPMENTS

CASTING FLASK

Consists of the cope (top halve) and the drag

(bottom halve) to receive the pattern.

The drag (left) and cope

(right) of a casting flask


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PATTERN

Model of products, made of wood, plastic or

metals.

CORE

To produce cavities within the casting, made of

plaster, metals and ceramics.

Left:- Corebox, with resulting (wire reinforced)

cores directly below.

Right:- Pattern (used with the core) and

the resulting casting below

(the wires are from the remains of the core)


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STRAIGHT EDGE BAR

To level the sand above or below the casting flask,made of metals.

RAMMER

Consists of 2 different ends, an wedge-shaped end

and a flat shape end. Use to compress the sand.

PARTLING SAND

Put on the pattern to make it easier to remove.

LADLE

Use to melt the metals and pour into the mould.


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GATING SYSTEM

This picture shows the cross section of a sand casting mould.


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DEFINATIONS

POURING CUP

This is where the metal is poured into the mold.

SPRUE

The vertical channel from the top of the mold tothe gating and riser system. Also, a generic termused to cover all gates, runners and risers.

RUNNER The portion of the gate assembly that connectsthe sprue to the casting in gate or riser.


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GATE

The end of the runner in a mold where moltenmetal enters the mold cavity.

RISER

A reservoir of molten metal provided to

compensate for the contraction of the metal as it

solidifies.

MOLD CAVITY

The impression in a mold produced by theremoval of the pattern. When filled with molten

metal it forms a casting.


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COPE

Upper or top most section of a flask, mold orpattern.

PARTING LINE

A line on a pattern or casting corresponding to the

separation between the parts of a mold.

DRAG

Lower or bottom section of a flask, mold or

pattern.


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THE PROCESS


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A wooden pattern

of the required

casting shape ismade. A metal or

plastic can also be

used.


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A metal or

wooden flask isused to contain the

sand.


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The pattern is

placed in the flaskand packed in with

sand.


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The other half of

the mould is

placed on top,again staring with a

wooden or metal

frame.


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Sand is added

around the pattern

through a sieve, sothat it packs

together better.


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The sand is then

packed around the

pattern using thewedge-shaped end

of a rammer.


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More sand is

added, this timenot sieved.


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The sand is then

rammed in firmly

using a peen or theflat end of the

rammer.


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The sand is then

leveled off, and theexcess removed.


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A piece of pipe is

carefully pushed

through the sandto the pattern to

create a runner,

and some risers.


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Small holes arecreated in the

surface of the

sand, and CO2 gas

is passed throughto harden the

molding sand

mixed with the

water glass.


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The 2 halves of the

mould are thenseparated and the

pattern removed.


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The entrance to

the mould ( the

runner ) is then

connected to themould cavity, and

the other half

mould is hardened

with CO2.


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The 2 halves of the

mould are placed

back together,ready to make the

casting.


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Molten metal is

poured through

the runner until itfills the mould and

starts to flow up

the risers.


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The metal is left to

cool and solidify,

and then themould is broken

apart to reveal the

casting.


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The metal is left to

cool and solidify,

and then themould is broken

apart to reveal the

casting.


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The runner and

risers can then be

cut off, and thecasting polished to

give a better

surface finish.


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PROCESS CYCLE

MOULD

MAKINGCLAMPING POURING

COOLINGREMOVALTRIMMING


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PROCESS CYCLE


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THE END

Documents

18543038 Sand Casting Presentation