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Green Sand moulding

1



Classification of moulding sands

According to their use in the foundry, moulding sands areclassied into following categories:

1. Green sand:

The term " green sand " is known principally because of the

moisture content within the sand. The sand undergoes a

" mulling" process in which various clay and chemical

additives that act as binders are blended with the sand,

which results in a compound which is suitable for the sand

moulding process.



It is sand used in the wet condition for making the

mould. It is mixture of silica sand with 15-25 per cent

clay and 6-8 per cent water.

Green sand moulds are not dried and metal is poured

in them in the wet condition.

eing damp the sand can !e easily worked with handto gi"e it any desired shape.

#his sand is used for producing small to medium

si$ed moulds which are not "ery complex.



2. %ry sand&

%ry sand is the green sand that has !een dried or!aked after preparing the mould.

%rying sand gi"es strength to the mould so that it

can !e used for larger castings.

http://www.mechanicalengineeringblog.com/wp-content/uploads/2012/01/01-baked-sand-dry-sand1.jpg



'. (oam sand&

(oam sand is sand containing up to 5) *clay which has !een worked to the

consistency of !uilder mortar.

#his sand is used for loam sand moulds formaking "ery hea"y castings usually with the

help of sweeps and skeleton patterns.

http://www.mechanicalengineeringblog.com/wp-content/uploads/2012/01/01-loam-sand-with-50-clay.jpg



+. ,arting sand&

#his sand is used during making of the mould toensure that green sand does not stick to the pattern

and the cope and drag parts can !e easily separated

for remo"ing the pattern without causing any damage

to the mould.

http://www.mechanicalengineeringblog.com/wp-content/uploads/2012/01/01-parting-sand-dried-silica-sand-powder-sand.jpg



5. acing sand&

acing sand is the sand which co"ers the pattern all around it. #he remaining !ox is

filled with ordinary floor sand.

acing sand forms the face of the mould andcomes in direct contact with the molten metal

when it is poured.

http://www.mechanicalengineeringblog.com/wp-content/uploads/2012/01/01-facing-sand-silica-sand-with-clay.jpg



6. acking sand&

acking sand is the !ulk of the sand used to!ack up the facing sand and to fill up the

"olume of the flask.

#he main purpose for the use of !acking sandis to reduce the cost of moulding.

http://www.mechanicalengineeringblog.com/wp-content/uploads/2012/01/01-gate-cutter-mold-cavity-cutter-mould-tool.jpg



. /ystem sand&

#his is the sand used in mechani$edfoundries for filling the entire flask.

/and0 cleaned and reacti"ated !y the addition of

water and !inders is used to fill the flask. ecauseof the a!sence of any fresh sand0 system sand

must ha"e more strength0 permea!ility and

refractoriness compared to !acking sand.

http://www.mechanicalengineeringblog.com/wp-content/uploads/2012/01/01-system-sand-used-sand-sand-after-casting-process-over1.jpg



8. ore sand&

ore sand is the sand used for making cores.#his is silica sand mixed with core oil. #hat is

why it is also called oil sand.

http://www.mechanicalengineeringblog.com/wp-content/uploads/2012/01/01-core-sand-sand-core-silica-sand-mixed-with-core-oil-sodium-silicate-sand1.jpg



Green sand moulding process

Green sand moulding is more wide de"elop

than any other process.

Green sand moulding is replacing many ofthe more expensi"e moulding methods as

sand control is !eing

applied.



hy we use Green sandmoulding process 3

-4easona!le cost.

-n"ironmental friendly.

-igh producti"ity 7conomical.

-asily adapta!le to manual 0 semi-auto and

automatic moulding 9achines.



,roperties

1 Green sand for moulding must fulfill

and pack tightly round the pattern under

pressure. It must !e :lowa!le;.

2 Green sand for moulding should !e

a!le of !eing deformed slightly without

cracking0 so that the pattern can !ewithdrawn. In other words0 it must

exhi!it :,lastic; !eha"ior.



' Green sand must ha"e sufficient strengthto strip from the patterns and support its

own weight without deforming0 and

withstand the pressure of molten metal when

the mould is cast. It must therefore get:Green /trength;.

+ Green sand should !e :,ermea!le; 0 so

gases and steam can escape from the mouldat the !eginning of pouring to a"oid any kind

of defects.



5 Green sand must get :%ry /trength; to pre"ent erosion !y li<uid metal during

pouring as the mould surface dries out.

6 Green sand must guarantee a good

:4efractoriness; to withstand the high

temperature in"ol"ed without melting or

fusing with the metal.



16

Background: SAND-CASTING

Sand,

mixed with clay binder &

water (so it will hold its

shape) plus coal dust to

improe sur!a"e !i#ish

Pattern(a "op$ o! the shape

$ou wa#t to produ"e%

made o! wood% plasti"

or metal)

Basic materials & equipment for green sand-casting

Co#tai#er o! molten metal(!illed !rom !ur#a"e) Top a#d ottom mold forms

(made o! metal% ope# at top a#d ottom)

Rammer (tool to "ompa"t the sa#d'

o!te# a pressi# ma"hi#e is used)



1

Background: *hat is a +ou#dr$,

Casting is one of te oldest industrial processes

!ere are different casting processes"

!e focus ere is# $GR%% S'() C'S!*G

' foundry is#

a factory tat pours molten metal into

molds, producing cast metal ob+ects"

Sometypical

cast metal

ob+ects#“low tech” “high tech”

!urbine bladesin +et engines

%ngine blocks,

ales

'luminum

pots



1


moulding:

Sa#d pla"ed

i#to ottom

mold !orm &

"ompa"ted

moulding#

.atter# pla"ed i#to mold

A er$ asi" summar$ o! the sa#d "asti# pro"ess/ / /

+irst o! all%

mi te sand"

01!%



1


moulding# Add

the top mold

!orm

2

3 moulding# +ill top !orm

with "ompa"ted sa#d/

A tue or pipe

proides a path to

pour the metal i#

.atter# is still i#side4



05


moulding#

Tae the top

mold o!! a#d

remoe patter#

& pipe or post

7

6 moulding# 8epla"e the

top mold a#d !aste#

se"urel$4

.ouri#

hole

I# the middle o! thesa#d is a "ait$

shaped lie the

patter#4



01


C'S!*G#

.our the metal ("o#tai#er is

!illed !rom !ur#a"e immediatel$

e!ore $ou are read$ to pour)

*ait !or the metal to "ool

(mi#utes to da$s%

depe#di# o# the si9e o!

the "asti#)



00


S'.% /0!# rea apart the two

hales o! the mold & tae out the

part;usuall$ re<uires irati# or

strii# the mold to rea apart

the sa#d

C1%'*G" Sa#d is

"lea#ed o!! the part% the

=ta> where metal !lowed

i# must e remoed/

A "op$ o! the

patter# has #ow

ee# made i# metal

15 2old forms are reused

11Sand is roe# up%

s"ree#ed to remoe

deris a#d "lumps% a#d

se#t !or remixi#



02


Sa#d-"asti# is

simple i# "o#"ept% ut

dema#di# i#exe"utio#/ It is a

pro"ess esse#tial to

mai# asi" a#d

ada#"ed produ"ts/ / /it is also ha9ardous

a#d e#er$-i#te#sie4



03

3oundry process map

Sand (new/old),bentonite*, coal dust,

water, energy

liquid metal

moulding

Section

Dust, gases, mold

forms, used sand

Dust, gases, noise,reject mixed sand,surplus sand

Dust, gases, surplussand, noise, rejected

molds

Energy

ases, organicfumes

!atterns, mold forms,sand "lling, coatings,

energy

*Bentonite is a mineral clay.

It forms a binding agentwhen mixed with water.

Sand miing

area

moulding

section

Casting area

Sake-out &

Cleaning area

#$!%&S$on'!roduct

%&!%&S3inised

products



Pattern

07



3unctions of pattern

2oulding te Gating system4

%stablising a parting 1ine,

2aking Cores, 2inimising casting (efects,

Pro5iding %conomy in moulding

/ters, as needed



(ifferent types of patterns#

!e common types of patterns are#

67 Single piece pattern

87 Split piece pattern

97 1oose piece pattern

:7 Gated pattern

;7 2atc pattern

<7 Sweep pattern=7 Cope and drag pattern

>7 Skeleton pattern

?7 Sell pattern

6@7 3ollow board pattern

0



0

Single piece pattern:

This is the simplest type of pattern, exactly like thedesired casting. For making a mould, the pattern is

accommodated either in cope or drag.

Used for producing a few large castings, for example,

stuffing box of steam engine.



0

Split pattern:

These patterns are split along the parting plane(which may be flat or irregular surface) to facilitate

the extraction of the patternout of the mould before

the pouring operation. For a more complex casting,

the pattern may be split in more than two parts.



25

Loose piece pattern:

When a one piece solid pattern has projections or backdrafts which lie above or below the parting plane, it is

impossible to with draw it from the mould. With

such patterns, the projections are made with the help of

loose pieces. One drawback of loose feces is that their

shifting is possible during ramming.



21

Gated pattern:

A gated pattern is simply one or more loose patterns

having attached gates and runners.Because of their higher cost, these patterns are used

for producing small castings in mass production

systems and on molding machines.



20

Match plate pattern:

A match plate pattern is a split pattern having the cope and

drags portions mounted on opposite sides of a plate (usuallymetallic), called the "match plate" that conforms to the

contour of the parting surface.

The gates and runners are also mounted on the match plate, so

that very little hand work is required. This results in higherproductivity. This type of pattern is used for a large number of

castings.

Piston rings of I.C. engines are produced by this process.



22

Sweep pattern:

A sweep is a section or board (wooden) of propercontour that is rotated about one edge to shape mould

cavities having shapes of rotational symmetry. This type

of pattern is used when a casting of large size is to be

produced in a short time. Large kettles of C.I. are made

by sweep patterns.



23

Cope and drag pattern:

A cope and drag pattern is a split pattern havingthecope and drag portions each mounted on

separate match plates. These patterns are used

when in the production of large castings; the

complete moulds are too heavy and unwieldy tobe handled by a single worker.



27

Skeleton pattern:

For large castings having simple geometrical shapes,skeleton patterns are used. Just like sweep patterns, these

are simple wooden frames that outline the shape of

the part to be cast and are also used as guides by the

molder in the hand shaping of the mould.This type of pattern is also used in pit or floor molding

process.



26

Follow board pattern:

A follow board is not a pattern but is adevice (wooden board) used for

various purposes.



Sell mpulding

2

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