FOUNDRY FORGING AND WELDING LABORATORY 2022 PART A.pdf

FOUNDRY, FORGING & WELDING LAB (18MEL38B/48B), by – Dr. S B MALLUR, Professor, UBDTCE, Davanagere 1
Mechanical Engineering Department
University B.D.T College of Engineering, Davangere
(A Constituent College of V.T.U, Belgaum)
LAB MANUAL
III/IV Semester
FOUNDRY, FORGING AND WELDING
LABORATORY
(18MEL38B/48B)
Name:_________________________________________
U.S.N:_________________________________________
Batch:________________ Section:________________
Dr. S B MALLUR
Professor
Mechanical Engineering Department

LABORATORY SAFETY PRECAUTIONS
1. Laboratory uniform, shoes & safety glasses are compulsory in the lab.
2. Do not touch anything with which you are not completely familiar. Carelessness may not only
break the valuable equipment in the lab but may also cause serious injury to you and others in
the lab.
3. Please follow instructions precisely as instructed by your supervisor. Do not start the
experiment unless your setup is verified & approved by your supervisor.
4. Do not leave the experiments unattended while in progress.
5. Do not crowd around the equipment’s & run inside the laboratory.
6. During experiments material may fail and disperse, please wear safety glasses and maintain a
safe distance from the experiment.
7. If any part of the equipment fails while being used, report it immediately to your supervisor.
Never try to fix the problem yourself because you could further damage the equipment and
harm yourself and others in the lab.
8. Keep the work area clear of all materials except those needed for your work and cleanup after
your work.
‘Instructions to the Candidates’
1. Students should come with thorough preparation for the experiment to be conducted.
2. Students will not be permitted to attend the laboratory unless they bring the practical record
fully completed in all respects pertaining to the experiment conducted in the previous class.
3. Experiment should be started only after the staff-in-charge has checked the experimental
setup.
4. All the calculations should be made in the observation book. Specimen calculations for one set
of readings have to be shown in the practical record.
5. Wherever graphs are to be drawn, A-4 size graphs only should be used and the same should be
firmly attached to the practical record.
6. Practical record should be neatly maintained.
7. They should obtain the signature of the staff-in-charge in the observation book after
completing each experiment.
8. Theory regarding each experiment should be written in the practical record before procedure
in your own words.

OBJECTIVES
The objectives of Foundry & Forging lab is
1. To provide an insight into different sand preparation and foundry equipment.
2. To provide an insight into different forging tools and equipment and arc welding tools and
equipment.
3. To provide training to students to enhance their practical skills in welding, forging and hand
moulding.
4. To practically demonstrate precautions to be taken during casting, hot working and welding
operations.
OUTCOMES
Course Outcomes: At the end of the course the student will be able to:
1. Demonstrate various skills in preparation of molding sand for conducting tensile, shear and
compression tests using Universal sand testing machine.
2. Demonstrate skills in determining permeability, clay content and Grain Fineness Number of base
sands.
3. Demonstrate skills in preparation of forging models involving upsetting, drawing and bending
operations.

CONTENTS
UNIT – 1
TESTING OF MOULD AND CORE SAND
Exp.No Title of the Experiment Page No
PART A PART A PART A
Testing of Molding sand and Core sand.
1
Compression strength test for moulding sand
Shear strength test for moulding sand
Tensile strength test of core sand
Permeability test
Core hardness and mould hardness test
Sieve analysis to find grain fineness number of base sand
Clay content test
Welding Practice:
Use of Arc welding tools and welding equipment
Preparation of welded joints using Arc Welding equipment
L-Joint, T-Joint, Butt joint, V-Joint, Lap joints on M.S. flats
PART B PART B PART B
Foundry Practice:
2
Foundry Practice:
Use of foundry tools and other equipment for Preparation of molding sand
mixture.
Preparation of green sand molds kept ready for pouring in the following cases:
4. Using two molding boxes (hand cut molds).
5. Using patterns (Single piece pattern and Split pattern).
6. Incorporating core in the mold.(Core boxes).
• Preparation of one casting (Aluminium or cast iron-Demonstration only)
Foundry -Introduction
Core and Core Making
Solid Pattern
Hand Cutting
Self-Cored Pattern
Stepped Cone Pulley with Core Print
Split Pattern with Two Halves
Split Pattern with Two Halves
PART C PART C PART C
Forging Operations:
03
Forging Operations: Use of forging tools and other forging equipment.
• Calculation of length of the raw material required to prepare the model
considering scale loss.
• Preparing minimum three forged models involving upsetting, drawing and
bending operations.

PART –A
Preparation of sand specimens and conduction of the following tests:
1. Compression, Shear and Tensile tests on Universal Sand Testing
Machine.
2. Permeability test
3. Sieve Analysis to find Grain Fineness Number (GFN) of Base Sand
4. Clay content determination on Base Sand.
Welding Practice:
Use of Arc welding tools and welding equipment
Preparation of welded joints using Arc Welding equipment
L-Joint, T-Joint, Butt joint, V-Joint, Lap joints on M.S. flats
PART – A

TESTING OF MOULD SAND AND CORE SAND
PROPERTIES OF MOULDING SAND
1.1. INTRODUCTION
A suitable and workable material possessing high refractoriness in nature can be used for mould making.
Thus, the mold making material can be metallic or non-metallic. For metallic category, the common
materials are cast iron, mild steel and alloy steels. In the non-metallic group molding sands, plaster of
paris, graphite, silicon carbide and ceramics are included. But, out of all, the molding sand is the most
common utilized non-metallic molding material because of its certain inherent properties namely
refractoriness, chemical and thermal stability at higher temperature, high permeability and workability
along with good strength. Moreover, it is also highly cheap and easily available. This chapter discusses
molding and core sand, the constituents, properties, testing and conditioning of molding and core sands,
procedure for making molds and cores, mold and core terminology and different methods of molding.
1.2. MOLDING SAND
The general sources of receiving molding sands are the beds of sea, rivers, lakes, granulular elements of
rocks, and deserts. The common sources of molding sands available in India are as follows:
1 Batala sand ( Punjab)
2 Ganges sand (Uttar Pradesh)
3 Oyaria sand (Bihar)
4 Damodar and Barakar sands (Bengal- Bihar Border)
5 Londha sand (Bombay)
6 Gigatamannu sand (Andhra Pradesh) and
7 Avadi and Veeriyambakam sand (Madras)
Molding sands may be of two types namely natural or synthetic. Natural molding sands contain sufficient
binder. Whereas synthetic molding sands are prepared artificially using basic sand molding constituents
(silica sand in 88-92%, binder 6-12%, water or moisture content 3-6%) and other additives in proper
proportion by weight with perfect mixing and mulling in suitable equipments.
1.3. CONSTITUENTS OF MOLDING SAND
The main constituents of molding sand involve silica sand, binder, moisture content and additives.
1.3.1 Silica sand
Silica sand in form of granular quarts is the main constituent of molding sand having enough
refractoriness which can impart strength, stability and permeability to molding and core sand. But along
with silica small amounts of iron oxide, alumina, lime stone, magnesia, soda and potash are present as
impurities. The chemical composition of silica sand gives an idea of the impurities like lime, magnesia,
alkalis etc. present. The presence of excessive amounts of iron oxide, alkali oxides and lime can lower the
fusion point to a considerable extent which is undesirable. The silica sand can be specified according to
the size (small, medium and large silica sand grain) and the shape (angular, sub-angular and rounded).
1.3.1.1 Effect of grain shape and size of silica sand
The shape and size of sand grains has a significant effect on the different properties of molding and core
sands. The shape of the sand grains in the mold or core sand determines the possibility of its application
in various types of foundry practice. The shape of foundry sand grains varies from round to angular. Some
sands consist almost entirely of grains of one shape, whereas others have a mixture of various shapes.
According to shape, foundry sands are classified as rounded, sub-angular, angular and compound. Use of
angular grains (obtained during crushing of rocks hard sand stones) is avoided as these grains have a large
surface area. Molding sands composed of angular grains will need higher amount of binder and moisture

content for the greater specific surface area of sand grain. However, a higher percentage of binder is
required to bring in the desired strength in the molding sand and core sand. For good molding purposes, a
smooth surfaced sand grains are preferred. The smooth surfaced grain has a higher sinter point, and the
smooth surface secures a mixture of greater permeability and plasticity while requiring a higher
percentage of blind material. Rounded shape silica sand grain sands are best suited for making permeable
molding sand. These grains contribute to higher bond strength in comparison to angular grain. However,
rounded silica sand grains sands have higher thermal expandability than angular silica grain sands. Silica
sand with rounded silica sand grains gives much better compactability under the same conditions than
the sands with angular silica grains. This is connected with the fact that the silica sand with rounded
grains having the greatest degree of close packing of particles while sand with angular grains the worst.
The green strength increases as the grains become more rounded. On the other hand, the grade of
compactability of silica sands with rounded sand grains is higher, and other, the contact surfaces between
the individual grains are greater on rounded grains than on angular grains. As already mentioned above,
the compactability increases with rounded grains. The permeability or porosity property of molding sand
and core sand therefore, should increase with rounded grains and decrease with angular grains. Thus the
round silica sand grain size greatly influences the properties of molding sand. The characteristics of sub-
angular sand grains lie in between the characteristics of sand grains of angular and rounded kind.
Compound grains are cemented together such that they fail to get separated when screened through a
sieve. They may consist of round, sub-angular, or angular sub-angular sand grains. Compound grains
require higher amounts of binder and moisture content also. These grains are least desirable in sand
mixtures because they have a tendency to disintegrate at high temperatures. Moreover the compound
grains are cemented together and they fail to separate when screened Grain sizes and their distribution in
molding sand influence greatly the properties of the sand. The size and shape of the silica sand grains
have a large bearing upon its strength and other general characteristics. The sand with wide range of
particle size has higher compactability than sand with narrow distribution. The broadening of the size
distribution may be done either to the fine or the coarse side of the distribution or in both directions
simultaneously, and a sand of higher density will result. Broadening to the coarse side has a greater effect
on density than broadening the distribution to the fine sand. Wide size distributions favour green
strength, while narrow grain distributions reduce it. The grain size distribution has a significant effect on
permeability. Silica sand containing finer and a wide range of particle sizes will have low permeability as
compared to those containing grains of average fineness but of the same size i.e. narrow distribution. The
compactability is expressed by the green density obtained by three ram strokes. Finer the sand, the lower
is the compactability and vice versa. This results from the fact that the specific surface increases as the
grain size decreases. As a result, the number of points of contact per unit of volume increases and this in
turn raises the resistance to compacting. The green strength has a certain tendency, admittedly not very
pronounced, towards a maximum with a grain size which corresponds approximately to the medium grain
size. As the silica sand grains become finer, the film of bentonite becomes thinner, although the
percentage of bentonite remains the same. Due to reducing the thickness of binder film, the green
strength is reduced. With very coarse grains, however, the number of grains and, therefore, the number
of points of contact per unit of volume decreases so sharply that the green strength is again reduced. The
sands with grains equal but coarser in size have greater void space and have, therefore greater
permeability than the finer silica sands. This is more pronounced if sand grains are equal in size.
1.3.2 Binder
In general, the binders can be either inorganic or organic substance. The inorganic group includes clay
sodium silicate and port land cement etc. In foundry shop, the clay acts as binder which may be Kaolonite,

Ball Clay, Fire Clay, Limonite, Fuller’s earth and Bentonite. Binders included in the organic group are
dextrin, molasses, cereal binders, linseed oil and resins like phenol formaldehyde, urea formaldehyde etc.
Organic binders are mostly used for core making. Among all the above binders, the bentonite variety of
clay is the most common. However, this clay alone can not develop bonds among sand grins without the
presence of moisture in molding sand and core sand.
1.3.3 Moisture
The amount of moisture content in the molding sand varies generally between 2 to 8 percent. This
amount is added to the mixture of clay and silica sand for developing bonds. This is the amount of water
required to fill the pores between the particles of clay without separating them. This amount of water is
held rigidly by the clay and is mainly responsible for developing the strength in the sand. The effect of clay
and water decreases permeability with increasing clay and moisture content. The green compressive
strength first increases with the increase in clay content, but after a certain value, it starts decreasing. For
increasing the molding sand characteristics some other additional materials besides basic constituents are
added which are known as additives.
1.3.4 Additives
Additives are the materials generally added to the molding and core sand mixture to develop some
special property in the sand. Some common used additives for enhancing the properties of molding and
core sands are discussed as under.
1.3.4.1 Coal dust
Coal dust is added mainly for producing a reducing atmosphere during casting. This reducing atmosphere
results in any oxygen in the poles becoming chemically bound so that it cannot oxidize the metal. It is
usually added in the molding sands for making molds for production of grey iron and malleable cast iron
castings.
1.3.4.2 Corn flour
It belongs to the starch family of carbohydrates and is used to increase the collapsibility of the molding
and core sand. It is completely volatilized by heat in the mould, thereby leaving space between the sand
grains. This allows free movement of sand grains, which finally gives rise to mould wall movement and
decreases the mold expansion and hence defects in castings. Corn sand if added to molding sand and core
sand improves significantly strength of the mold and core.
1.3.4.3 Dextrin
Dextrin belongs to starch family of carbohydrates that behaves also in a manner similar to that of the corn
flour. It increases dry strength of the molds.
1.3.4.4 Sea coal
Sea coal is the fine powdered bituminous coal which positions its place among the pores of the silica sand
grains in molding sand and core sand. When heated, it changes to coke which fills the pores and is
unaffected by water: Because to this, the sand grains become restricted and cannot move into a dense
packing pattern. Thus, sea coal reduces the mould wall movement and the permeability in mold and core
sand and hence makes the mold and core surface clean and smooth.
1.3.4.5 Pitch
It is distilled form of soft coal. It can be added from 0.02 % to 2% in mold and core sand. It enhances hot
strengths, surface finish on mold surfaces and behaves exactly in a manner similar to that of sea coal.
1.3.4.6 Wood flour
This is a fibrous material mixed with a granular material like sand; its relatively long thin fibers prevent
the sand grains from making contact with one another. It can be added from 0.05 % to 2% in mold and

core sand. It volatilizes when heated, thus allowing the sand grains room to expand. It will increase mould
wall movement and decrease expansion defects. It also increases collapsibility of both of mold and core.
1.3.4.7 Silica flour
It is called as pulverized silica and it can be easily added up to 3% which increases the hot strength and
finish on the surfaces of the molds and cores. It also reduces metal penetration in the walls of the molds
and cores.
1.4. KINDS OF MOULDING SAND
Molding sands can also be classified according to their use into number of varieties which are described
below.
1.4.1 Green sand
Green sand is also known as tempered or natural sand which is a just prepared mixture of silica sand with
18 to 30 percent clay, having moisture content from 6 to 8%. The clay and water furnish the bond for
green sand. It is fine, soft, light, and porous. Green sand is damp, when squeezed in the hand and it
retains the shape and the impression to give to it under pressure. Molds prepared by this sand are not
requiring backing and hence are known as green sand molds. This sand is easily available and it possesses
low cost. It is commonly employed for production of ferrous and non-ferrous castings.
1.4.2 Dry sand
Green sand that has been dried or baked in suitable oven after the making mold and cores, is called dry
sand. It possesses more strength, rigidity and thermal stability. It is mainly suitable for larger castings.
Mold prepared in this sand are known as dry sand molds.
1.4.3 Loam sand
Loam is mixture of sand and clay with water to a thin plastic paste. Loam sand possesses high clay as
much as 30-50% and 18% water. Patterns are not used for loam molding and shape is given to mold by
sweeps. This is particularly employed for loam molding used for large grey iron castings.
1.4.4 Facing sand
Facing sand is just prepared and forms the face of the mould. It is directly next to the surface of the
pattern and it comes into contact molten metal when the mould is poured. Initial coating around the
pattern and hence for mold surface is given by this sand. This sand is subjected severest conditions and
must possess, therefore, high strength refractoriness. It is made of silica sand and clay, without the use of
used sand. Different forms of carbon are used to prevent the metal burning into the sand. A facing sand
mixture for green sand of cast iron may consist of 25% fresh and specially prepared and 5% sea coal. They
are sometimes mixed with 6-15 times as much fine molding sand to make facings. The layer of facing sand
in a mold usually ranges from 22-28 mm. From 10 to 15% of the whole amount of molding sand is the
facing sand.
1.4.5 Backing sand
Backing sand or floor sand is used to back up the facing sand and is used to fill the whole volume of the
molding flask. Used molding sand is mainly employed for this purpose. The backing sand is sometimes
called black sand because that old, repeatedly used molding sand is black in color due to addition of coal
dust and burning on coming in contact with the molten metal.
1.4.6 System sand
In mechanized foundries where machine molding is employed. A so-called system sand is used to fill the
whole molding flask. In mechanical sand preparation and handling units, no facing sand is used. The used
sand is cleaned and re-activated by the addition of water and special additives. This is known as system
sand. Since the whole mold is made of this system sand, the properties such as strength, permeability and
refractoriness of the molding sand must be higher than those of backing sand.
1.4.7 Parting sand

Parting sand without binder and moisture is used to keep the green sand not to stick to the attern and
also to allow the sand on the parting surface the cope and drag to separate without clinging. This is clean
clay-free silica sand which serves the same purpose as parting dust.
1.4.8 Core sand
Core sand is used for making cores and it is sometimes also known as oil sand. This is highly rich silica
sand mixed with oil binders such as core oil which composed of linseed oil, resin, light mineral oil and
other bind materials. Pitch or flours and water may also be used in large cores for the sake of economy.
1.5 PROPERTIES OF MOULDING SAND
The basic properties required in molding sand and core sand are described as under.
1.5.1 Refractoriness
Refractoriness is defined as the ability of molding sand to withstand high temperatures without breaking
down or fusing thus facilitating to get sound casting. It is a highly important characteristic of molding
sands. Refractoriness can only be increased to a limited extent. Molding sand with poor refractoriness
may burn on to the casting surface and no smooth casting surface can be obtained. The degree of
refractoriness depends on the SiO2 i.e. quartz content, and the shape and grain size of the particle. The
higher the SiO2 content and the rougher the grain volumetric composition the higher is the refractoriness
of the molding sand and core sand. Refractoriness is measured by the sinter point of the sand rather than
itsmelting point.
1.5.2 Permeability
It is also termed as porosity of the molding sand in order to allow the escape of any air, gases or moisture
present or generated in the mould when the molten metal is poured into it. All these gaseous generated
during pouring and solidification process must escape otherwise the casting becomes defective.
Permeability is a function of grain size, grain shape, and moisture and clay contents in the molding sand.
The extent of ramming of the sand directly affects the permeability of the mould. Permeability of mold
can be further increased by venting using vent rods
1.5.3 Cohesiveness
It is property of molding sand by virtue which the sand grain particles interact and attract each other
within the molding sand. Thus, the binding capability of the molding sand gets enhanced to increase the
green, dry and hot strength property of molding and core sand.
1.5.4 Green strength
The green sand after water has been mixed into it, must have sufficient strength and toughness to permit
the making and handling of the mould. For this, the sand grains must be adhesive, i.e. thev must be
capable of attaching themselves to another body and. therefore, and sand grains having high
adhesiveness will cling to the sides of the molding box. Also, the sand grains must have the property
known as cohesiveness i.e. ability of the sand grains to stick to one another. By virtue of this property, the
pattern can be taken out from the mould without breaking the mould and also the erosion of mould wall
surfaces does not occur during the flow of molten metal. The green strength also depends upon the grain
shape and size, amount and type of clay and the moisture content.
1.5.5 Dry strength
As soon as the molten metal is poured into the mould, the moisture in the sand layer adjacent to the hot
metal gets evaporated and this dry sand layer must have sufficient strength to its shape in order to avoid
erosion of mould wall during the flow of molten metal. The dry strength also prevents the enlargement of
mould cavity cause by the metallostatic pressure of the liquid metal.
1.5.6 Flowability or plasticity
It is the ability of the sand to get compacted and behave like a fluid. It will flow uniformly to all portions of
pattern when rammed and distribute the ramming pressure evenly all around in all directions. Generally

sand particles resist moving around corners or projections. In general, flowability increases with decrease
in green strength, an, decrease in grain size. The flowability also varies with moisture and clay content.
1.5.7 Adhesiveness
It is property of molding sand to get stick or adhere with foreign material such sticking of molding sand
with inner wall of molding box
1.5.8 Collapsibility
After the molten metal in the mould gets solidified, the sand mould must be collapsible so that free
contraction of the metal occurs and this would naturally avoid the tearing or cracking of the contracting
metal. In absence of this property the contraction of the metal is hindered by the mold and thus results in
tears and cracks in the casting. This property is highly desired in cores
1.5.9 Miscellaneous properties
In addition to above requirements, the molding sand should not stick to the casting and should not
chemically react with the metal. Molding sand should be cheap and easily available. It should be reusable
for economic reasons. Its coefficients of expansion should be sufficiently low.
1.6 SAND TESTING
Molding sand and core sand depend upon shape, size composition and distribution of sand grains,
amount of clay, moisture and additives. The increase in demand for good surface finish and higher
accuracy in castings necessitates certainty in the quality of mold and core sands. Sand testing often allows
the use of less expensive local sands. It also ensures reliable sand mixing and enables a utilization of the
inherent properties of molding sand. Sand testing on delivery will immediately detect any variation from
the standard quality, and adjustment of the sand mixture to specific requirements so that the casting
defects can be minimized. It allows the choice of sand mixtures to give a desired surface finish. Thus sand
testing is one of the dominating factors in foundry and pays for itself by obtaining lower per unit cost and
increased production resulting from sound castings. Generally the following tests are performed to judge
the molding and casting characteristics of foundry sands:
1. Moisture content Test
2. Clay content Test
3. Chemical composition of sand
4. Grain shape and surface texture of sand.
5. Grain size distribution of sand
6. Specific surface of sand grains
7. Water absorption capacity of sand
8. Refractoriness of sand
9. Strength Test
10. Permeability Test
11. Flowability Test
12. Shatter index Test
13. Mould hardness Test.
Some of the important sand tests are discussed as under.
Moulding Material and Properties
A large variety of melding materials is used in foundries for manufacturing molds and cores. They include
moulding sand, system sand or backing sand, facing sand, parting sand, and core sand. The choice of
moulding materials is based on their processing properties. The properties that are generally required in
moulding materials are:

Flowability –
a. It is ability of molding sand to get compacted to a uniform density. Flow ability assists moulding
sand to flow and pack all around the pattern and take up the required shape.
b. The sand mould should response to different molding processes.
c. Flowability increases as the clay and water content increases.
Green Strength -
a. The molding sand that contains moisture is termed as green sand. The strength of the sand in
green or moist state is termed as green strength.
b. A mould with adequate green strength will be able to retain its shape and will not distort or
collapse.
c. The green sand particles have the ability to cling to each other to impart sufficient strength to the
mould.
Collapsibility -
a. It is property due to which the sand mould automatically gets collapsed after casting solidifies.
b. The moulding sand should also have collapsibility so that during the contraction of the casting it
does not provide any resistance, which may result in the cracks in the casting.
Dry Strength -
a. It is the strength of the moulding sand in dry conditions.
b. When the molten metal is poured in the mould, the sand around the mould cavity is quickly
converted into dry sand as the moisture in the sand evaporates due to the heat of the molten
metal.
c. At this stage the moulding sand must possess the sufficient strength to retain the exact shape of
the mould cavity and at the same time it must be able to withstand the metallostatic pressure of
the liquid material.
d. Dry sand strength is related to grain size, binder and water content.
Permeability -
a. During pouring and subsequent solidification of a casting, a large amount of gases and steam is
generated. These gases are those that have been absorbed by the metal during melting, air
absorbed from the atmosphere and the steam generated by the moulding and core sand. The
binder, additives, etc. present in the moulding sand also produce steam and other gases.
b. If these gases are not allowed to escape from the mould, they would be entrapped inside the
casting and cause casting defects.
c. To overcome this problem the moulding material must be porous or permeable to provide path
for the escape of gases. Proper venting of the mould also helps in escaping the gases that are
generated inside the mould cavity.
d. Sand with Coarse grains exhibit more permeability.
e. In absence of permeability the defects like surface blows, gas holes, etc. may be experienced.
Hot Strength -
a. It is strength of the sand above 212oF.
b. As soon as the moisture is eliminated, the sand would reach at a high temperature when the
metal in the mould is still in liquid state.
c. The strength of the sand that is required to hold the shape of the cavity is called hot strength.
d. In absence of hot strength the mould may enlarge, break, erode or get cracked.
Durability –
a. The moulding sand should possess the capacity to withstand repeated cycles of heating and
cooling during casting process
b. Moulding sand should be chemically immune to molten metals.

c. Should be reusable.
d. It should be easy to prepare and control.
Refractoriness -
a. It is the ability of the moulding material to withstand the temperature of the liquid metal to be
poured so that it does not get cracked, fused with the metal or experience any major physical
change.
b. Refractoriness is essential while casting high melting point materials.
c. The refractoriness of the silica sand is highest.
Fineness –
a. Finer sand moulds resists metal penetration and produces smooth casting surface.
b. Fineness and permeability are in conflict with each other and hence they must be balanced for
optimum results.
Bench Life –
a. It is ability of the moulding sand to retain its properties during storage.
Besides these specific properties the moulding material should be cheap, reusable, coefficient of
expansion, durability and should have
good thermal conductivity.
MOLDING SAND COMPOSITION
The main ingredients of any moulding sand are:
 Base sand,
 Binder, and
 Moisture
Base Sand
1. Silica sand is most commonly used base sand.
2. Other base sands that are also used for making mould are zircon sand, Chromite sand and olivine
sand.
3. Silica sand is cheapest among all types of base sand and it is easily available.
Binder
1. Binders are of many types such as, Clay binders, Organic binders and Inorganic binders
2. Clay binders are most commonly used binding agents mixed with the moulding sands to provide
the strength.
3. The most popular clay types are: Kaolinite or fire clay (Al2O3 2SiO2 2H2O) and Bentonite (Al2O3
4SiO2 nH2O)
4. Bentonite can absorb more water than fire clay which increases its bonding power.
Water (Moisture)
1. Clay acquires its bonding action only in the presence of the required amount of moisture.
2. When water is added to clay, it penetrates the mixture and forms a microfilm, which coats the
surface of each flake of the clay.
3. The amount of water used should be properly controlled.
4. This is because a part of the water, which coats the surface of the clay flakes, helps in bonding,
while the remainder helps in improving the plasticity.
Table 4 : A Typical Composition of Molding Sand

Molding Sand Constituent Weight Percent
Silica sand 92
Clay (Sodium Bentonite) 8
Water 4
SAND TESTING EXPERIMENTS
Periodic test are necessary to determine the essential qualities of foundry sand.
The most important tests to be conducted for any foundry sand are as follows.
1. Compression, shear and tensile strength test on universal sand testing machine.
Purpose:
i) Moulding sand must have good strength otherwise it may lead to collapse of mould.
ii) It must be retained when the molten metal enters the mould (bond strength)
iii) To retain its shape when the patter is removed and movement of the mould.
2. Permeability test.
It is the property of moulding sand which allows gases to pass through easily in the mould.
3. Core and mould hardness test.
The hardness test is useful to find out the moulds surface uniformly.
4. Sieve analysis to find the grain fineness number of base sand.
To find the average grain fineness number for the selection of fine, medium, and course sand.
5. Clay content determination in base sand.
It is to find the % of the clay content in the base sand.

ExperimentNo.1 Date:
COMPRESSION STRENGTH TEST FOR MOULDING SAND
AIM: To find the green compression strength of the given specimen at different percentage of clay and
moisture
Materials used: Base sand, clay, water,
Apparatus used: Sand Ramming machine (Rammer) with specimen tube with base, stripper, universal
sand testing machine with Compression shackles, weighing pan, measuring jar, steel scale, Electronic
weighing scale.
Theory:
1. Periodic tests are necessary to check the quality of foundry sand and compression strength test is one
among them.
2. The constituents of moulding sand are silica sand, clay, water and other special additives.
3. Clay imparts the necessary bonding strength to the moulding sand when it is mixed with water etc.
bentonite.
4. Compression test determines the bonding or adhesiveness power of various bonding materials in
greensand.
5. The green compressive strength of foundry sand is the maximum compression strength a mixture is
capable of developing when it is in most condition.
Procedure:
1. Conduct the experiment in two parts:
a) Vary the clay content keeping the water content constant
b) Vary the water content keeping the clay content constant
2. Take weighed proportions of sand and clay and dry mix them together in a Muller for 3 minutes.
3. Adjust the weight (168gms) of the sand to get standard specimen.
4. Transfer the sand mixture into the specimen tube and ram it with the help of a sand rammer
thrice.
5. Remove the standard specimen by the stripper and place it between shackles which are fixed in
the sand testing machine.
6. Preliminary adjustments are made before applying the hydraulic pressure of the testing machine
7. Rotate the handle of the testing machine to actuate the ram. Thus hydraulic pressure is applied
continuously till the specimen raptures.
8. Read the compression strength from the gauge and record the same.
9. Conduct the experiment for the above said two cases and tabulate the result.
Result and discussion
Plot the graphs with compression strength on y-axis & percentage clay on x-axis and the other with
compression strength on y-axis v/s percentage water on x-axis.
Discuss the result with respect to the variation of percentage of clay on compression strength and
percentage of water on compression strength.

TABULAR COLUMN
D=50mm
Weight of sand=150 gms
1. VARYING THE % OF CLAY
SL.
NO
Weight
of sand
Percentage
of clay
Percentage
of water
compression
strength gm/cm2
1 150gms 4%(8gms)
2 150gms 5%(10gms)
3 150gms 6%(12gms)
4 150gms 7%(14gms)
2. VARYING THE % OF WATER
SL.
NO
Percentage
of sand
Percentage
of clay
Percentage
of water
compression
strength gm/cm2
1 150gms 4%(8gms)
2 150gms 5%(10gms)
3 150gms 6%(12gms)
4 150gms 7%(14gms)
Percentage of water= 150x4/ 100 =6.0

Fig 1.1 Universal Strength Machine
Fig 1.2 Sand Rammer
Date……………. Signature of the Faculty

Experiment No. 2 Date: __ /__ / _____
SHEAR STRENGTH TEST FOR MOULDING SAND
AIM: To determine the green shear strength of the given specimen for different percentages of clay and
moisture.
Materials used: Base sand, clay, water.
Apparatus used: Sand ramming machine (rammer), universal sand testing machine with attachments,
weighing pan.
Theory:
1. Shear strength is the ability of sand particles to resist the shear stress and to stick together.
2. Insufficient Shear strength may lead to the collapsing of sand in the mould or it’s partial
destruction during handling. The mould and core may also be damaged during flow of molten
metal in the mould cavity.
3. The moulding sand must possess sufficient strength to permit the mould to be formed to the
desired shape and to retain the shape even after the hot metal is poured into the mould cavity.
4. In shearing, the rupture occurs parallel to the axis of the specimen.
Procedure:
1. Conduct the experiment in two parts:
a) Vary the clay content keeping the water content constant
b) Vary the water content keeping the clay content constant
2. Take weighed amount of foundry sand (mixture of sand, clay & water as specified).
3. Transfer the sand mixture into the tube and ram it with the help of a sand rammer thrice.
4. Fix the shackles to the universal
sand testing machine.
5. Remove the specimen from the
tube with the help of a stripper
and load it into the universal
sand testing machine.
6. Preliminary adjustments are
made before applying the
hydraulic pressure of the
testing machine
7. Apply the hydraulic pressure by rotating the handle of the universal sand testing machine
continuously until the specimen ruptures.
8. Read the shear strength directly from the scale and tabulate the readings.

TABULAR COLUMN
1. VARYING THE % OF CLAY
SL.
NO
Weight
of sand
Percentage
of clay
Percentage
of water
compression
strength gm/cm2
1 150gms) 4%(8gms) 5%(10gms)
2 150gms) 5%(10gms) 5%(10gms)
3 150gms) 6%(12gms) 5%(10gms)
150gms) 7%(12gms)
2. VARYING THE % OF WATER
SL.
NO
Percentage
of sand
Percentage
of clay
Percentage
of water
compression
strength gm/cm2
1 90%(180gms) 6%(12gms) 4%(08gms)
2 89%(178gms) 6%(12gms) 5%(10gms)
3 88%(176gms) 6%(12gms) 6%(12gms)
Graphs:
a) Shear strength (Y-axis) V/s Percentage
of clay (X-axis).
b) Shear strength (Y-axis) V/s Percentage
of water (X-axis).
Results and Discussions:
The Graphs above reveal:
a) With the increase in the percentage of water the shear strength of the specimen …………………………….
b) With the increase in the percentage of clay the shear strength of the specimen …………………………….

TENSILE STRENGTH TEST OF CORE SAND
AIM: To determine the tensile strength of sand using two types of binders Viz. core oil binder and sodium
silicate binder.
Materials used: Base sand, core oil, sodium silicate.
Apparatus used: universal sand testing machine, Split core box, Sand rammer, oven, tension shackles.
Theory:
1. A core is compacted sand mass of a known shape.
2. When a hollow casting (to have a hole – through or bind) is required, a core is used in the mould
or when a complex contour is required a mould is created out of cores. This core has to be
properly seated in the mould on formed impressions in the sand. To form these impressions
extra projections called core points are added on the pattern surface at proper places.
3. Core boxes are used for making cores. They are either made single or in two parts. Their
classification is generally according to the shape of the core or the method of making the core.
4. Split core box is very widely used and is made in two parts, which can be joined together by
means of dowels to form the complete cavity for making the core.
5. The purpose of adding binder to the moulding sand is to impart strength and cohesiveness to the
sand to enable it to retain its shape after the core has been rammed.
6. binders used can be
a) organic: ex. Dextrin, core oil
b) Inorganic: ex. Sodium silicate, Bentonite
7. Classification of binders:
a. Baking type: Binding action is realized in the sand after baking the sand mixture in an oven.
b. Gassing type: Binding action is obtained in the sand after passing a known gas through the
sand mixture.
3. Ex. Co2 gas passed through a mixture of sand and sodium silicate.
8. Core oil is used as binder that hardens with the addition of heat. The sand and binder is mixed
and backed at a temperature of 250O – 300O C and binding action takes place within few hours.
9. Sodium silicate is a self-setting binder and no external heat is required for the binding action
which takes place at room temperature when Co2 gas is passed.
10. During casting the core is placed inside the mould and the molten metal is poured in to the
cavity. As the molten metal begins to cool, it begins to contract on the inner radius as well as the
outer radius. Due to the contraction of the inner radius the core sand will be pulled outwards
causing a tensile load around the core. Hence knowledge of tensile strength of core sand is
important.
Procedure:
1. Conduct the experiment as mention below
2. Take proper proportions of base sand and binder then mix them together thoroughly.

3. Assembly the core box and fill the mixture into it.
4. Place the core box under sand rammer and ram the sand thrice.
5. Using a wooden piece tap the core box gently from sides. Remove the core box leaving the
rammed core on a flat metal plate
6. Bake the specimen (which is on a plate) for about 30 minutes at a temperature of 150O – 200O C
in an oven. (When the binder is core oil)
7. If the binder is sodium silicate, pass Co2 gas for 5 secs. The core hardens instantly and the core
can be directly used.
8. Fix the tension shackles on to the sand testing machine, and place the hardened specimen in the
shackles.
9. Apply the load gradually by turning the hand wheel of the testing machine. Note down the
readings when the specimen breaks.
10. Repeat the procedure for the different percentage of binder and tabulate the readings.
TABULAR COLUMN
SL.NO Weight
of sand
Percentage of moisture Tensile strength N/m2
150gms
Result and discussion:
Plot the graph of tensile strength on y-axis and binder on x-axis. Discuss the effect of variation of binder
content on tensile strength.
Figures to be drawn:
1) Split core box for tensile specimen(Fig. 3.1)
2) Tensile stress on core(Fig. 3.2 a and Fig.3.2 b)
3) Dimensions of standard tensile specimen(Fig.3.3)
4) Tensile test shackles(Fig. 3.4)

Fig. 3.1 Split core box (Tension) Fig. 3.3 Dimensions of standard tensile
Fig. 3.4 Tensile test shackles

Fig. 3.2 a: Tensile Core Box
Fig. 3.2 b: Tensile strength attachment

PERMEABILITY TEST
AIM: To find the effect of water content, clay content on green permeability of foundry sand.
Materials used: Base sand, clay and water.
Apparatus used: Sand rammer, Permeability meter, Electronic weighing scale, stripper, stop watch,
measuring jar, specimen tube, specimen tube cup.
Theory:
1. Molten metals always contain certain amount of dissolved gases, which are evolved when the
metal starts freezing.
2. When molten meal comes in contact with moist sand, generates steam or water vapour.
3. Gases and water vapour are released in the mould cavity by the molten metal and sand. If they
do not find opportunity to escape completely through the mould, they will get entrapped and
form gas holes or pores in the casting. The sand must therefore be sufficiently porous to allow
the gases and water vapour to escape out. This property of sand is referred to as permeability.
4. Permeability is one of the most important properties affecting the characteristic of moulds
which depends upon the grain size, grain shape, grain distribution, binder content, moisture
level and degree of compactness.
5. Permeability is a physical property of the physical sand mixture, which allows gases to pass
through it easily.
6. The AFS (American Foundry Men Society) definition of permeability is “the number obtained by
passing 2000cc of air through a standard specimen under a pressure of 10 gm/cm2 for a given
time in minutes”.
7. The permeability number PN can be found out by the equation
Where
V = Volume of air passing through the specimen, 2000cc
H = Height of the specimen = 50.8 mm (standard value)
P = Pressure as read from the manometer in gm/cm2
A = Area of t
Where d = 50.8 mm (standard value)
T= time in minutes for 2000 cc of air passed through the sand specimen.

Experimental setup details:
Permeability meter has a cylindrical water tank in which an air tank is floating. By properly opening the
valve, air from the air tank can be made to flow through the sand specimen and a back pressure is setup.
The pressure of this air is obtained with the water manometer. The meter also contains the chart, which
directly gives the PN depending on pressure.
Procedure:
1. Conduct the experiment in two parts. In the first case vary water percent keeping clay percent
constant. In the second case vary clay percent and keep water percent constant.
2. Take weighed proportions of sand dry mix them together for 3 minutes. Then add required
proportions of water and wet mix for another 2 minutes, to get a homogeneous and mixture.
Take the total weight of the mixture between 150-200 grams. The correct weight has to be
determined by trail and error method.
3. Fill the sand mixture into the specimen tube and ram thrice using sand rammer. Use the
tolerance limit provided at the top end of the rammer for checking the specimen size. If the top
end of the rammer is within the tolerance limit, the correct specimen is obtained. If it lies below
the limit, increase the weight of sand mixture and prepare a new specimen. The specimen
conforming to within limits represent the standard specimen required.
4. Now the prepared standard specimen is having a dia.50.8mm and height 50.8mm.
5. Place the standard specimen along with the tube in the inverted position on the rubber seal or
on the mercury cup (specimen in the top position in the manometer reading).
6. Operate the valve and start the stop watch simultaneously. When the zero mark on the inverted
jar just touches the top of water tank, note down the manometer reading.
7. Note down the time required to pass 2000cc of air through the specimen. Calculate the
permeability number by using the formula given.
Direct scale reading:
The permeability can also be determined by making use of the graduated marker provided near the
manometer.
Procedure to be followed:
 Coincide the graduations on the transparent scale with the meniscus of the manometer liquid.
 Note the reading of the scale.
 This reading represents the permeability number of the sand.

Draw graph:
 Permeability number v/s % Clay
 Permeability number v/s % water
 Discuss the effect of water and clay on Permeability

Fig. 4.1 Permeability Meter

CORE HARDNESS AND MOULD HARDNESS TEST
Mould and core hardness can be found out by the hardness –
tester which is base on the same principle as Brinell hardness
tester. A steel ball of 50 mm diameter weighing 237 gm is
pressed on the mould surface. The depth of penetration of
steel ball will give the hardness of mould surface on the direct
reading dial. This hardness test is useful in finding out the
mould uniformity
The following are the moulding hardness numbers for
 Moulding sand (1 number = 1/100 mm)
 Soft rammed moulds = 100 Medium
 rammed moulds = 125
 Hard rammed mould = 175
Fig. 5.1 Mould Hardness Tester

SIEVE ANALYSIS TO FIND GRAIN FINENESS NUMBER OF BASE SAND
AIM: To find the distribution of sand grains using a set of sieves and to find the average grain fineness
number.
Materials used: Base sand- Silica sand.
Apparatus used: Electronic weighing scale, stop watch, sieve shaker.
Theory:
1. The base sand is a mixture of grains having a variety of shapes such as
a) Round b) sub-angular c) angular d) compounded grains.
b. Base sand is relatively free from any binder or additives.
2. Depending on the average size of the grains, the sand can be grouped into:
a) Fine b) Medium and c) Coarse grains.
3. The shape and size of grains has a large influence on the permeability of sand mix as well as on the
bonding action.
4. The shape and size of grains determine the possibility of its application in various types of foundry
practice.
Ex: Fine grain sand results in good surface, on the casting but gases cannot escape out of the mould
made from it. Coarse grain sand allows gases to escape out easily but the casting surface will be very
rough. Hence grain size should select appropriately.
5. The given size of sand grains is designated by a number called grain fineness number that indicates
the average size of grains in the mixture.
6. The size is determined by passing the sand through sieves having specified apparatus which are
measured in microns.
7. The sieve number designates the pore size through which the sand grains, may pass through it or
retained in it.
8. Average grains fineness number can be found out by the equation
GFN = Q/P
Where
Q = sum of product of percentage sand retained in sieves and Corresponding multiplier.
P = sum of percentage of sand retained in sieves.

Procedure:
1. Take 50 gm or100 gm of dry sand and place in the top sieve of a series and close the lid.
2. Place the whole assembly of sieves on the vibratory sieve shaker and clamp it.
3. Switch on the motor and allow the sieve assembly to vibrate for 5 minutes. Then switch off the
motor.
4. Collect the sand particles retained in each of the sieve separately and weigh in Electronic
weighing scale and enter into the tabular column. Calculate the percentage weight retained by
each of the sieves. Multiply this value with the multiplier for each sieve.
(Calculate the average GFN using the formula as shown below.)
Tabular Column:

% Retained C = Weight of sand in each sieve x 100
Total weight of sand
Calculation: AFS grain number = Q (sum) / P (total)
Results; The average grain fineness number is =
Graph: Percentage of sand retained v/s sieve number
Fig. 6.1 Sieve Shaker

CLAY CONTENT TEST
AIM: To determine the percentage of clay present in base sand.
Materials used: Base sand, 5 % NaoH solution and water.
Apparatus used: Wash bottle, measuring jar, mechanical stirrer and siphon tube.
Theory:
1. Clay can be those particles having less than 20 microns size. Moulding sand contains 2 to 50
percent of clay. When mixed with water it imparts, binding strength and plasticity.
2. Clay consists of two ingredients a) Fine silt and b) True clay. Fine silt as no binding power where as
true clay imparts the necessary boundary strength to the moulding sand; thereby the mould does
not loose its shape after ramming.
3. Clay also can define as those particles which when mixed with water, agitated and then made to
settled, fails to settle down at the rate of 1”/mm.
4. The particles of clay are plate like from and have a very large surface area compared to its
thickness and therefore have a very high affinity to absorb moisture.
5. Clay is the main constituent in a moulding sand and mixture other than sand grains. Clay imparts
binding action to the sand and hence the strength.
6. Clay is of mineral origin available in plenty on earth. It is made of alumina silicate. The types of clay
are a) montmorillonite b) Kaolinite and c) illite the first type is generally referred to as
Bentonite.
Clay is the main constituent in a moulding sand mixture other than sand grain. Clay help impart binding
action to the sand and hence strength to the sand.
Procedure:
1. Take 100g of base sand in a wash bottle and add 475ml of distilled water and 25ml of NaOH
solution to it.
2. using the mechanical stirrer, stir the mixture for about 5 minutes add distilled water to make up
the level to 6"height. Stir the mixture again for 2 minutes. Now allow the content of the bottle to
settle down.
3. Siphon out 5” level of unclean water using a standard siphon.
4. Add distilled water again up to 6" height and stir the content again. Allow the mixture to settle
down for 5minutes.
5. Siphon out 5” level of water from the bottom of the bottle Repeat the above procedure for 3-
4times till the water becomes clear in the wash bottle.
6. Transfer the wet sand from the bottle in to a tray and dry in it in an oven at 110 o C to remove
moisture. Note down the dry sand weight accurately. Using the calculations find percentage of
clay.

Calculations
Weight of sand W1= 100 gms
Weight of dried sand W2 = ----------- gms
% of clay= ( W1- W2) X 100
100
Results and discussion:
The percentage of clay is =___________%
Discuss whether the % of Water is present is high or low and whether this % is enough to act as binder in
the sand.
Fig 7.1 Clay Washer

WELDING PROCESS
2.1. INTRODUCTIONS:
Welding is a process for joining two similar or dissimilar metals by fusion. It joins different metals/alloys,
with or without the application of pressure and with or without the use of filler metal. The fusion of metal
takes place by means of heat. The heat may be generated either from combustion of gases, electric arc,
electric resistance or by chemical reaction. During some type of welding processes, pressure may also be
employed, but this is not an essential requirement for all welding processes. Welding provides a
permanent joint but it normally affects the metallurgy of the components. It is therefore usually
accompanied by post weld heat treatment for most of the critical components. The welding is widely used
as a fabrication and repairing process in industries. Some of the typical applications of welding include the
fabrication of ships, pressure vessels, automobile bodies, off-shore platform, bridges, welded pipes,
sealing of nuclear fuel and explosives, etc.
Most of the metals and alloys can be welded by one type of welding process or the other. However, some
are easier to weld than others. To compare this ease in welding term ‘weldability’ is often used. The
weldability may be defined as property of a metal which indicates the ease with which it can be welded
with other similar or dissimilar metals. Weldability of a material depends upon various factors like the
metallurgical changes that occur due to welding, changes in hardness in and around the weld, gas
evolution and absorption, extent of oxidation, and the effect on cracking tendency of the joint. Plain low
carbon steel (C-0.12%) has the best weldability amongst metals. Generally it is seen that the materials
with high castability usually have low weldability.
Welding is a materials joining process which produces coalescence of materials by heating them to
suitable temperatures with or without the application of pressure or by the application of pressure alone,
and with or without the use of filler material.
Welding is used for making permanent joints. It is used in the manufacture of automobile bodies, aircraft
frames, railway wagons, machine frames, structural works, tanks, furniture, boilers, general repair work
and ship building.
Welding which is the process of joining two metallic components for the desired purpose, can be defined
as the process of joining two similar or dissimilar metallic components with the application of heat, with
or without the application of pressure and with or without the use of filler metal. Heat may be obtained
by chemical reaction, electric arc, electrical resistance, frictional heat, sound and light energy. If no filter
metal is used during welding then it is termed as ‘Autogenous Welding Process'.
During ‘Bronze Age' parts were joined by forge welding to produce tools, weapons and ornaments etc,
however, present day welding processes have been developed within a period of about a century.
First application of welding with carbon electrode was developed in 1885 while metal arc welding with
bare electrode was patented in 1890. However, these developments were more of experimental value
and applicable only for repair welding but proved to be the important base for present day manual metal
arc (MMAW) welding and other arc welding processes.

In the mean time resistance butt welding was invented in USA in the year 1886. Other resistance welding
processes such as spot and flash welding with manual application of load were developed around 1905.
With the production of cheap oxygen in 1902, oxy – acetylene welding became feasible in Europe in 1903.
When the coated electrodes were developed in 1907, the manual metal arc welding process becomes
viable for production/fabrication of components and assemblies in the industries on large scale. All
welded ‘Liberty ' ships failure in 1942, gave a big jolt to application of welding. However, it had drawn
attention to fracture problem in welded structures.
Subsequently other developments are as follows:
• Thermit Welding (1903) • Constricted Arc (Plasma) for Cutting (1955)
• Cellulosic Electrodes (1918) • Friction Welding (1956)
• Arc Stud Welding (1918) • Plasma Arc Welding (1957)
• Seam Welding of Tubes (1922) • Electro Gas Welding (1957)
• Mechanical Flash Welder for Joining Rails (1924) • Short Circuit Transfer for Low Current, Low Voltage
Welding with CO 2 Shielding (1957)
• Extruded Coating for MMAW Electrodes (1926) • Vacuum Diffusion Welding (1959)
• Submerged Arc Welding (1935) • Explosive Welding (1960)
• Air Arc Gouging (1939) • Laser Beam Welding (1961)
• Inert Gas Tungsten Arc (TIG) Welding (1941) • High Power CO 2 Laser Beam Welding (1964)
• Iron Powder Electrodes with High Recovery (1944) • Constricted Arc (Plasma) for Cutting (1955)
• Inert Gas Metal Arc (MIG) Welding (1948) • Friction Welding (1956)
• Electro Slag Welding (1951) • Plasma Arc Welding (1957)
• Flux Cored Wire with CO 2 Shielding (1954) • Electro Gas Welding (1957)
• Electron Beam Welding (1954) • Short Circuit Transfer for Low Current, Low Voltage
Welding with CO 2 Shielding (1957)
• Thermit Welding (1903) • Vacuum Diffusion Welding (1959)
• Cellulosic Electrodes (1918)
2.1.1. APPLICATIONS:
Although most of the welding processes at the time of their developments could not get their place in the
production except for repair welding, however, at the later stage these found proper place in
manufacturing/production. Presently welding is widely being used in fabrication of pressure vessels,
bridges, building structures, aircraft and space crafts, railway coaches and general applications. It is also
being used in shipbuilding, automobile, electrical, electronic and defense industries, laying of pipe lines
and railway tracks and nuclear installations etc.
Welding is vastly being used for construction of transport tankers for transporting oil, water, milk and
fabrication of welded tubes and pipes, chains, LPG cylinders and other items. Steel furniture, gates, doors
and door frames, body and other parts of white goods items such as refrigerators, washing machines,
microwave ovens and many other items of general applications are fabricated by welding.
Pressure Vessels Aircraft and Spacecraft Electronic Industry
Bridges Railways Nuclear Installations
Ship Building Automobiles Defence Industry
Building Structures Electrical Industry Micro-Joining

2.2. TERMINOLOGICAL ELEMENTS OF WELDING PROCESS
The terminological elements of welding process used with common welding joints such as base metal,
fusion zone, weld face, root face, root opening toe and root are depicted in Fig.2.1
Fig. 2.1 Terminological elements of welding process
2.2.1 Edge preparations
For welding the edges of joining surfaces of metals are prepared first. Different edge preparations may be
used for welding butt joints, which are given in Fig 2.2.
Fig. 2.2 Butt welding joints edge preparations
2.2.2 Welding joints
Some common welding joints are shown in Fig. 2.3. Welding joints are of generally of two major kinds
namely lap joint and butt joint. The main types are described as under.
2.2.2.1 Lap weld joint
Single-Lap Joint
This joint, made by overlapping the edges of the plate, is not recommended for most work. The single lap
has very little resistance to bending. It can be used satisfactorily for joining two cylinders that fit inside
one another.
Double-Lap Joint
This is stronger than the single-lap joint but has the disadvantage that it requires twice as much welding.
Tee Fillet Weld
This type of joint, although widely used, should not be employed if an alternative design is possible.

Fig. 2.3 Types of welding joints
2.2.2.2 Butt weld joint
Single-Vee Butt Weld
It is used for plates up to 15.8 mm thick. The angle of the vee depends upon the technique being used,
the plates being spaced approximately 3.2 mm.
Double-Vee Butt Weld
It is used for plates over 13 mm thick when the welding can be performed on both sides of the plate. The
top vee angle is either 60° or 80°, while the bottom angle is 80°, depending on the technique being used.

2.2.3 Welding Positions
As shown in Fig. 17.4, there are four types of welding positions, which are given as:
1. Flat or down hand position
2. Horizontal position
3. Vertical position
4. Overhead position
Fig. 2.4 Kinds of welding positions
2.2.3.1 Flat or Downhand Welding Position
The flat position or down hand position is one in which the welding is performed from the upper side of
the joint and the face of the weld is approximately horizontal. This is the simplest and the most
convenient position for welding. Using this technique, excellent welded joints at a fast speed with
minimum risk of fatigue to the welders can be obtained.
2.2.3.2 Horizontal Welding Position
In horizontal position, the plane of the workpiece is vertical and the deposited weld head is horizontal.
The metal deposition rate in horizontal welding is next to that achieved in flat or downhand welding
position. This position of welding is most commonly used in welding vessels and reservoirs.
17.2.3.3 Veritical Welding Position
In vertical position, the plane of the workpiece is vertical and the weld is deposited upon a vertical
surface. It is difficult to produce satisfactory welds in this position due to the effect of the force of gravity
on the molten metal. The welder must constantly control the metal so that it does not run or drop from
the weld. Vertical welding may be of two types viz., vertical-up and vertical-down. Vertical-up welding is
preferred when strength is the major consideration. The vertical-down welding is used for a sealing
operation and for welding sheet
metal.
17.2.3.4 Overhead Welding Position
The overhead position is probably even more difficult to weld than the vertical position. Here the pull of
gravity against the molten metal is much greater. The force of the flame against the weld serves to
counteract the pull of gravity. In overhead position, the plane of the workpiece is horizontal. But the
welding is carried out from the underside. The electrode is held with its welding end upward. It is a good
practice to use very short arc and basic coated electrodes for overhead welding.

3. CLASSIFICATION OF WELDING AND ALLIED PROCESSES
There are different welding, brazing and soldering methods are being used in industries today. There are
various ways of classifying the welding and allied processes. For example, they may be classified on the
basis of source of heat, i.e., blacksmith fire, flame, arc, etc. and the type of interaction i.e., liquid / liquid
(fusion welding) or solid/solid (solid state welding). Welding processes may also be classified in two
categories namely plastic (forge) and fusion. However, the general classification of welding and allied
processes is given as under
Pressure Welding
The piece of metal to be joined are heated to a plastic state and forced together by external pressure
(Ex) Resistance welding
Fusion Welding or Non-Pressure Welding
The material at the joint is heated to a molten state and allowed to solidify
(Ex) Gas welding, Arc welding.
(A) Welding Processes
1. Oxy-Fuel Gas Welding Processes
1 Air-acetylene welding
2 Oxy-acetylene welding
3 Oxy-hydrogen welding
4 Pressure gas welding
2. Arc Welding Processes
1. Carbon Arc Welding
2. Shielded Metal Arc Welding
3. Submerged Arc Welding
4. Gas Tungsten Arc Welding
5. Gas Metal Arc Welding
6. Plasma Arc Welding
7. Atomic Hydrogen Welding
8. Electro-slag Welding
9. Stud Arc Welding
10. Electro-gas Welding
3. Resistance Welding
1. Spot Welding
2. Seam Welding
3. Projection Welding
4. Resistance Butt Welding
5. Flash Butt Welding
6. Percussion Welding
7. High Frequency Resistance Welding
8. High Frequency Induction Welding
4. Solid-State Welding Processes
1. Forge Welding
2. Cold Pressure Welding
3. Friction Welding
4. Explosive Welding
5. Diffusion Welding

6. Cold Pressure Welding
7. Thermo-compression Welding
5. Thermit Welding Processes
1. Thermit Welding
2. Pressure Thermit Welding
6. Radiant Energy Welding Processes
1. Laser Welding
2. Electron Beam Welding
(B) Allied Processes
1. Metal Joining or Metal Depositing Processes
1. Soldering
2. Brazing
3. Braze Welding
4. Adhesive Bonding
5. Metal Spraying
6. Surfacing
2. Thermal Cuting Processes
1. Gas Cutting. 2. Arc Cutting
Welding processes can be classified based on following criteria;
1. Welding with or without filler material.
2. Source of energy of welding.
3. Arc and Non-arc welding.
4. Fusion and Pressure welding.
1. Welding can be carried out with or without the application of filler material. Earlier only gas welding
was the fusion process in which joining could be achieved with or without filler material. When
welding was done without filler material it was called ‘autogenous welding'. However, with the
development of TIG, electron beam and other welding processes such classification created confusion
as many processes shall be falling in both the categories.
2. Various sources of energies are used such as chemical, electrical, light, sound, mechanical energies,
but except for chemical energy all other forms of energies are generated from electrical energy for
welding. So this criterion does not justify proper classification.
3. Arc and Non-arc welding processes classification embraces all the arc welding processes in one class
and all other processes in other class. In such classification it is difficult to assign either of the class to
processes such as electroslag welding and flash butt welding, as in electroslag welding the process
starts with arcing and with the melting of sufficient flux the arc extinguishes while in flash butt
welding tiny arcs i.e. sparks are established during the process and then components are pressed
against each other. Therefore, such classification is also not perfect.

4. Fusion welding and pressure welding is most widely used classification as it covers all processes in
both the categories irrespective of heat source and welding with or without filler material. In
fusion welding all those processes are included where molten metal solidifies freely while in
pressure welding molten metal if any is retained in confined space under pressure (as may be in
case of resistance spot welding or arc stud welding) solidifies under pressure or semisolid metal
cools under pressure. This type of classification poses no problems so it is considered as the best
criterion. Processes falling under the categories of fusion and pressure welding are shown in
Figures 6.1 and6.2.
Figure 6.1: Classification of Fusion Welding Processes
Figure 6.2: Classification of Pressure Welding Processes

ADVANTAGES AND DISADVANTAGES OF WELDING:
Advantages:
1. Welding is more economical and is much faster process as compared to other processes (riveting,
bolting, casting etc.)
2. Welding, if properly controlled results permanent joints having strength equal or sometimes more than
base metal.
3. Large number of metals and alloys both similar and dissimilar can be joined by welding.
4. General welding equipment is not very costly.
5. Portable welding equipments can be easily made available.
6. Welding permits considerable freedom in design.
7. Welding can join welding jobs through spots, as continuous pressure tight seams, end-to-end and in a
number of other configurations.
8. Welding can also be mechanized.
Disadvantages:
1. It results in residual stresses and distortion of the work pieces.
2. Welded joint needs stress relieving and heat treatment.
3. Welding gives out harmful radiations (light), fumes and spatter.
4. Jigs, and fixtures may also be needed to hold and position the parts to be welded
5. Edges preparation of the welding jobs is required before welding
6. Skilled welder is required for production of good welding
7. Heat during welding produces metallurgical changes as the structure of the welded joint is not same
as that of the parent metal.
ARC WELDING PROCESSES
The process, in which an electric arc between an electrode and a workpiece or between two electrodes is
utilized to weld base metals, is called an arc welding process. The basic principle of arc welding is shown
in Fig 17.9(a). However the basic elements involved in arc welding process are shown in Fig. 17.9(b). Most
of these processes use some shielding gas while others employ coatings or fluxes to prevent the weld
pool from the surrounding atmosphere. The various arc welding processes are:
1. Carbon Arc Welding
2. Shielded Metal Arc Welding
3. Flux Cored Arc Welding
4. Gas Tungsten Arc Welding
5. Gas Metal Arc Welding
6. Plasma Arc Welding
7. Atomic Hydrogen Welding
8. Electroslag Welding
9. Submerged Arc Welding
10. Electrogas Welding
ARC WELDING EQUIPMENT
Arc welding equipment, setup and
related tools and accessories are shown in Fig. 6.3. Few of the important components of arc welding
setup are described as under .

Fig. 6.3 Principle of arc welding and Arc welding process setup
1. Arc welding power source
Both direct current (DC) and alternating current (AC) are used for electric arc welding, each having its
particular applications. DC welding supply is usually obtained from generators driven by electric motor or
if no electricity is available by internal combustion engines. For AC welding supply, transformers are
predominantly used for almost all arcs welding where mains electricity supply is available. They have to
step down the usual supply voltage (200-400 volts) to the normal open circuit welding voltage (50-90
volts). The following factors influence the selection of a power source:
1. Type of electrodes to be used and metals to be welded
2. Available power source (AC or DC)
3. Required output
4. Duty cycle
5. Efficiency
6. Initial costs and running costs
7. Available floor space
8. Versatility of equipment
Fig. 6.5 Earth clamp

Fig. 6.4 Electrode holder
Fig. 6.6 Wire brush Fig. 6.7 Chipping and hammer
2. Welding cables
Welding cables are required for conduction of current from the power source through the electrode
holder, the arc, the workpiece and back to the welding power source. These are insulated copper or
aluminium cables.
3. Electrode holder
Electrode holder is used for holding the electrode mannually and conducting current to it. These are
usually matched to the size of the lead, which in turn matched to the amperage output of the arc welder.
Electrode holders are available in sizes that range from 150 to 500 Amps.
4. Welding Electrodes
An electrode is a piece of wire or a rod of a metal or alloy , with or without coatings. An arc is set up
between electrode and workpiece. Welding electrodes are classified into following types-
(1) Consumable Electrodes
(a) Bare Electrodes
(b) Coated Electrodes
(2) Non-consumable Electrodes
(a) Carbon or Graphite Electrodes
(b) Tungsten Electrodes
Consumable electrode is made of different metals and their alloys. The end of this electrode starts
melting when arc is struck between the electrode and workpiece. Thus consumable electrode itself acts
as a filler metal. Bare electrodes consist of a metal or alloy wire without any flux coating on them. Coated
electrodes have flux coating which starts melting as soon as an electric arc is struck. This coating on
melting performs many functions like prevention of
joint from atmospheric contamination, arc stabilizers
etc.
Non-consumable electrodes are made up of high
melting point materials like carbon, pure tungsten or
alloy tungsten etc. These electrodes do not melt
away during welding. But practically , the electrode
length goes on decreasing with the passage of time,
because of oxidation and vaporization of the
electrode material during welding. The materials of
non- consumable electrodes are usually copper
coated carbon or graphite, pure tungsten, thoriated
or zirconiated tungsten.
5. Hand Screen

Hand screen used for protection of eyes and supervision of weld bead.
6. Chipping hammer
Chipping Hammer is used to remove the slag by striking.
7. Wire brush
Wire brush is used to clean the surface to be weld.
8. Protective clothing
Operator wears the protective clothing such as apron to keep away the exposure of direct heat to the
body.
Fig. 6.8 Principle of arc welding
CARBON ARC WELDING
In this process, a pure graphite or baked carbon rod is used as a non-consumable electrode to create an
electric arc between it and the workpiece. The electric arc produces heat and weld can be made with or
without the addition of filler material. Carbon arc welding may be classified as-
(1) Single electrode arc welding, and
(2) Twin carbon electrode arc welding
In single electrode arc welding, an electric arc is struck
between a carbon electrode and the workpiece. Welding may
be carried out in air or in an inert atmosphere. Direct current
straight polarity (DCSP) is preferred to restrict electrode
disintegration and the amount of carbon going into the weld
metal. This process is mainly used for providing heat source
for brazing, braze welding, soldering and heat treating as well
as for repairing iron and steel castings. It is also used for
welding of galvanized steel and copper is as shown in the
fig6.9.
In twin carbon arc welding the arc struck between two
carbon electrodes produces heat and welds the joint. The arc
produced between these two electrodes heats the metal
Fig. 6.9. Principle of carbon arc welding
to the melting temperature and welds the joint after solidification. The power source used is AC
(Alternating Current) to keep the electrodes at the same temperature. Twin-electrode carbon arc welding
can be used for welding in any position. This process is mainly used for joining copper alloys to each other
or to ferrous metal. It can also be used for welding aluminium, nickel, zinc and lead alloys.

FOUNDRY
Introduction:
Foundry is a process of shaping the metal components in their molten stage. It is the also called as metal
casting the shape and size of the metal casting is obtained depends on the shape and size of the cavity
produced in sand mould by using wooden/ metal pattern.
Practical application
1. Casting is the cheapest and most direct way of producing the shape of the component
2. Casting is best suited to work where components required is in low quantity.
3. Complicated shapes having internal openings and complex section variation can be produced quickly
and cheaply by casting since liquid metal can flow into any form/ shape.
Example:
1. Outer casing of all automobile engines.
2. Electric motor housing
3. Bench vice, Irrigation pumps etc.
4. Heavy equipment such as machine beds of lathe, milling machine, shaping, drilling planing machine etc.
can be cast/easily
5. Casting is best suited for composite components
Example.1. steel screw threads in zinc die casting
All conductors into slot in iron armature for electric motor.
Steps in foundry process
The Foundry process involves three steps.
(a) Making the required pattern
(b) Moulding process to produce the cavity in sand using pattern.
(c) Pouring the molten metal into the cavity to get casting.
Classification of foundries
 Steel foundry
 C.I foundry
 Light alloy foundry
 Brass foundry
 Shell moulding foundry
 Die casting foundry (using permanent metal or dies for high volume of low and pressure die)
Pattern:
A pattern is normally a wooden/ metal model or thermosetting plastic which is facsimile of the cast
product to be made, there are many types of pattern and are either one piece, two piece or three piece,
split pattern, loose piece pattern, Gated and match plate pattern etc. Pattern size: Actual casting size
+shrinkage allowance +shake allowance +finish allowance
1. Shrinkage allowance: The liquid metal shrinks during solidification and it contraction to its room
temperature, so that the pattern must be made larger then the casting to provide for total contraction.
2. Finishing allowance: The casting is to be machined at some points then the casting should be provided
with excess metal for machining.

Types of foundry sand
1. Natural sand: Sand containing the silica grains and clay bond as found. It varies in grain size and clay
content. Collected from natural recourses.
2. Synthetic sand: It is an artificial sand obtained by mixing relatively clay free sand, binder (water and
bentonoite). It is better moulding sand as its properties can be easily controlled.
3. Facing sand: It is the fine grade sand used against the face of the pattern and finally governs the
surface finish of the casting.
4. Parting sand: It is fine dry sand + brick dust used to preserve the joint face between the cope and the
drag.
Natural Green sand= sand + clay + moisture
(10 to 15%) (7 to 9%)
Synthetic Green sand= sand + clay + moisture
(5 to 7%) (4 to 8%)
5. Green sand: mouldings is the most common moulding process
5. Dry sand mould: Dry sand mould refer to a mould which is artificially dried before the molten metal is
poured into it. Dry sand moulds are costly, stronger, used for complicated castings, i.e. avoid casting
defects, casting gets smoother surface.
Moulding methods:
 Bench moulding: In this method the moulding is carried out on convenient bench and moulds are
relatively small.
 Floor mouldings: In this method the mouldings is carried out in medium and large moulds are
carried out on the floor.
 Plate mouldings: For large quantity production and for very heavy casting two plates may be used
with pattern.
 Pit moulding: In this method the moulding is carried out in the pits and generally very large
moulds are made.
 Machine mouldings: A machine is used to prepare moulds of small and medium. This method is
faster and gives uniform mouldings
CORE AND CORE MAKING
CORES: Cores are sand blocks they are used to make hollow portion in a casting. It is placed in a mould so
that when molten metal is poured into
the mould. This apart of mould will
remain vacant i.e. the molten metal
will not fill this part of the mould. So
when the mould is broken and the
castings removed a hollow portion will
result in the casting.
Core sand= Moulding sand+
binders (ABC core oil) or sodium
silicate
Core making: Cores are made
separately in a core box made of wood
or metal.

Core binders
1. Water soluble binders (2 t0 4% by weight)
2. Oil binders (1-3% by weight)
3. Pitch and resin binders (1-35 by weight)
The sand is treated with binder to achieve cohesion
Core Baking
The core is baked (hardened) by heating at 150C depends on core size in oven.
This hardening of the core helps to handle and to place the core in the mould.
The core is supported in the mould by projection known as core prints.
NOMENCLATURE OF A MOULD

FOUNDRY TOOLS AND EQUIPMENTS
1. INTRODUCTION
There are large number of tools and equipment used in foundry shop for carrying out different operations
such as sand preparation, molding, melting, pouring and casting. They can be broadly classified as hand
tools, sand conditioning tool, flasks, power operated equipments, metal melting equipments and fettling
and finishing equipments. Different kinds of hand tools are used by molder in mold making operations.
Sand conditioning tools are basically used for preparing the various types of molding sands and core sand.
Flasks are commonly used for preparing sand moulds and keeping molten metal and also for handling the
same from place to place. Power operated equipments are used for mechanizing processes in foundries.
They include various types of molding machines, power riddles, sand mixers and conveyors, grinders etc.
Metal melting equipment includes various types of melting furnaces such as cupola, pit furnace, crucible
furnaces etc. Fettling and finishing equipments are also used in foundry work for cleaning and finishing
the casting. General tools and equipment used in foundry are discussed as under.
2 HAND TOOLS USED IN FOUNDRY SHOP
The common hand tools used in foundry shop are fairly numerous. A brief description of the following
foundry tools used frequently by molder is given as under.
1.Showel: It consists of iron pan with a wooden handle. It can be used for mixing and conditioning the
sand.
Shovel is shown in Fig. 1(b). It consists of an steel pan fitted with a long wooden handle. It is used in
mixing, tempering and conditioning the foundry sand by hand. It is also used for moving and transforming
the molding sand to the container and molding box or flask. It should always be kept clean.
2. Trowels: These are used for finishing flat surfaces and comers inside a mould. Common shapes of
trowels are shown as under. They are made of iron with a wooden handle. Trowels are shown in Fig.
11.1(l, m and n). They are utilized for finishing flat surfaces and joints and partings lines of the mold. They
consist of metal blade made of iron and are equipped with a wooden handle. The common metal blade
shapes of trowels may be
pointed or contoured or
rectangular oriented. The
trowels are basically
employed for smoothing or
slicking the surfaces of
molds. They may also be
used to cut in-gates and
repair the mold surfaces.

3. Lifter: A lifter is a finishing tool used for repairing the mould and finishing the mould sand. Lifter is also
used for removing loose sand from mould.
4. Hand riddle: It is used for ridding of sand to remove foreign material from it. It consists of a wooden
frame fitted with a screen of standard wire mesh at the bottom.

Hand riddle is shown in Fig. 1(a). It consists of a screen of standard circular wire mesh equipped with
circular wooden frame. It is generally used for cleaning the sand for removing foreign material such as
nails, shot metal, splinters of wood etc. from it. Even power operated riddles are available for riddling
large volume of sand.
5.Strike off bar: It is a flat bar, made of wood or iron to strike off the excess sand from the top of a box
after ramming.
Its one edge made beveled and the surface perfectly smooth and plane.
6. Vent wire: It is a thin steel rod or wire carrying a pointed edge at one end and a wooden handle or a
bent loop at the other. After ramming and striking off the excess sand it is used to make small holes,
called vents, in the sand mould to allow the exit of gases and steam during casting.

7. Rammers: Rammers are used for striking the sand mass in the moulding box to pack it closely around
one pattern. Common types of rammers are shown as under.
Rammers are shown in Fig. These are required for striking the molding sand mass in the molding box to
pack or compact it uniformly all around the pattern. The common forms of rammers used in ramming are
hand rammer, peen rammer, floor rammer and pneumatic rammer which are briefly described as
8. Swab: It is a hemp fiber brush used for moistening the edges of sand mould, which are in contact with
the pattern surface, before withdrawing the pattern. It is also used for coating the liquid blacking on the
mould faces in dry sand moulds.
9. Sprue pin: It is a tapered rod of wood or iron, which is embedded in the sand
and later withdrawn to produce a hole, called runner, through which the molten
metal is poured into the mould.
Sprue pin is shown in Fig. It is a tapered rod of wood or iron which is placed or
pushed in cope to join mold cavity while the molding sand in the cope is being
rammed. Later its withdrawal from cope produce a vertical hole in molding
sand, called sprue through which the molten metal is poured into the mould
using gating system. It helps to make a passage for pouring molten metal in
mold through gating system

10. Sprue cutter: It is also used for the same purpose as a sprue pin, but there is a marked difference
between their use in that the cutter is used to produce the hole after ramming the mould. It is in the form
of a tapered hollow tube, which is inserted in the sand to produce the hole.
Strike off bar
Strike off bar (Fig. is a flat bar having straight edge and is made of wood or iron. It is used to strike off or
remove the excess sand from the top of a molding box after completion of ramming thereby making its
surface plane and smooth. Its one edge is made beveled and the other end is kept perfectly smooth and
plane.
Mallet
Mallet is similar to a wooden hammer and is generally as used in carpentry or sheet metal shops. In
molding shop, it is used for driving the draw spike into the pattern and then rapping it for separation from
the mould surfaces so that pattern can be easily withdrawn leaving the mold cavity without damaging the
mold surfaces.
Draw spike
Draw spike is shown Fig. It is a tapered steel rod having a loop or ring
at its one end and a sharp point at the other. It may have screw
threads on the end to engage metal pattern for it withdrawal from the
mold. It is used for driven into pattern which is embedded in the
molding sand and raps the pattern to get separated from the pattern
and finally draws out it from the mold cavity.
Vent rod

Vent rod is shown in Fig. 11.1(g). It is a thin spiked steel rod or wire carrying a pointed edge at one end
and a wooden handle or a bent loop at the other. After ramming and striking off the excess sand it is
utilized to pierce series of small holes in the molding sand in the cope portion. The series of pierced small
holes are called vents holes which allow the exit or escape of steam and gases during pouring mold and
solidifying of the molten metal for getting a sound casting.
Lifters
Lifters are shown in Fig.. They are also known as cleaners or finishing tool which are made of thin sections
of steel of various length and width with one end bent at right angle. They are used for cleaning, repairing
and finishing the bottom and sides of deep and narrow openings in mold cavity after withdrawal of
pattern. They are also used for removing loose sand from mold cavity.
Slicks
Slicks are shown in Fig. 11.1(o, p, q, and r). They are also recognized as small double ended mold finishing
tool which are generally used for repairing and finishing the mold surfaces and their edges after
withdrawal of the pattern. The commonly used slicks are of the types of heart and leaf, square and heart,
spoon and bead and heart and spoon. The nomenclatures of the slicks are largely due to their shapes.

Smoothers
Smothers are shown in Fig. 11.1(s and t). According to their use and shape they are given different names.
They are also known as finishing tools which are commonly used for repairing and finishing flat and round
surfaces, round or square corners and edges of molds.
Spirit level
Spirit level is used by molder to check whether the sand bed or molding box is horizontal or not.
Gate cutter
Gate cutter (Fig. 11.1(v)) is a small shaped piece of sheet metal commonly used to cut runners and
feeding gates for connecting sprue hole with the mold cavity.
Gaggers

Gaggers are pieces of wires or rods bent at one or both ends which are used for reinforcing the
downward projecting sand mass in the cope are known as gaggers. They support hanging bodies of sand.
They possess a length varying from 2 to 50 cm. A gagger is always used in cope area and it may reach up
to 6 mm away from the pattern. It should be coated with clay wash so that the sand adheres to it. Its
surface should be rough in order to have a good grip with the molding sand. It is made up of steel
reinforcing bar.
Spray-gun
Spray gun is mainly used to spray coating of facing materials etc. on a mold or core surface.
Nails and wire pieces
They are basically used to reinforce thin projections of sand in the mold or cores.
Wire pieces, spring and nails
They are commonly used to reinforce thin projections of sand in molds or cores. They are also used to
fasten cores in molds and reinforce sand in front of an in-gate.
Clamps, cotters and wedges
They are made of steel and are used for clamping the molding boxes firmly together during pouring.
FLASKS
The common flasks are also called as containers which are used in foundry shop as mold boxes, crucibles
and ladles.
1. Moulding Boxes
Mold boxes are also known as molding flasks. Boxes used in sand molding are of two types:
(a) Open molding boxes. Open molding boxes are shown in Fig. They are made with the hinge at one
corner and a lock on the opposite corner. They are also known as snap molding boxes which are generally
used for making sand molds. A snap molding is made of wood and is hinged at one corner. It has special
applications in bench molding in green sand
work for small nonferrous castings. The
mold is first made in the snap flask and then
it is removed and replaced by a steel jacket.
Thus, a number of molds can be prepared
using the same set of boxes. As an
alternative to the wooden snap boxes the
cast-aluminum tapered closed boxes are
finding favor in modern foundries. They
carry a tapered inside surface which is
accurately ground and finished. A solid
structure of this box gives more rigidity and
strength than the open type. These boxes
are also removed after assembling the
mould. Large molding boxes are equipped
with reinforcing cross bars and ribs to hold
the heavy mass of sand and support gaggers.
The size, material and construction of the
molding box depend upon the size of the
casting.

(b) Closed molding boxes. Closed molding boxes are shown in Fig. 11.3 which may be made of wood,
cast-iron or steel and consist of two or more parts. The lower part is called the drag, the upper part the
cope and all the intermediate parts, if used, cheeks. All the parts are individually equipped with suitable
means for clamping arrangements during pouring. Wooden Boxes are generally used in green-sand
molding. Dry sand moulds always require metallic boxes because they are heated for drying. Large and
heavy boxes are made from cast iron or steel and carry handles and grips as they are manipulated by
cranes or hoists, etc. Closed metallic molding boxes may be called as a closed rectangular molding box
(Fig. 11.3) or a closed round molding box (Fig. 11.4).
Ladle

It is similar in shape to the crucible which is also made from graphite or steel shell lined with suitable
refractory material like fire clay. It is commonly used to receive molten metal from the melting furnace
and pour the same into the mold cavity. Its size is designated by its capacity. Small hand shank ladles are
used by a single foundry personal and are provided with only one handle. It may be available in different
capacities up to 20 kg. Medium and large size ladles are provided with handles on both sides to be
handled by two foundry personals. They are available in various sizes with their capacity varying from 30
kg to 150 kg. Extremely large sizes, with capacities ranging from 250 kg to 1000 kg, are found in crane
ladles. Geared crane ladles can hold even more than 1000 kg of molten metal. The handling of ladles can
be mechanized for good pouring control and ensuring better safety for foundry personals workers. All the
ladles consist of an outer casing made of steel or plate bent in proper shape and then welded. Inside this
casing, a refractory lining is provided. At its top, the casing is shaped to have a controlled and well
directed flow of molten metal. They are commonly used to transport molten metal from furnace to mold

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