Main report

INVESTIGATION OF MOULDING SAND FOR THE
PRODUCTION OF FERROUS METAL CASTING
BY
OGUNLADE, ABAYOMI OLADELE
MEE/2013/073
AND
SERIKI, SIKIRU AJIBOLA
MEE/2013/078
A PROJECT SUBMITTED IN PARTIAL FULFILMENT OF THE
REQUIREMENTS FOR THE AWARD OF BACHELOR OF
SCIENCE IN MECHANICAL ENGINEERING
OBAFEMI AWOLOWO UNIVERSITY, ILE-IFE, OSUN STATE,
NIGERIA.
MAY, 2018.

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Department of Mechanical Engineering,
Faculty of Technology,
Obafemi Awolowo University,
Ile-Ife, Osun State.
18th May, 2018
The Project Supervisor,
Department of Mechanical Engineering,
Obafemi Awolowo University,
Ile-Ife, Osun State.
Dear Sir,
LETTER OF TRANSMITTAL
In pursuit of your request, we hereby submit this report on “Investigation of moulding sand for
the production of ferrous metal casting” In partial fulfillment of the requirement for the award of
Bachelor of Science (B.Sc.) degree in Mechanical Engineering. Thank you.
Yours faithfully,
OGUNLADE Abayomi Oladele (MEE/2013/073)
SERIKI Sikiru Ajibola (MEE/2013/078)

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CERTIFICATION
This is to certify that this research project ”Investigation of moulding sand for the production of
ferrous metal casting” was carried out by OGUNLADE Abayomi Oladele (MEE/2013/073) and
SERIKI Sikiru Ajibola (MEE/2013/078) for the award of Bachelor of Science degree in
Mechanical Engineering of the Obafemi Awolowo University, Ile-Ife, under the supervision of
Engr. H.A. Owolabi.
……………………………… …………………………….
Engr. H. A. Owolabi Date
Supervisor
……………………………… ………………………………
Dr. D. A. Adetan Date
Head of Department

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DEDICATION
This project is dedicated to the Almighty God.

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ACKNOWLEDGEMENTS
First of all we like to express our gratitude to God Almighty who has given us the opportunity to
go through this B.Sc. programme and to write a report in this regard.
To Engr. H.A. Owolabi, our project supervisor, whom we respect and admire for the excellent
advice and guidance he gave us throughout the entire study of this project.
With a deep sense of appreciation, respect and gratitude, we want to say a big thank you to our
parents, brothers & sisters and friends for their caring attitude and support from the beginning of
the pursuit for B.Sc. degree in Mechanical Engineering to this point.
Lastly, our appreciation goes to all staff of the Department of Mechanical Engineering who
impacts our lives positively and to our colleagues for the belief they have in us.

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ABSTRACT
Foundry engineering is an important aspect of production engineering that deals with production
of metal engineering parts. In achieving good metal casting, properties of sand which affects its
effectiveness for casting was greatly considered. The aim of this project is to investigate the
suitability of some local river sand in the production of ferrous metal castings. The silica sand
used are from three different local rivers located in the south western region of Nigeria; Opa,
Isheri-Oke and Osogbo. The Taguchi L9 (34
) orthogonal array was chosen for the experimental
design of experiment (DOE). The Taguchi experimental approach combines four parameters at
three levels. The parameters considered for this research are; grain fineness number (GFN),
pouring temperature, shakeout Time (SOT) and moisture content.
The GFN, moisture content, clay content, permeability number, green compressive strength,
green shear strength and the elemental composition of Opa, Isheri-Oke and Osogbo were
determined. Castings made from grey cast iron were produced in nine experimental runs for the
casting of rods, hardness and impact strength were tested on the rods using Rockwell testing
machine and Balanced impact testing machine respectively.
The optimum process parameters were determined using the Signal-to-noise ratio with the
casting defects are “higher the better” quality of the type of quality characteristics was used. The
higher the better signal-to-noise ratio was carried out on the nine experimental runs, in which the
optimum levels for the process parameters was concluded to be; GFN- 67, Moisture content- 5%,
Shakeout time- 50minutes and Pouring temperature- 1300°C when hardness was combined with
impact strength, and the optimum levels of the process parameters for impact strength alone was
concluded to be; GFN- 68.27, moisture content- 6%, shakeout time- 50minutes and poring
temperature- 1300°C. A grey cast iron pulley was later cast from the optimum process
parameters in relation to when hardness was combined with the impact strength.

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Table of Contents
COVER PAGE i
LETTER OF TRANSMITTAL ii
CERTIFICATION iii
DEDICATION iv
ACKNOWLEDGEMENTS v
ABSTRACT vi
List of Tables ix
List of Figures x
List of Plates xi
CHAPTER ONE 1
INTRODUCTION 1
1.1 Background of Study 1
1.2 Problem Statement 7
1.3 Objective of the Study 8
1.4 Justification for the Study 8
1.5 Scope of the Study 8
CHAPTER TWO 10
LITERATURE REVIEW 10
2.1 Casting 10
2.2 Sand Casting 11
2.3 Mould Materials 14
2.3.1 Types of moulds 14
2.3.2 Moulding sands: sources, types and ingredients 14
2.3.3 Moulding sands 15
2.3.4 Types of base sands 17
2.3.5 Moulding sand materials 19
2.3.6 Parting compounds 21
2.3.7 Water (Moisture) 21
2.4 Terms in Metal Casting 21
2.5 Foundry Tools and Equipment 23
2.5.1 Hand tools 23
2.5.2 Moulding boxes 26

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2.5.3 Melting equipments: 26
2.5.4 Moulding sand 27
2.6 Review of Past Work on Moulding Sand and Coating 27
2.7 Grey Cast Iron 31
2.8 Mechanical Properties of Metals 32
2.9 Gating System 36
2.9.1 Requirements needed in gating system to achieve free casting defects: 36
2.9.2 Factors controlling the functioning of gating system 38
2.9.3 Elements of gating system 38
2.9.4 Improper gating system design defects 40
2.10 Flat Belt Pulley 40
2.10.1 Types of pulleys for flat belt 40
2.11 Working Principle of Atomic Absorption Spectrometry 41
CHAPTER THREE 45
METHODOLOGY 45
3.1 Collection of Silica Sands 45
3.2 Determination of Some Natural State Properties of the Sand 45
3.3 Preparation of Sand for Experiment and Testing 48
3.3.1 Sieve analysis and determination of grain fineness number (GFN) 51
3.3.2 Determination of some green state properties of the sand 51
3.3.3 Determination of elemental composition in the sands 60
3.4 Design of Experiment 60
3.5 Design of Gating and Feeding System 61
3.5.1 Design of riser (feeder) 61
3.5.2 Design of pouring basin 66
3.5.2 Design of down-runner or sprue 67
3.6 Design of Cast Iron Pulley 71
3.7 Production of the Cast Product 72
3.7.1 Production of pattern 73
3.7.2 Preparation of moulding sand 73
3.7.3 Melting and pouring of molten metal 73
3.7.4 Shakeout of cast product 73
3.8 Mechanical Properties Examination 78

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3.9 Signal-to-Noise Ratio 78
CHAPTER FOUR 82
RESULT AND DISCUSSION 82
4.1 Moisture and Clay Content of the Sands 82
4.2 Sieve Analysis and Determination of Grain Fineness Number of the Sands 82
4.3 Determination of Permeability Number and Green Compressive Strength 82
4.4 Determination of Green Shear Strength of the Sand Samples 88
4.5 Determination of Elemental Composition in the Mould Sands 88
4.6 Determination of Mechanical Properties of the Casting 88
4.7 Experimental Result 100
4.7.1 Signal-to-noise (S/N) ratio calculations 100
4.7.3 Response curves 101
CHAPTER FIVE 109
CONCLUSION AND RECOMMENDATION 109
REFERENCES 111
APPENDIX 114

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List of Tables
Table 1: Typical composition of moulding sand 24
Table 2: Grey iron casting, as per IS: 210-1993 34
Table 3: Control factors and their levels 62
Table 4: Standard orthogonal array-l9 (34
) 63
Table 5: Experimental design 64
Table 6: The value of constant P with corresponding mass 69
Table 7: Standard width of pulley 79
Table 8: Moisture content result for Opa, Isheri-Oke and Osogbo River sands 83
Table 9: Clay content result for Opa, Isheri-Oke and Osogbo River sands 83
Table 10: Sieve analysis for determination of GFN (Opa River sand) 85
Table 11: Sieve analysis for determination of GFN (Isheri-Oke River sand) 86
Table 12: Total metal concentrations (mg/L) in Opa and Isheri-Oke sands 90
Table 13: Total metal concentrations (mg/kg) in Opa and Isheri-Oke sands 91
Table 14: Metal compositions and %concentration (mg/kg) of Osogbo sand 92
Table 15: Hardness and impact result of the casting 94
Table 16: Experimental result 102
Table 17: Signal-to-noise ratio for impact strength 103
Table 18: S/N ratio for hardness combined with Impact strength 104
Table 19: S/N ratio response for impact strength 105
Table 20: Signal-to-noise ratio response for hardness combined with impact strength 106

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List of Figures
Figure 1: Flow-chart of metal casting system 12
Figure 2: Processes in sand casting 13
Figure 3: Foundry tools and equipment 28
Figure 4: Diagram showing the elements of a gating System 37
Figure 5: Solid cast iron pulleys 42
Figure 6: Split cast iron pulley 42
Figure 7: Basic principle of Atomic Absorption Spectrometry 44
Figure 8: Gating system and pulley model 80
Figure 9: Exploded View of Gating System 81
Figure 10: Percentage moisture content against sand location 84
Figure 11: Percentage clay content against sand location 84
Figure 12: Percentage retained against sieve size for Opa sand 87
Figure 13: Percentage retained against sieve size for Isheri-Oke sand 87
Figure 14: Correlation within % concentration in sands 93
Figure 15: A Chart Showing the hardness and impact results of the Casting Experiments 95
Figure 16: A Chart showing the addition of Hardness and Impact for the Casting Experiments 96
Figure 17: Response curves for Impact strength 107
Figure 18: Response curves 108

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List of Plates
Plate 3.1: Collection of sand sample 46
Plate 3.2: Washing of sand to determine clay content 47
Plate 3.3: Sand sample after washing 49
Plate 3.4: Oven drying of sand samples 50
Plate 3.5: Collection of lumps from the sand samples 52
Plate 3.6(a): Set of sieves on a shaker 53
Plate 3.6(b): Pouring of sand into set of sieves 53
Plate 3.7: Ridsdale-Dietert metric standard rammer 55
Plate 3.8: 50mm x 50mm height sample stripped from sample holder 56
Plate 3.9: Ridsdale-Dietert permeability meter 57
Plate 3.10: Ridsdale-Dietert universal sand strength machine 59
Plate 3.11(a): Pattern 74
Plate 3.11(b): Pattern in drag 74
Plate 3.12: Moulds 75
Plate 3.13: Molten metal in crucible pot 76
Plate 3.14: Cast product (Pulley) 77
Plate 3.15: Rockwell Hardness Testing Machine 97
Plate 3.16: Impact Testing Piece 98
Plate 3.17: Balanced impact testing machine 99

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CHAPTER ONE
INTRODUCTION
1.1 Background of Study
A foundry is a place where castings are produced. Casting is a manufacturing process in which a
liquid material is usually poured into a mould, which contains a hollow cavity of the desired
shape, and then allowed to solidify. According to Kalpakjian and Schmid (2012), metal casting
process begins by creating a mould, which is the ‘reverse’ shape of the part needed. The mould is
usually made from sand by placing a model (Pattern) of the object made of wood or metal used
for forming an impression (mould) on the sand. The metal is heated in a furnace until it melts,
and the molten metal is poured into the mould cavity. The liquid takes the shape of cavity, which
is the shape of the part. It is cooled until it solidifies. Finally, the solidified metal part is removed
from the mould.
Sand is used to make moulds for multiple reasons because it can easily withstand the heat of
molten metal, it does not chemically react with the metal and it is permeable enough to allow
gases to escape when the molten metal is poured. Sand is also the principal moulding material in
the foundry shop where it is used for all types of casting, ferrous and non-ferrous alike (Olawale
et al., 2011). Casting is most often used for making complex shapes that would be otherwise
difficult or uneconomical to make by other methods. There are many other methods of shaping
metals, such as machining, forging, welding and hot working.
Edoziuno et al., (2017) investigated the suitability of using river Niger sand (Onitsha deposit)
and Ukpor clay to compose moulding sand. Laboratory Foundry sand tests were carried out on
American Foundry Society (AFS) standard test specimens (50 mm diameter by 50 mm height)
prepared with a Ridsdale laboratory sand rammer, to determine their moulding properties in both

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dry and green conditions. The results of chemical analysis of the sand and the clay samples
indicated that the sand is of high silica content (89.9%) and the clay is rich in both silica and
alumina contents (67.2% and 24.5%) which is an indication of their suitability for use in foundry
mould production and other refractory applications.
Atanda et al., (2012) worked on the effects of bentonite and cassava starch binders on foundry
moulding sand. The two binders were applied separately to silica sand in different proportions
and also as a mixture in different proportions as well. The effects of these various additions on
foundry moulding sand were investigated by conducting out various tests as permeability,
moisture content, green compressive and green shear strength, dry compressive and dry shear
strength as well as the AFS of the sand. The results showed that bentonite had better binding
characteristics than cassava starch but a mixture of both in equal proportions gave a range of
excellent mould properties that could be exploited in making moulds for different weights of
castings.
Bala and Khan (2013), reported on the characterization of beach/river sand for foundry use. Bulk
properties of the sand samples collected were evaluated. The experimental results were analyzed
as per the American Foundry Society (AFS) standard. The analyses show that samples from
Ughelli River, Warri River and Ethiope River could be used effectively in the foundry. The
sample from Lagos bar beach requires to be sieved properly to remove the coarse fractions in
order to make it suitable for foundry use.
Akinbode (1996) carried out an investigation on the properties of termite hills as refractory
material for furnace lining. In his report, he observed that the refractory properties of termite hill
material which include porosity, density, dimensional change and permeability are very similar
to known refractory materials for furnace lining.

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Akinyele and Oyeyemi (2014) looked at the best and effective way of managing the waste
foundry sand. Physical and chemical test were carried out on samples of foundry sand, to know
its usefulness as alternative aggregate in concrete. Fine aggregate in concrete was partially
replaced with foundry sand at 0%, 25%, 50%, 75%, and 100%. Compressive tests were carried
out on sixty samples of concrete cubes of dimension 150 mm x 150 mm x 150 mm and each
twelve samples was used for each aggregate composition. The pure aggregate gave 28 days
concrete strength of 20.79 N/mm2
, while 25% foundry gave 19.62 N/mm2
, other samples gave
results that were very poor due to the presence of large clay particles. It was concluded that
foundry sand can be applied to fine aggregate in concrete up to 25% inclusion.
Jimoh et al., (2015) carried out their research work to provide an insight to the vast availability
of quality and quantity of quarry sands which can be mined for use as foundry sand by the
numerous cottage aluminum industries in Nigeria. Four sand deposits (Ado road, Abo road, Owo
road and Oda road) were mapped out from Akure in Ondo states, South-western Nigeria. The
physical and chemical properties were determined as the bases for evaluation. The presence of
macronutrients such as Ca, Na, Mg, and K in most of the sand samples falls within acceptable
limits. It was concluded that three of the selected sand deposits (Abo, Ado road, and Oda road)
were found suitable for aluminium casting, though all the four sand can be used for ferrous
materials (steel and cast iron). Oda and Owo road have coarse grain sizes making them very
useful in moulding sands in the metal foundries and cement block making.
According to Loto and Akeju (2013), Mechanical test experiments have been performed on the
synthetic mould sand made from the clay and silica sand obtained from lgbokoda in Ondo State,
Nigeria, to determine its durability of use. The synthetic moulding sand was further admixed
with sodium carbonate, cassava flour and coal dust additives in an attempt to enhance the clay

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bonding properties. After each casting, the synthetic moulding sand was re-used and this was
repeated several times. The results showed that the lgbokoda clay-bonded-silica sand has very
good durability up to five times re-use. There was improved mechanical properties/durability
when the additives were used. Castings made during the experimental period were sound. The
additives gave improved bonding property.
Raji (2010), worked on a comparative analysis of grain size and mechanical properties of
aluminium silicon (Al-Si) alloy components produced by different casting methods. This study
was carried out to compare cast microstructures and mechanical properties of aluminium silicon
alloy components cast by various means. For this purpose, sand casting, chill casting and
squeeze casting methods were used to produce similar articles of the same shape and size from
an Al-8%Si alloy. It was observed that the grain size of the microstructures of the cast products
increased from those of squeeze casting through chill casting to sand casting. Conversely, the
mechanical properties of the cast products improved from those of sand casting through chill
casting to squeeze casting. Therefore, squeeze cast products could be used in as cast condition in
engineering applications requiring high quality parts while chill castings and sand castings may
be used in as cast condition for non-engineering applications or engineering applications
requiring less quality parts.
Mohammed et al., (2016), investigated on optimization of sand mould type and melting
parameters to reduce porosity in Aluminium Silicon (Al-Si) alloy castings. The sand mould type
parameters selected for their study were sodium silicate sand mould, dry sand mould, and air-set
sand mould. The melting parameters selected were pouring temperature, holding time and
amount of degasser, keeping the alloy type and other parameters constant. To identify most
influencing process parameters among the selected parameters for aluminum alloy sand castings

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and optimize them to reduced porosity and improve the quality of the castings, Taguchi’s robust
methodology of design of experiment was applied. The experiments conducted show the
influence of selected process parameters on % Porosity of aluminium alloy sand casting. The
optimum level of process parameters obtained were: Pouring temperature – 690°C, Amount of
degasser – 1% of the amount of metal, Holding time – 4 minutes, and Type of mould – Dry sand
mould. Amount of degasser was considered the most significant control factors among the
selected factors and the major contributing factor for reducing porosity in Al-Si alloy castings.
According to Rajkolhe and Khan (2014), Defects in castings lead to rejection of castings and
affect productivity. Blowhole and sand drop are a kind of defect occurring in castings. Several
factors contribute to these defects. Among those, sand particle size, mould hardness, green
compressive strength and permeability are more significant. In the first stage, a set of process
factors that were contributing to these two defects were identified. The identified factors were
analyzed using ‘Design of Experiments’ approach. ‘Signal-to-noise’ ratio was estimated. Robust
design factor values were estimated from the ‘signal-to-noise’ calculations. ANOVA analysis
was done for robust design factor values. In the second stage, optimized factor values were
adopted in practical runs. It was identified that the optimized values had improved the
acceptance percentage from 91.66% to 94.5%.
Ejairu and Falade (2017), investigated on the mechanical properties of sand-cast shafts and
bushing rings. Their study intend to produce shafts and bushing rings with sands obtained from
three different locations in the south western region of Nigeria; Oshogbo, Ilorin and Saki. The
Taguchi L9 (34
) orthogonal array was chosen for the experimental design of experiment. The
Taguchi experimental approach combines four parameters at three levels. The parameters
considered for their research were; grain fineness number, pouring temperature, gating ratio and

6
moisture content. Analysis of variance (ANOVA) was performed to check the adequacy of the
experiment and the effects of the process parameters on the different mechanical properties.
From the result of their analysis obtained, it was seen that the process parameters have
significant effects on the mechanical properties of the cast aluminum and the bushing ring either
individually or combined. The pouring temperature and grain fineness number were the two
significant parameters at 95% level of confidence on the ultimate tensile strength of the cast shaft
and bushing rings. The best mechanical properties inclusive if Ultimate tensile strength, Modulus
of elasticity and %Reduction in area for the casted aluminum shaft was obtained at experiment 7
with pouring temperature of 650o
C and grain fineness number 73.
Xu et al., (2012), worked on development of a kind of coating suitable for green sand steel
casting. The practical application showed that the strength of the coating was high enough with
no crack and no peeling under room temperature after drying the spraying coating, the
performance of the coating for anti cracking was good under high temperature, and the gas
evolution of the coating was low. The usage of the coating appeared to give very good casting
surfaces finish.
Aftab et al., (2015), investigated the effect of different coatings on the surface finish and
hardness of manganese steel castings. Four different moulds were prepared, with the first mould
having no coatings, while the second, third and forth moulds were Linseed-Oil coated, Zircon
coated and Magnesite coated respectively. During the experiment, all the wet coatings were
applied using a spray gun, and each time a pass with the spray was made, the coating was dried
with the oxyacetylene burner torch for 4 to 5 minutes, and then the next pass was made and the
coating were dried subsequently. The pouring rate for all moulds was kept constant and the
pouring time was about 5 seconds. The ambient temperature was around 45˚C. After the filling

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was completed, the moulds were left to cool at the atmospheric temperature for 1 hours, all at a
constant cooling rate. Subsequently, the mould boxes were opened and all the four castings were
placed in a shot blasting machine for 15 minutes on each face. Based on the result obtained from
Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS); it was
concluded that the casting produced from magnesite powder gives the best surface finish. The
greatest hardness values was achieved by the specimens that were casted without any coating and
with zircon coating based on the hardness testing carried out on the casted products on Rockwell
machine.
This project work is looking toward the development of appropriate moulding sand in order to
maximize its effect on the mechanical properties of the ferrous metal casting product (Grey cast-
iron) in order to achieve a high performance of the product using local raw materials. Silica sand
was taken from three different rivers and tested for their natural state properties such as; clay
content, moisture content, grain fineness number etc were determined. Tests were carried out on
the moulding sands in their green states and the properties of the grey cast iron after casting
justified the most appropriate mould sand and the process parameters for casting of grey cast-
iron.
1.2 Problem Statement
Mechanical properties are the most desired characteristics in a casting product and it tends to
show how the material will perform or behave in service. The selection of the most appropriate
moulding sand will serve a means of making decision toward the casting of grey cast iron in
foundries across the nation. The aim of this study is to develop the best moulding sand that will
be most suitable in the production of grey cast-iron in Nigeria and to find out whether

8
mechanical properties depends on mould material, or mould design by using sand casting
process.
1.3 Objective of the Study
The general objective of the study is to develop moulding sand that will be suitable for the sand
casting of grey cast-iron. The specific objectives are to
i. develop moulding sand from silica sand, binders and additives.
ii. investigate the properties of moulding sands developed for the casting of grey cast-
iron.
iii. Casting and evaluation of the mechanical properties of cast produced.
1.4 Justification for the Study
The study of the moulding sand for the sand casting of grey cast-iron from our local raw
material will widen the machinery building base and particularly lead to manufacture of machine
tools in Nigeria. This will help accelerate the country’s industrial development and create
employment. Spare parts of some mechanical and agricultural machines which require cast
components for their repair could be produced.
1.5 Scope of the Study
The study intends to cover the following areas:
i. Development of suitable moulding sand for the sand casting of grey cast-iron.
ii. Considering the process parameters (grain fineness number, moisture content,
shakeout time and pouring temperature) and their level.
iii. Design of a suitable gating system for the casting
iv. Design and produce a pattern for the component to be casted.

9
v. Determination of mechanical properties of the product after casting.
vi. Determining the effect of process parameters on the mechanical properties of the
component produced using Signal-to-noise ratio.

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CHAPTER TWO
LITERATURE REVIEW
2.1 Casting
Casting is a process of forming metallic products by melting the metal, pouring into a cavity
known as the mould and allowing it to solidify; when it is removed from the mould it will be of
the same shape as the mould (Rao, 2000).
Casting is a solidification process, which means the solidification phenomenon controls most of
the properties of the casting. Moreover, most of the casting defects occur during solidification,
such as gas porosity and solidification shrinkage (Rai Technology University (RTU), 2014).
Solidification occurs in two steps: nucleation and crystal growth. In the nucleation stage, solid
particles form within the liquid. When these particles form their internal energy is lower than the
surrounded liquid, which creates an energy interface between the two. The formation of the
surface at this interface requires energy, so as nucleation occurs, the material actually under-
cools, that is it cools below its freezing temperature, because of the extra energy required to form
the interface surfaces. It then recalescences, or heats back up to its freezing temperature, for the
crystal growth stage. Note that nucleation occurs on a pre-existing solid surface, because not as
much energy is required for a partial interface surface, as is for a complete spherical interface
surface. This can be advantageous because fine-grained castings possess better properties than
coarse-grained castings. A fine grain structure can be induced by grain refinement or inoculation,
which is the process of adding impurities to induce nucleation.
All of the nucleation represents a crystal, which grows as the heat of fusion is extracted from the
liquid until there is no liquid left. The direction, rate, and type of growth can be controlled to
maximize the properties of the casting. Directional solidification is when the material solidifies

11
at one end and proceeds to solidify to the other end; this is the most ideal type of grain growth
because it allows liquid material to compensate for shrinkage. Figure 1 shows the flowchart of
metal system.
2.2 Sand Casting
Sand casting, also known as sand molded casting, is a metal casting process characterized by
using sand as the mold material. The term "sand casting" (RTU, 2014) can also refer to an object
produced via the sand casting process. Sand castings are produced in specialized factories called
foundries.
Over 70% of all metal castings are produced via a sand casting process.
Sand casting is relatively cheap and sufficiently refractory even for steel foundry use. In addition
to the sand, a suitable bonding agent (usually clay) is mixed or occurs with the sand. The mixture
is moistened, typically with water, but sometimes with other substances, to develop strength and
plasticity of the clay and to make the aggregate suitable for molding. The sand is typically
contained in a system of frames or mold boxes known as a flask. The mould cavities and gate
system are created by ramming the sand around models, or patterns, or carved directly into the
sand. Processes required in sand casting are shown in Figure 2.
The basic processes in sand casting are (RTU, 2014);
i. Place a pattern in sand to create a mold.
ii. Incorporate the pattern and sand in a gating system.
iii. Remove the pattern.
iv. Fill the mold cavity with molten metal.
v. Allow the metal to cool.
vi. Break away the sand mold and remove the casting.

12
Figure 1: Flow-chart of metal casting system (Divandari, 2000)

13
Figure 2: Processes in sand casting (Rai Technology University book, 2012.)

14
2.3 Mould Materials
The mould material is the one out of which the mould is made, it should be such that casting
should be able to retain its shape till the molten metal has solidified (Divandari, 2000).
There are four main components for making a sand casting mould: base sand, a binder, additives,
and a parting compound.
2.3.1 Types of moulds
The following are types (Divandari, 2000) of moulds used in sand casting:
i. Permanent moulds: They are made up of ferrous metals and alloys (Steel, Grey CI,
etc.), they are employed for casting low melting point materials, they are costly, they are
employed to produce objects smaller in size and they produce casting with better surface
finish, quality and dimensional accuracy.
ii. Temporary refractory moulds: They are made of refractory sands and resins. Since
they are made of refractory sands, the temporary refractory moulds employed for casting
high melting point materials, they are cheaper, they are employed to produce objects
bigger in size and the surface finish, quality and dimensional accuracy of the casting
produced by temporary moulds is poor.
iii. Moulds made of wax, plastic, Plaster of Paris, carbon, ceramics are also employed.
2.3.2 Moulding sands: sources, types and ingredients
The sources (RTU, 2014) of moulding sand include; River beds, sea, lakes and desert.
The types of moulding sand include;
i. Natural sands: It can be used as soon as received from source, it contains binding
material (5-20%), water (5-8%) and considerable amount of organic matter, it can
maintain moisture contain for long time, the finishing obtained on natural sand molds is

15
good, it is cheaper compared to other sand, it has lesser refractoriness and it is employed
for casting CI and non-ferrous metals. Moulds made of natural sand can be easily
repaired and when mixed with bentonite, the properties of the sand get improved and it
gets properties like Synthetic sand.
ii. Synthetic sands: Synthetic sand consists of natural sand with or without clay, binder and
moisture and organic matter is not present in synthetic sand. Synthetic sand is formulated
sand in which formulation is done to impart certain desired properties not possessed by
natural sand, it possesses good refractoriness, high permeability, and uniform grain size
as compared to natural sand and it is more suitable for mass production and mechanized
foundries.
iii. Loam sands: It contains much more clay (50% or more) as compared to ordinary sand
and the ingredients of Loam sand may be fine sand, clay, finely ground refractoriness,
graphite and fibrous reinforcement.
The ingredients used in the production of moulding sand are;
i. Refractory sand grains
ii. Binders
iii. Water (moisture)
iv. Additives
2.3.3 Moulding sands
Moulding sands, also known as foundry sands, are defined by eight characteristics (RTU, 2014):
refractoriness, chemical inertness, permeability, surface finish, cohesiveness, flow-ability,
collapsibility, and availability / cost.

16
i. Refractoriness: This refers to the sand's ability to withstand the temperature of the liquid
metal being cast without breaking down. For example some sands only need to withstand
650 °C (1,202 °F) if casting aluminum alloys, whereas steel needs sand that will
withstand 1,500 °C (2,730 °F). Sand with too low a refractoriness will melt and fuse to
the casting.
ii. Chemical inertness: The sand must not react with the metal being cast. This is especially
important with highly reactive metals, such as magnesium and titanium.
iii. Permeability: This refers to the sand's ability to exhaust gases. This is important because
during the pouring process many gases are produced, such as hydrogen, nitrogen, carbon-
dioxide, and steam, which must leave the mould otherwise casting defects, such as blow
holes and gas holes, occur in the casting. Note that for each cubic centimeter (cc) of water
added to the mould 16,000 cc of steam is produced.
iv. Surface finish: The size and shape of the sand particles defines the best surface finish
achievable, with finer particles producing a better finish. However, as the particles
become finer (and surface finish improves) the permeability becomes worse.
v. Cohesiveness (or bond): This is the ability of the sand to retain a given shape after the
pattern is removed.
vi. Flow-ability: The ability for the sand to flow into intricate details and tight corners
without special processes or equipment.
vii. Collapsibility: This is the ability of the sand to be easily stripped off the casting after it
has solidified. Sands with poor collapsibility will adhere strongly to the casting. When
casting metals that contract a lot during cooling or with long freezing temperature ranges

17
sand with poor collapsibility will cause cracking and hot tears in the casting. Special
additives can be used to improve collapsibility.
viii. Availability/cost: The availability and cost of the sand is very important because for
every ton of metal poured, three to six tons of sand is required. Although sand can be
screened and reused, the particles eventually become too fine and require periodic
replacement with fresh sand.
In large castings (RTU, 2014) it is economical to use two different sands, because the majority
of the sand will not be in contact with the casting, so it does not need any special properties. The
sand that is in contact with the casting is called facing sand, and is designed for the casting on
hand. This sand will be built up around the pattern to a thickness of 30 to 100 mm (1.2 to 3.9 in).
The sand that fills in around the facing sand is called backing sand. This sand is simply silica
sand with only a small amount of binder and no special additives.
2.3.4 Types of base sands
Base sand is the type used to make the mould or core without any binder (RTU 2014).
Because it does not have a binder it will not bond together and is not usable in this state.
i. Silica sand
Silica (SiO2) sand is the sand found on a beach and is also the most commonly used sand. It is
made by either crushing sandstone or taken from natural occurring locations, such as beaches
and river beds. The fusion point of pure silica is 1,760 °C (3,200 °F), however the sands used
have a lower melting point due to impurities. For high melting point casting, such as steels, a
minimum of 98% pure silica sand must be used; however for lower melting point metals, such as
cast iron and non-ferrous metals, a lower purity sand can be used (between 94 and 98% pure).

18
Silica sand is the most commonly used sand because of its great abundance, and, thus, low cost
(therein being its greatest advantage). Its disadvantages are high thermal expansion, which can
cause casting defects with high melting point metals, and low thermal conductivity, which can
lead to unsound casting. It also cannot be used with certain basic metal because it will
chemically interact with the metal forming surface defect. Finally, it causes silicosis in foundry
workers.
ii. Olivine sand
Olivine minerals (so called because of their characteristic green color) are a solid solution of
forsterite (Mg2SiO4) and fayalite (Fe2SiO4). Their physical properties vary with their chemical
compositions; therefore, the composition of the olivine used must be specified to control the
reproducibility of the sand mixture. Care must be taken to calcine the olivine sand before use to
decompose the serpentine content, which contains water. Its main advantage is that it is free from
silica; therefore it can be used with basic metals, such as manganese steels. Other advantages
include a low thermal expansion, high thermal conductivity, and high fusion point. Finally, it is
safer to use than silica, olivine is used for steel casting to control mold dimensions. Olivine is
somewhat less durable than silica, and it is angular sand.
iii. Aluminum silicate
Aluminum silicate (Al2SiO5) occurs in three common forms: kyanite, sillimanite, and andalusite.
All break down at high temperatures to form mullite and silica. Therefore, aluminum silicates for
foundry use are produced by calcining these minerals. Depending on the sintering cycle, the
silica may be present as cristobalite or as amorphous silica. The grains are highly angular. These
materials have high refractoriness, low thermal expansion, and high resistance to thermal shock.
They are widely used in precision investment foundries, often in combination with zircon.

19
2.3.5 Moulding sand materials
According to Rai Technology University (2014), various moulding sand materials are as follows;
i. Binders
Binders are added to base sand to bond the sand particles together (i.e. it is the glue that holds the
mould together). Binders are of many types such as, Clay binders, Organic binders and Inorganic
binders but the mixture of clay and water is the most commonly used binder to provide strength.
There are two major types of clay commonly used: bentonite (Al2O3 4SiO2 nH2O) and kaolinite
or fire clay (Al2O3 2SiO2 2H2O), with the former being the most common. Bentonite can absorb
more water than fire clay which increases its bonding power.
ii. Oil
Oils, such as linseed oil, other vegetable oils and marine oils, used to be used as a binder,
however due to their increasing cost; they have been mostly phased out. The oil also required
careful baking at 100 to 200 °C (212 to 392 °F) to cure (if overheated the oil becomes brittle,
wasting the mould).
iii. Resin
Resin binders are natural or synthetic high melting point gums. The two common types used are
urea formaldehyde (UF) and phenol formaldehyde (PF) resins. PF resins have a higher heat
resistance than UF resins and cost less. There are also cold-set resins, which use a catalyst
instead of a heat to cure the binder. Resin binders are quite popular because different properties
can be achieved by mixing with various additives. Other advantages include good collapsibility,
low gassing, and they leave a good surface finish on the casting. MDI (methylene diphenyl
diisocyanate) is also a commonly used binder resin in the foundry core process.

20
iv. Sodium Silicate
Sodium silicate [Na2SiO3 or (Na2O)(SiO2)] is a high strength binder used with silica moulding
sand. To cure the binder carbon dioxide gas is used, which creates the following reaction:
Na2 O (SiO2) + CO2 Na2 CO3 + 2SiO2 + Heat
The advantage to this binder is that it can be used at room temperature and it's fast. The
disadvantage is that its high strength leads to shakeout difficulties and possibly hot tears in the
casting.
v. Additives
Additives are added to the molding components to improve: surface finish, dry strength,
refractoriness, and "cushioning properties". Up to 5% of reducing agents, such as coal powder,
pitch, creosote, and fuel oil, may be added to the molding material to prevent wetting (prevention
of liquid metal sticking to sand particles, thus leaving them on the casting surface), improve
surface finish, decrease metal penetration, and burn-on defects. These additives achieve this by
creating gases at the surface of the mold cavity, which prevent the liquid metal from adhering to
the sand. Reducing agents are not used with steel casting, because they can carburize the metal
during casting. Up to 3% of "cushioning material", such as wood flour, saw dust, powdered
husks, peat, and straw, can be added to reduce scabbing, hot tear, and hot crack casting defects
when casting high temperature metals. These materials are beneficial because burn-off when the
metal is poured creating voids in the mold, which allow it to expand. They also increase
collapsibility and reduce shakeout time.

21
2.3.6 Parting compounds
To get the pattern out of the mold, prior to casting, a parting compound is applied to the pattern
to ease removal. They can be a liquid or a fine powder (particle diameters between 75 and 150
micrometers (0.0030 and 0.0059 in). Common powders include talc, graphite, and dry silica;
common liquids include mineral oil and water-based silicon solutions. The latter are more
commonly used with metal and large wooden patterns.
2.3.7 Water (Moisture)
Clay acquires its bonding action only in the presence of the required amount of moisture. When
water is added to clay, it penetrates the mixture and forms a microfilm, which coats the surface
of each flake of the clay. The amount of water used should be properly controlled. 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.
A typical composition of sand, clay and moisture in moulding sand is shown in Table1.
2.4 Terms in Metal Casting
(Rao, 2001) define the following casting terms
i. Flask: A moulding flask is one which holds the sand mould intact. Depending upon the
position of the flask in the mould structure it is referred to by various names such as drag-
lower moulding flask, cope-upper moulding flask and cheek-intermediate moulding flask
used in three piece moulding. It is made up of wood for temporary application and more
generally of metal for long-term use.
ii. Pattern: Pattern is a replica of the final object to be made with some modifications. The
mould cavity is made with the help of the pattern.

22
iii. Parting Line: This is the dividing line between the two moulding flasks that make up the
sand mould. In split pattern it is also the dividing line between the two halves of the
pattern.
iv. Bottom Board: This is a board normally made of wood which is used at the start of the
mould making. The pattern is first kept on the bottom board, sand is sprinkled on it and
then the ramming is done in the drag.
v. Facing Sand: The small amount o f carbonaceous material sprinkled on the inner surface
of the moulding cavity to give a better finish of the castings.
vi. Moulding Sand: It is a freshly prepared refractory sand material used for making the
mould cavity. It is a mixture of silica, clay and moisture in appropriate proportion to get
the desired result and it surround the pattern while making the mould.
vii. Backing Sand: It is what constitutes the most of the refractory material; found in the
mould. This is made up of used and burnt sand.
viii. Core: It is used for making hollow cavity in the mould.
ix. Pouring Basin: This is a small funnel shaped cavity at the top of the mould into which the
molten metal is poured.
x. Sprue: The passage through which the molten metal from the pouring basin reaches the
mould cavity. In most cases it controls the flow of metal into the mould.
xi. Runner: The passage-ways in the parting plane through which molten metal flow is
regulated before they reach the mould cavity.
xii. Gate: The actual entry point through which molten metal enters mould cavity
xiii. Chaplet: There are used to support cores inside the mould cavity to take care of its own
weight and overcomes the metallostatic forces.

23
xiv. Chill: These are metallic objects which are placed in the mould to increase the cooling
rate of casting to provide uniform or desired cooling rate.
xv. Riser: It is a reservoir of molten metal provided in the casting so that hot metal can flow
back into the cavity when there is a reduction in volume of metal due to solidification.
2.5 Foundry Tools and Equipment
According to Namsheed et al. (Ma’din Polytechnic College, 2015) the foundry tools and
equipments are divided into the following five groups: (1) Hand tools (2) Moulding boxes (3)
Moulding machines (4) Melting equipments (5) pouring equipments.
2.5.1 Hand tools
Some of the hand tools used in foundry are as follows;
i. Shovel: A shovel consists of a square pan fitted with a wooden handle. It is used for mixing
and for moving the sand from one place to another in the foundry.
ii. Riddle: A riddle has standard wire mesh fixed into a circular or square wooden frame. It is
used for cleaning the moulding sand. The riddle is specified by the diameter of the frame and the
mesh number.
iii. Vent rod: A vent rod is similar to a knitting needle. It has pointed edge at one end and a
handle at the other end. It is used to pierce holes in the rammed sand to provide artificial vents
which permit the easy escape of steam and gases generated by the hot metal in contact with the
sand.
iv. Slick: A slick is a double ended tool having a flat on one end and a spoon on the other. This
tool is also made in a variety of other shapes and is used for repairing and finishing the mould
surfaces after the pattern is withdrawn.

24
Table 1: Typical composition of moulding sand (Ma’din Polytechnic College, 2015)
Molding Sand Constituent Weight (%)
Silica sand 92
(Sodium Bentonite) 8
Clay Water 4

25
v. Lifter: A lifter is made of thin sections of steel of various width and lengths with one end bent
at right angles. It is used for smoothing and cleaning out depressions in the mould.
vi. Swab: A simple swab is a small brush having long hemp fibers. A bulb swab has a rubber
bulb to hold the water and a softer hair brush at the open end. It is used for moistening the sand
around the edge before pattern is removed.
vii. Bellow: The hand operated bellow is used to blow loose particles of sand from the cavities
and surface of the sand.
viii. Trowel: The trowels consist of a metal blade with a wooden handle. The small trowels of
various shapes are used for finishing and repairing mould cavities as well as for smoothing over
the parting surface of the mould.
ix. Gate cutter: A gate cutter is a U-shaped piece of thin sheet. It is used for cutting a shallow
through in the mould to act as a passage for the hot metal.
x. Draw spike: A draw spike is a pointed steel rod, with a loop at one end; it is driven into a
wooden pattern to hold it when the sand is withdrawn. The draw screw is similar in shape but
threaded on the end to engage metal patterns.
xi. Strike-off bar: A strike-off bar a straight bar of wood or steel usually of rectangular cross
section. It is used to strike off excess sand to provide a level and smooth surface.
xii. Mallet: A raw hide mallet is used to loosen the pattern in the mould so that it can be
withdrawn easily.
xiii. Gaggers: The gaggers (also called lifters) are iron rods bent at one end or both ends. It is
used for reinforcement of sand in the top part of a moulding box and to support hanging bodies
of sand.

26
xiv. Clamps: The clamps are used for holding the cope and drag of the mould so that the cope
should not rise when the molten metal is poured into the mould.
xv. Hammer: Hammers are used to strike a job or a tool. They are made of forged steel of
various sizes and shapes to suit various purposes. A hammer consists of 4 parts namely, peen,
head, eye and face. The eye is made oval or elliptical inside in shape and accommodate the
handle. Hammers are classified according to the shape and peen.
(a) Ball peen hammer: This is the most common hammer. The peen has a shape of a ball
which is hardened and polished; size varies from 0.11 to 0.91 Kgs.
(b) Cross peen hammer: This is similar to ball peen hammer in shape and size except
the peen which is across the shaft or eye.
(c) Straight peen hammer: This hammer has a peen straight with the shaft or parallel to
the axis of the shaft.
Some foundry tools and equipments are shown in Figure 3 below.
2.5.2 Moulding boxes
The sand moulds are prepared in specially constructed boxes called flasks (Ma’din Polytechnic
College, 2015), which are open at top and bottom. They are made in two parts, held in alignment
by dowel pins. The top part is called the cope and lower part is called drag. In the flask is made
in three parts, the intermediate part is called a cheek.
2.5.3 Melting equipments:
According to Ma’din Polytechnic College (2015), Equipment meant for melting in the foundry
are;

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i. Cast iron/Ferrous metal-Cupola furnace, electric furnace, rotary furnace. Steel -
Open hearth furnace, electric & Bessemer converter.
ii. Non ferrous metal - Crucible furnace, rotary furnace, Electric furnace.
2.5.4 Moulding sand
The principle material used in making a mould is sand (Ma’din Polytechnic College, 2015). The
sand is defined as the granular particles resulting from the breakdown of rocks. Quartz and other
silica rocks are the source of silica sand which is commonly used for moulding. The silica sand is
found in nature on the bottoms and banks of rivers, lakes and larger bodies of water. Good
moulding sand contains the following ingredients:-
i. Silica sand- 80.80%
ii. Alumina- 14.9%
iii. Iron oxide- 1.3%
iv. Combined water- 2.5%
v. Other inert materials- 1.5%
2.6 Review of Past Work on Moulding Sand and Coating
Ademoh and Abdullahi (2008) investigated the effect of the variation of moisture content on the
properties of Nigeria gum Arabic bonded foundry sand moulds. They showed that sand bonded
with powdered gum Arabic gave stronger bonds than that of with pre-solutioned gum Arabic
pointing out the amount of moisture, in gum Arabic could have significant effects on bonding
performance of material. They also noted that the amount of moisture is directly related to types
sand nature of binder used for the production of synthetic sand. They concluded that high
amounts of added water to gum Arabic bonded moulding sand caused high moisture content in

28
Figure 3: Foundry tools and equipment (Ma’din Polytechnic College Book, 2015)

29
moulds that caused weakening of bond strength and adversely affect other mechanical properties.
Atanda et al., (2012) investigated the effects of Bentonite and Cassava starch binders on foundry
moulding sand. The two binders were applied separately to silica sand in different proportions
and also as a mixture in different proportions as well. The effects of these various additions on
foundry moulding sand were investigated by conducting out various tests as permeability,
moisture content, green compressive and green shear strength, dry compressive and dry shear
strength as well as the AFS of the sand. Their results showed that bentonite had better binding
characteristics than cassava starch but a mixture of both in equal proportions gave a range of
excellent mould properties that could be exploited in making moulds for different weights of
castings. Permeability for the two binders decreased as the quantity of binder increased.
Sand is used to make moulds for multiple reasons because it can easily withstand the heat of
molten metal, it does not chemically react with the metal and it is permeable enough to allow
gases to escape when the molten metal is poured. Sand is also the principal moulding material in
the foundry shop where it is used for all types of casting, ferrous and non-ferrous alike.
Ibitoye et al (2014) carried experimental investigations on how to determine the influence of
cement-silica ratio on the moulding properties of Portland cement bonded sand. Test specimens,
comprising silica sand and additives, namely wood flour and dextrin, as well as molasses, with
varying cement to silica sand ratio (RCS), was prepared. The specimens were subjected to tests
in accordance with American Foundrymen's Society (AFS) standard procedure to determine
properties such as bulk density, mould hardness, permeability, compression strength and shear
strength. Their findings revealed that RCS and additives have significant effects on all properties
developed in the moulding sand. It was concluded that as RCS increases, the bulk density, mould
hardness, green compression strength and shear strength increases while permeability and shatter

30
index decreases. However, RCS of 0.105 gives suitable properties for moulding work meant for
iron castings.
Edoziuno et al., (2017) investigated the suitability of using river Niger sand (Onitsha deposit) and
Ukpor clay to compose moulding sand. Laboratory Foundry sand tests were carried out on
American Foundry Society (AFS) standard test specimens (50mm diameter by 50mm height)
prepared with a ridsdale laboratory sand rammer, to determine their moulding properties in both
dry and green conditions. The results of chemical analysis of the sand and the clay samples
indicated that the sand is of high silica content (89.9%) and the clay is rich in both silica and
alumina contents (67.2% and 24.5%) which is an indication of their suitability for use in foundry
mould production and other refractory applications.
Akinbode (1996) carried out an investigation on the properties of termite hills as refractory
material for furnace lining. In his report, he observed that the refractory properties of termite hill
material which include porosity, density, dimensional change and permeability are very similar
to known refractory materials for furnace lining.
Xu et al., (2012), worked on development of a kind of coating suitable for green sand steel
casting. The practical application showed that the strength of the coating was high enough with
no crack and no peeling under room temperature after drying the spraying coating, the
performance of the coating for anti cracking was good under high temperature, and the gas
evolution of the coating was low. The usage of the coating appeared to give very good casting
surfaces finish.
Aftab et al., (2015), investigated the effect of different coatings on the surface finish and
hardness of manganese steel castings. Four different moulds were prepared, with the first mould

31
having no coatings, while the second, third and forth moulds were Linseed-Oil coated, Zircon
coated and Magnesite coated respectively. During the experiment, all the wet coatings were
applied using a spray gun, and each time a pass with the spray was made, the coating was dried
with the oxyacetylene burner torch for 4 to 5 minutes, and then the next pass was made and the
coating were dried subsequently. The pouring rate for all moulds was kept constant and the
pouring time was about 5 seconds. The ambient temperature was around 45˚C. After the filling
was completed, the moulds were left to cool at the atmospheric temperature for 1 hours, all at a
constant cooling rate. Subsequently, the mould boxes were opened and all the four castings were
placed in a shot blasting machine for 15 minutes on each face. Based on the result obtained from
Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS); it was
concluded that the casting produced from magnesite powder gives the best surface finish. The
greatest hardness values was achieved by the specimens that were casted without any coating and
with zircon coating based on the hardness testing carried out on the casted products on Rockwell
machine.
2.7 Grey Cast Iron
Cast iron is generally obtained by re-melting pig iron with coke and limestone in a furnace
known as cupola (Khurmi and Gupta, 2005).It is primarily an alloy of iron and carbon. The
carbon contents in cast iron vary from 1.7 per cent to 4.5 percent. It also contains small amounts
of silicon, manganese, phosphorous and sulphur. The carbon in a cast iron is present in either of
the following two forms: 1.Free carbon or graphite, and 2.Combined carbon or cementite.
According to Khurmi and Gupta (2005) grey colour is due to the fact that the carbon is present in
the form of free graphite. It has a low tensile strength, high compressive strength and no
ductility. It can be easily machined. A very good property of grey cast iron is that the free

32
graphite in its structure acts as a lubricant. Due to this reason, it is very suitable for those parts
where sliding action is desired. The grey iron castings are widely used for machine tool bodies,
automotive cylinder blocks, heads, housings, fly-wheels, pipes and pipe fittings and agricultural
implements.
Grey cast-iron haves the following compositions:
Carbon = 3 to 3.5%; Silicon = 1 to 2.75%; Manganese= 0.40 to 1.0%; Phosphorous = 0.15 to
1%; Sulphur = 0.02 to 0.15%; and the remaining is iron.
According to Indian standard specifications (IS: 210 – 1993), the grey cast iron is designated by
the alphabets ‘FG’ followed by a figure indicating the minimum tensile strength in MPa or
N/mm2
.For example, ‘FG 150’ means grey cast iron with 150MPa or N/mm2
as minimum tensile
strength. Table 2 shows seven recommended grades of grey cast iron with their tensile strength
and Brinell hardness number (B.H.N).
2.8 Mechanical Properties of Metals
The mechanical properties of the metals are those which are associated with the ability of the
material to resist mechanical forces and load (Khurmi and Gupta, 2005). These mechanical
properties of the metal include strength, stiffness, elasticity, plasticity, ductility, brittleness,
malleability, toughness, resilience, creep and hardness. The properties as follows:
i. Strength: It is the ability of a material to resist the externally applied forces without breaking
or yielding. The internal resistance offered by a part to an externally applied force is called
stress.
ii. Stiffness: It is the ability of a material to resist deformation under stress. The modulus of
elasticity is the measure of stiffness.

33
iii. Elasticity: It is the property of a material to regain its original shape after deformation when
the external forces are removed. This property is desirable for materials used in tools and
machines. It may be noted that steel is more elastic than rubber.
iv. Plasticity: It is property of a material which retains the deformation produced under load
permanently. This property of the material is necessary for forgings, in stamping images on coins
and in ornamental work.
v. Ductility: It is the property of a material enabling it to be drawn into wire with the application
of a tensile force. A ductile material must be both strong and plastic. The ductility is usually
measured by the terms, percentage elongation and percentage reduction in area. The ductile
materials commonly used in engineering practice (in order of diminishing ductility) are mild
steel, copper, aluminium, nickel, zinc, tin and lead.
vi. Brittleness: It is the property of a material opposite to ductility. It is the property of breaking
of a material with little permanent distortion. Brittle materials when subjected to tensile loads
snap off without giving any sensible elongation. Cast iron is a brittle material.
vii. Malleability: It is a special case of ductility which permits materials to be rolled or
hammered into thin sheets. A malleable material should be plastic but it is not essential to be so
strong. The malleable materials commonly used in engineering practice (in order of diminishing
malleability) are lead, soft steel, wrought iron, copper and aluminium.
viii. Toughness: It is the property of a material to resist fracture due to high impact loads like
hammer blows. The toughness of the material decreases when it is heated. It is measured by the
amount of energy that a unit volume of the material has absorbed after being stressed up to the
point of fracture. This property is desirable in parts subjected to shock and impact loads.

34
Table 2: Grey iron casting, as per IS:210-1993. (Khurmi and Gupta, 2005)
IS Designation Tensile Strength (Mpa) Brinell hardness number(B.H.N)
FG 150 150 130 to 180
FG 200 200 160 to 220
FG 220 220 180 to 220
FG 260 260 180 to 230
FG 300 300 180 to 230
FG 350 350 207 to 241
FG 400 400 207 to 270

35
ix. Machinability: It is the property of a material which refers to a relative case with which a
material can be cut. Machinability of a material can be measured in a number of ways such as
comparing the tool life for cutting different materials or thrust required to remove the material at
some given rate or the energy required to remove a unit volume of the material. It may be noted
that brass can be easily machined than steel.
x. Resilience: It is the property of a material to absorb energy and to resist shock and impact
loads. It is measured by the amount of energy absorbed per unit volume within elastic limit. This
property is essential for spring materials.
xi. Creep: When a part is subjected to a constant stress at high temperature for a long period of
time, it will undergo a slow and permanent deformation called creep. This property is considered
in designing internal combustion engines, boilers and turbines.
xii. Fatigue: When a material is subjected to repeated stresses, it fails at stresses below the yield
point stresses. Such type of failure of a material is known as fatigue. The failure is caused by
means of a progressive crack formation which are usually fine and of microscopic size. This
property is considered in designing shafts, connecting rods, springs, gears, etc.
xiii. Hardness: It is a very important property of the metals and has a wide variety of meanings.
It embraces many different properties such as resistance to wear, scratching, deformation and
machinability etc. It also means the ability of a metal to cut another metal. The hardness is
usually expressed in numbers which are dependent on the method of making the test. The
hardness of a metal may be determined by the following tests:
(a) Brinell hardness test,
(b) Rockwell hardness test,

36
(c) Vickers hardness (also called Diamond Pyramid) test, and
(d) Shore scleroscope.
2.9 Gating System
The term gating system refers to all passageways through which the molten metal passes to enter
the mould cavity (Ahmed, 2015).The elements of a gating system are;
i. Pouring basin, ii. Sprue, iii. Runner, iv. Gates, and v. Risers
The elements of a gating system are shown is Figure 4.
2.9.1 Requirements needed in gating system to achieve free casting defects:
According to Ahmed (2015), the requirements for gating system need to achieve a free casting
defects are highlighted below;
i. The mould should be completely filled in the smallest time possible without having to rise
metal temperature.
ii. The metal should flow smoothly into the mould.
iii. The unwanted material slag should not be allowed to enter the mould cavity.
iv. The metal entry into the mould cavity should be controlled.
v. A proper thermal gradient be maintained.
vi. Metal flow should be maintained to avoid erosion.
vii. Ensure that enough molten metal reaches the mould cavity.
viii. The gating system should be economical and easy to implement and remove after casting
solidification.
ix. The casting yield should be maximized.

37
Figure 4: Diagram showing the elements of a gating System (Ahmed, 2015)

38
2.9.2 Factors controlling the functioning of gating system
The factors that control the functioning of gating system (Ahmed, 2015) are as follows;
i. Type of pouring equipment, such as ladles, pouring basin etc.
ii. Temperature/Fluidity of molten metal.
iii. Rate of liquid metal pouring.
iv. Type and size of sprue.
v. Type and size of runner.
vi. Size, number and location of gates connecting runner and casting.
vi. Position of mould during pouring and solidification.
2.9.3 Elements of gating system
The elements of gating system (Ahmed, 2015) are discussed as follows;
i. Pouring basin
A pouring basin makes it easier for the ladle or crucible operator to direct the flow of metal from
crucible to sprue. It also help in maintaining the required rate of liquid metal flow and separating
dross, slag etc., from metal before it enters the sprue and as well reduces turbulence at the sprue
entrance.
ii. Sprue
A sprue feeds metal to runner which in turn reaches the casting through gates. A sprue is tapered
with its bigger end at top to receive the liquid metal, and the smaller end is connected to runner.
iii. Gates
A gate is a channel which connects runner with the mould cavity and through which molten
metal flows to fill the mould cavity. A small gate is used for a casting which solidifies slowly
and big gate is used for casting which solidifies fast. A gate should not have sharp edges as they

39
may break during pouring and sand pieces thus may be carried with the molten metal in the
mould cavity. The types of gates used in mould sand are; Top-gate, Bottom-gate and Parting line
side-gate
(a) Top gate:
A top gate is made in the cope portion of the mould. In a top gate the molten metal
enters the mould cavity from the top. Top gate involves high turbulence and sand
erosion and produces poor casting surfaces.
(b) Bottom gate:
A bottom gate is made in the drag portion. In a bottom gate the liquid metal fills
rapidly the bottom portion of the mould cavity and rises steadily and gently up the
mould walls. As comparison to top gate, bottom gate involves little turbulence and
sand erosion. Bottom gate produces good casting surfaces. If freezing takes place at
the bottom, it could choke off the metal flow before the mould is full. Bottom gate
creates an unfavourable temperature gradient and makes it difficult to achieve
directional solidification.
(c) Parting line side gate:
Middle or side or parting gating systems combine the characteristics of top and
bottom gating systems. Gate is provided along the parting line such that some portion
of the mould cavity will be below the parting line and some portion will be above it.
The cavity below the parting line will be filled by assuming top gating and the cavity
above the parting line will be filled by assuming bottom gating.

40
iv. Runner
Runner is a horizontal plane which connects the sprue to gate. The runner should be filled with
molten metal to avoid slag entering to cavity.
2.9.4 Improper gating system design defects
Some defects that occur during improper gating system (AFS, 2015) design are; Oxidation of
metal, Cold shuts, Mould erosion, Shrinkages, Porosity, Misruns and Penetration of liquid metal
into mould walls.
2.10 Flat Belt Pulley
Pulleys are used to transmit power from one shaft to another by means of flat belts (Khurmi and
Gupta, 2005), V-belts or ropes. Since the velocity ratio is the inverse ratio of the diameters of
driving and driven pulleys, therefore the pulley diameters should be carefully selected in order to
have a desired velocity ratio. Pulleys must be in perfect alignment in order to allow the belt to
travel in a line normal to the pulley faces. Pulleys may be made from materials such as; cast iron
cast steel or pressed steel, wood and paper. The cast materials should have good friction and
wear characteristics. The pulleys made of pressed steel are lighter than cast pulleys, but in many
cases they have lower friction and may produce excessive wear.
2.10.1 Types of pulleys for flat belt
The various types of pulleys for flat belts are as follows:
1. Cast iron pulleys, 2. Steel pulleys, 3. Wooden pulleys, 4. Paper pulleys, and 5. Fast and
loose pulleys. Cast-Iron pulleys will be discussed for the purpose of this project work.

41
i. Cast-iron pulleys
The pulleys are generally made of cast iron, because of their low cost. The rim is held in placeby
web from the central boss or by arms or spokes. The arms may be straight or curved as shown in
Figure 5 and the cross-section is usually elliptical.
When a cast pulley contracts in the mould, the arms are in a state of stress and very liable to
break. The curved arms tend to yield rather than to break. The arms are near the hub.
The cast iron pulleys are generally made with rounded rims. This slight convexity is known as
crowning. The crowning tends to keep the belt in centre on a pulley rim while in motion. The
crowning may be 9 mm for 300 mm width of pulley face.
The cast iron pulleys may be solid as shown in Figure 5 or split type as shown in Figure 6.
When it is necessary to mount a pulley on a shaft which already carrying pulleys etc. or have it
sends swelled, it is easier to use a split-pulley. There is a clearance between the faces and the two
halves are readily tightened upon the shafts by the bolts as shown in Figure 6. A sunk key is used
for heavy drives.
2.11 Working Principle of Atomic Absorption Spectrometry
The Atomic absorption spectrometric technique makes use of the flame as the atomizer. The
sample solution is aspirated into the flame and the sample element is converted into atomic
vapour, the flame thus contains atoms of the element. Some are thermally excited by the flame
but most remain in the ground state where they can absorb radiations given off by a special
‘source’ made from that element. The wavelength of radiation given off by the source is the
same as those absorbed by the atoms in the flame. This absorption follows Beer-Lambert’s law
which states the absorbance to be directly proportional to the path length in the flame and to the
concentration of atomic vapour in the flame.

42
Figure 5: Solid cast iron pulleys (Khurmi and Gupta, 2005)
Figure 6: Split cast iron pulley (Khurmi and Gupta, 2005)

43
Both of these variables are difficult to determine but the path length can be held constant and the
concentration of atomic vapour in the flame is directly proportional to the concentration of the
analyte in the solution being aspirated into the flame(Price, 1980).The basic principles of atomic
absorption spectrometry are illustrated in Figure 7 (Price, 1980).

44
Figure 7: Basic principle of Atomic Absorption Spectrometry (Price, 1980)

45
CHAPTER THREE
METHODOLOGY
3.1 Collection of Silica Sands
Silica sands were collected from three locations in the south western region of Nigeria; Osogbo
River (Osun State), Ogun River (Isheri-Oke, Ogun State) and Opa River (Ile-Ife, Osun State).
The process of collecting sand sample at Opa is shown in Plate 3.1.
3.2 Determination of Some Natural State Properties of the Sand
i. Clay Content
AFS clay content includes all particles finer than 20 microns in size, whether they are clay
particles, silt or organic matter, (Jain, 2003).
The materials used for this test are; base sand, sodium hydroxide (NaOH) solution and distilled
water. The apparatus used for this experiment are; wash bottle, measuring jar, mechanical stirrer
and siphon tube.
100 g of base sand in a wash bottle was taken and 475 mL of distilled water and 25 mL of NaOH
solution was added to it. The mixture was stirred using the mechanical stirrer for about 5
minutes, distilled water was added to make up the level to 15.24 cm height. The mixture was
stirred again for 2 minutes. The content of the bottle was allowed to settle down. 12.7 cm level of
unclean water was siphon out using a standard siphon (a tube used to convey liquid upwards
from a reservoir and then down to a lower level of its own accord), Plate 3.2 shows the sand
sample during its first wash. Distilled water was added again up to 15.24 cm height and the
content was stirred again. The mixture was allowed to settle down for 5minutes. 12.7 cm level of
water was siphon out from the bottom of the bottle. The procedure was repeated for 3-4 times till

46
Plate 3.1: Collection of sand sample

47
Plate 3.2: Washing of sand to determine clay content

48
the water becomes clear in the wash bottle (as shown in Plate 3.3). The wet sand was transferred
from the bottle into a tray and was dried in an oven at 100o
C to remove moisture. The dry sand
weight will accurately be noted. The calculation to find the percentage of clay is as follows.
W1= Weight of sand in grams= 100 g
W2 = Weight of dried sand in grams
Clay content = w1-w2 in grams
% of clay =
( )
*100% (3.1)
ii. Moisture Content
50 g of the moist sand sample was measured using digital weighing scale and was oven dried as
shown in Plate 3.4 at a temperature of 100o
C for 2 hours after which all the moisture in the sand
was evaporated in the moist sand. The sample of the dried sand was then weighed. The weight
difference between the initial and new weight were measured to give the moisture content in
gram and this weight difference was expressed in percentage of moisture present in the sand. The
calculation to find the percentage of water (or moist) in the sand is;
W1 = Weight of moist sand in grams
W2= Weight of dried sand in grams
Moist content = w1 - w2 in grams
% Moisture content = ∗ 100% (3.2)
3.3 Preparation of Sand for Experiment and Testing
Impurities such as metallic objects, stones, hard lumps and other unwanted objects was removed
from the various silica sands by sorting and washing the three sands differently. The washed

49
Plate 3.3: Sand sample after washing

50
Plate 3.4: Oven drying of sand samples

51
silica sands were sun dried for 2-3 days to remove free water from it. The process of sun drying
and sorting out of lumps and foreign materials is shown in Plate 3.5.
3.3.1 Sieve analysis and determination of grain fineness number (GFN)
Sieve analysis was performed using British standard (BS) with the aid of mechanical sieve
shaker shown in Plate 3.6(a) using the following sieve sizes: 1000 , 850 , 710 , 500 ,
425 , 355 , 212 , 180 , 150 , 70 and pan. 50 g of dry sand (as shown in Plate
3.6b) was weighed and was allowed to passed through the above serial sieve and shaken for 15
minutes. After been shaken for 15 minutes, the sieves was removed, and the top sieve was
removed first followed by the remaining sieves, the quantity of the sand remaining on each sieve
was then weighed. The percentage of sample weight retained on each sieve was calculated. Each
percent weight was multiplied by the multiplying factor of each sieve mesh to give the products.
The total product was divided by the total sand percentage retained on the sieve to give the AFS
grain fineness number (GFN).
GFN = (3.3)
Where
Q = sum of product of percentage sand retained in sieves and Corresponding multiplier.
P = sum of percentage of sand retained in sieves.
3.3.2 Determination of some green state properties of the sand
i. Permeability
The AFS (American Foundry Men Society) definition of permeability is “the number obtained
by passing 2000 cm3
of air through a standard specimen under a pressure of 10 gm/cm2
for a
given time in minutes”.

52
Plate 3.5: Collection of lumps from the sand samples

53
Plate 3.6(a): Set of sieves on a shaker
Plate 3.6(b): Pouring of sand into set of sieves

54
The materials used for this test are sand, clay (bentonite) and water. The Apparatus used in
testing for this property are; Sand rammer, Permeability meter, Electronic weighing scale,
stripper, stop watch, measuring jar, specimen tube, specimen tube cup.
The dry mixed silica sand was added with required proportions of water and wet mixed for 2
minutes, to get a homogeneous mixture. The correct weight of 150-200 grams of the mixture was
determined by trial and error method. The 150-200 grams sand mixture was filled into the
specimen tube and ram thrice using sand rammer as shown in Plate 3.7. The tolerance limit
provided at the top end of the rammer was used for checking the specimen size (that is; if the top
end of the rammer is within the tolerance limit, the correct specimen is obtained, if it lies below
the limit, the weight of sand mixture will be increased and a new specimen will be prepared).
The specimen conforming to within limits represent the standard specimen required.
The standard specimen was prepared by having a diameter of 50mm and height 50mm as shown
in Plate 3.8. The standard specimen was placed 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).
The valve of the permeability meter as shown in Plate 3.9 was operated and the stop watch was
started simultaneously. When the zero mark on the inverted jar just touches the top of water tank,
the manometer reading will be noted down. The time required to pass 2000 cm3
of air through the
specimen was noted. The permeability number (Pn) was calculated by using the formula below.
=
∗
∗ ∗
(3.4)
Where
V = Volume of air passing through the specimen, 2000 cm3
H = Height of the specimen = 5.0 cm (standard value)
P = Pressure as read from the manometer in gm/cm2

55
Plate 3.7: Ridsdale-Dietert metric standard rammer

56
Plate 3.8: 50 mm x 50 mm height sample stripped from sample-holder

57
Plate 3.9: Ridsdale-Dietert Permeability meter

58
A = Area of the specimen = d2
/4
Where d = 5.0cm (standard value)
T= Time in minutes for 2000cm3
of air passed through the sand specimen.
ii. Determination of green compressive strength of the mould sand
The materials used for this test were; base sand (500g), clay (10%) and water (5%).The
apparatus used to carry out this experiment were; 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.
A weighed proportion of sand and clay was taken and was dry mix together in a Muller for 3
minutes; an appropriate percentage of water was then added. The sand mixture was transferred
into the tube and rammed with the help of a sand rammer thrice to produce the standard
specimen. The standard specimen was removed by the stripper and then placed between shackles
which are fixed in the sand testing machine as shown in Plate 3.10. The handle of the testing
machine was rotated to actuate the ram. Thus hydraulic pressure was applied continuously till the
specimen raptures. The green compression strength was read from the gauge and recorded.
iii. Determination of green shear strength on the mould sand
The materials required for the test are; base sand, clay and water. The required apparatus needed
for this experiment are; Sand ramming machine (rammer), universal sand testing machine with
attachments, weighing pan.
Weighed amount of foundry sand (mixture of sand, clay & water as specified) was taken. The
sand mixture was transferred into the tube and was rammed with the help of a sand rammer
thrice. The shackles were fixed to the universal sand testing machine. The specimen was
removed from the tube with the help of a stripper and was loaded into the universal sand testing

59
Plate 3.10: Ridsdale-Dietert universal sand strength machine

60
machine. The hydraulic pressure was applied by rotating the handle of the universal sand testing
machine continuously until the specimen ruptures. The shear strength was read directly from the
scale.
3.3.3 Determination of elemental composition in the sands
Metals in the samples (base sands) were analyzed using Atomic Absorption Spectrophotometry
(AAS).
3.3.3.1 Digestion of soil samples
1 g of the dried, grinded soil sample was weighed accurately into a clean Teflon beaker, 20 mL
HF (Hydrogen Fluoride) was added and heated to near dryness, 15 mL of HNO3 (Nitric acid) was
then added and heating resumed to mop up the residue, again on near dryness, it was allowed to
cool, 20 mL distilled water was added to boil off the acid. After boiling to one-third its volume,
the sample was allowed to cool and filtered. The filtrate was made up to mark in a std flask with
distilled water.
3.3.3.2 Analysis
The samples were analysed with PG990 AAS for the elemental composition in the samples by
flame atomization, using air-acetylene flame and single element hollow cathode lamp and
following the equipment procedures.
3.4 Design of Experiment
The process parameters to be considered for this project work are; grain fineness number (GFN),
moisture content, shakeout-time and pouring temperature. To identify most influencing process
parameters among the selected parameters for grey cast-iron sand castings and optimize them to
improve the quality of the castings and enhance the mechanical properties of the casted product,

61
Taguchi’s robust methodology of design of experiment will be applied. The methodology of
Taguchi’s robust methodology (Mohammed et al, 2016) is itemized below. Table 3 shows the
control factors and their levels. Table 4 shows Standard Orthogonal Array - L9 (34
), and Table 5
shows the experimental design used for this research work considering of four factors at three
different levels.
3.5 Design of Gating and Feeding System
According to Ahmed (2015), a proper gating system is designed;
i. To fill the mould cavity without breaking the flow of liquid metal and without using very high
pouring temperatures.
ii. To avoid erosion of mould cavity.
iii. To minimize turbulence and dross formation.
iv. To prevent aspiration of air or mould gases in the liquid metal stream.
v. To obtain favourable temperature gradients to promote directional solidification.
3.5.1 Design of riser (feeder)
The primary function of a riser is to act as a reservoir of molten metal in the mould to
compensate for shrinkage during solidification (Karunakar, 2009). The secondary functions of a
riser are;
i. It gives an indication that the cavity is full with the molten metal.
ii. It also enables escape of hot gases during pouring of molten metal
3.5.1.1 Guidelines for riser design and location
i. The riser (feeder) must not solidify before the casting
ii. The volume of risers must be large enough to feed the entire shrinkage of the casting

62
Table 3: Control Factors and their Levels
FACTOR CODE
LEVEL
1 2 3
Grain fineness number A 63.3 68.27 67
Moisture content (%) B 5 6 7
Shakeout time (min) C 40 45 50
Pouring temperature (o
C) D 1300 1350 1400

63
Table 4: Standard Orthogonal Array- L9 (34
)(Mohammed et al, 2016)
Experimental Number A B C D
1 1 1 1 1
2 1 2 2 2
3 1 3 3 3
4 2 1 2 3
5 2 2 3 1
6 2 3 1 2
7 3 1 3 2
8 3 2 1 3
9 3 3 2 1

64
Table 5: Experimental Design
Experiment
No
Grain Fineness
Number (GFN)
Moisture Content
(%)
Shakeout Time
(min.)
Pouring
Temperature (o
C)
A B C D
1 63.3 5 40 1300
2 63.3 6 45 1350
3 63.3 7 50 1400
4 68.27 5 45 1400
5 68.27 6 50 1300
6 68.27 7 40 1350
7 67 5 50 1350
8 67 6 40 1400
9 67 7 45 1300

65
iii. The pressure head from the riser should enable complete cavity filling
iv. Riser must be placed so that it enables directional solidification.
3.5.1.2 Riser calculation
Using the Naval Research Laboratory (NRL) method (Karunakar, 2009);
For regular shape, Sf = (3.5)
Where;
Sf = Shape factor; L= Length; W = Width and T = Thickness
Assuming L = W = D for a circular section
Where;
D = Average diameter of the pulley = 160 mm
T = Average Thickness of the pulley = 25 mm
Sf = (3.6)
Sf =
∗
= 13
From NRL graph
VR/VC= 0.38
Where;
VR= Volume of riser
VC= Volume of casting

66
= ∑ *D2
*T (3.7)
Where,
D is diameter of casting
L is thickness of casting
=
∗ ∗ ∗
+
∗ ∗ ∗
= 540353.94 mm3
= 540360 mm3
(545 cm3
) approximately
VR= VC* 0.38= 545 cm3
* 0.38 = 207 cm3
(207000 mm3
)
From NRL Riser selection chart
Riser height, H = 3 cm (30 mm) from corresponding value of VR
Since H/D = 0.5
Then, D = H/0.5 = .
= 60 mm (6 cm)
Where, D is the diameter of riser
3.5.2 Design of pouring basin
According to Rashid (2009), the pouring basin to be used is to be decided based on the size of
the product to be casted.
i. Conical pouring cup (can be used for small casting)
a. Hand ladle filling (50 mm above the entrance to the sprue) monograms can be used.
b. Poured directly from furnace (usually from a height) monogram cannot be used.
ii. Pouring bush/basin (for larger casting).

67
3.5.2 Design of down-runner or sprue
In designing a proper sprue (Rashid, 2009), the necessary procedure to follow are;
i. Calculate the weight of liquid metal to be poured (includes the casting, the feeder, and
all elements of gating system)
Density of solid grey cast iron = 7.86 g/cm3
Density of liquid grey cast iron = 6.9 g/cm3
Fluidity length = 22 inches
Height of cope = 50 mm
Volume of casting, VC = 545 cm3
W= ρ × V (3.8)
Where;
W = Weight; ρ = density and V = volume
= 7.86 g/cm3
* 545 cm3
= 4283.7 g ≈ 4.28 kg
Assuming casting yields 70%
Wm = (3.9)
Where;
Wm = Weight of poured metal,
mc = Mass of casting and
Yc = casting yield

68
W =
.
.
≈ 6 kg
ii. Choose location and design of gating system.
iii. Determine/decide on total filling time of casting.
The pouring time for grey iron casting can be calculated as follows:
(a) Gray iron castings less than 450 kg
t = ∗ (1.41 +
.
) *√ seconds (3.10)
Where;
k = fluidity factor
k = (3.11)
F = Fluidity of iron, inches
δ = average thickness of casting, mm
W = weight of metal poured, kg
t = pouring time
t = ∗ (1.41 + .
) √ seconds (3.12)
= ∗ (1.41 +
.
) √6
≈ 4.2 s
To calculate the optimum pouring rate for ferrous metals and copper-base alloy castings the
following equation can be applied:
R= (WP
/ (1.34+ .
)) kg/s (3.13)
Where;

69
W = weight of casting, kg, t = critical casting thickness, mm, and P = constant (depends upon
the weight of casting).
The value of constant P for different castings is as shown in Table 6:
Table 6: The Value of Constant P with Corresponding mass (Rashid, 2009)
Casting mass, kg up to 500 500-5000 5000-15000
Constant, P 0.50 0.67 0.70
iv. Find average filling rate in the gating system
Average filling rate, Kg/s = Weight of casting/ filling time
v. Select the velocity of flow
For Cu-base and Fe-base alloys, velocity of flow = 500 mm/s
vi. Calculate the choke area
Ac = W / [ρ*t*C* (2*g*Hc)0.5
] (3.14)
Ac = choke area,
W = casting weight (total, including all elements) = 6 kg,
ρ = density of molten metal = 6.9 g/cm3
= 6.9*10-6
kg/mm3
,
Hc = Height of cope = 50 mm,
C = discharge coefficient (= 0.8),
g = acceleration due to gravity (=9.81 m/s2
or 9810 mm/s2
),
t = pouring time = 4.2 seconds.
Ac =
. ∗ . ∗ ∗ . ∗ √ ∗ ∗

70
= 261.29 mm2
≈ 262 mm2
Choke diameter, Dc ≈ 18.5 mm
vii. Calculate the sprue top area.
Using Law of Continuity,
Q = A1V1 = AcV2 (3.15)
Using Bernoulli’s Theorem, V2
= 2gH and then using law of continuity to obtain the equation
A1= Ac√ (Hc/h1) (3.16)
A1 = sprue top area, Ac = Choke area, h1 = distance between ladle and sprue top, and h2=distance
between ladle and sprue bottom.
viii. Calculate the area of sprue well
The sprue well is used to trap and catch the first metal and to absorb erosion of the sand due to
kinetic energy of molten metal. The sprue well area is usually two to three times the sprue exit
(choke area)
Sprue well area = 2 * Ac
= 2 * 262 =524 mm2
Sprue well diameter ≈ 26 mm
ix. Selection of the appropriate gating ratio for the casting
Un-pressurized system will be considered in order to reduce metal velocity and turbulence. Un-
pressurized system for grey cast iron is often designed to follow ratio of 1:4:4 with respect to;
Sprue exit (Ac): Total runner (AR): Total gate (AG); that is, gating system is un-pressurized if
area is increasing (e.g. 1:4:4).
x. Design of runner
AR= 4Ac (3.17)

71
= 4 * 262 = 1048 mm2
Height of runner = Width of runner = a
a2
= 1048
a≈ 32.5 mm
xi. Design of in-gates
Number of in-gates taken = 2
Cross sectional area of each in-gate = = 524 mm2
Let the height of each in-gate = a
Width of each in-gate = 2a
2a2
= 524
a≈ 16.2
Height of each in-gate = 16.2 mm
Width of each in-gates = 32.4 mm
3.6 Design of Cast Iron Pulley
The following procedure will be adopted for the design of cast iron pulleys (Khurmi and Gupta,
2005).
i. Dimensions of pulley
(a) The diameter of the pulley (D) may be obtained either from velocity ratio consideration or
centrifugal stress consideration. It is known that the centrifugal stress induced in the rim of the
pulley is given as;
σt = ρ * ν2
(3.18)
Where;
ρ = Density of the rim material= 7200 kg/m3
for cast iron

72
ν = Velocity of the rim = , D being the diameter of pulley and
N is speed of the pulley.
The following are the diameter (Khurmi and Gupta, 2005) of pulleys in mm for flat and V-belts.
20, 22, 25, 28, 32, 36, 40, 45, 50, 56, 63, 71, 80, 90, 100, 112, 125, 140, 160, 180, 200, 224,250,
280, 315, 355, 400, 450, 500, 560, 630, 710, 800, 900, 1000, 1120, 1250, 1400, 1600, 1800,2000,
2240, 2500, 2800, 3150, 3550, 4000, 5000, 5400.
The first six sizes (20 to 36 mm) are used for V-belts only.
(b) If the width of the belt is known, then width of the pulley or face of the pulley (B) is
taken25% greater than the width of belt.
∴B = 1.25*b; where b = Width of belt.
According to Indian Standards, IS: 2122 (Part I) – 1973 (Reaffirmed 1990), the width of pulleyis
fixed as given in the Table 7:
The following are the width of flat cast iron and mild steel pulleys in mm:
16, 20, 25, 32, 40, 50, 63, 71, 80, 90, 100, 112, 125, 140, 160, 180, 200, 224, 250, 315, 355, 400,
450, 560, 630.
(d) The thickness of the pulley rim (t) varies from300D+ 2 mm to200D+ 3 mm for single
belt and 200D+ 6 mm for double belt. The diameter of the pulley (D) is in mm.
3.7 Production of the Cast Product
The production of cast product in sand casting process require; the production of pattern with
allowable machining allowance, preparation of the mould sand, melting of scrap grey cast-iron
and pouring of molten metal through the sprue to the mould cavity, and shaking out of the cast
product.

73
3.7.1 Production of pattern
The pulley’s pattern was turned on a wood lathe into the dimension of diameter 160mm by
25mm thickness with a parasitic dimension of diameter 40mm by 30mm thickness. The pattern is
shown in plate 3.12.
3.7.2 Preparation of moulding sand
The various silica sands were sieved with a sieve aperture of 180 . The silica sands were
mulled together with the appropriate percentage of moisture (or water), the pattern was placed in
the drag and backing powder was applied to the pattern for easy removal and a good formation
of surface finish cavity, the moist sand was poured in the drag and rammed simultaneously. The
drag was turned other way round in order to place the cope on it, the cope was placed on the drag
and also filled with the moist sand and rammed simultaneously in which the runner, sprue, riser
and in-gates were formed at the appropriate locations on the mould. The pattern was removed for
after the flask was completed. Plate 3.11(a), 3.11(b) and 3.12 shows the pattern, when the pattern
was rammed in the drag and the complete moulds respectively.
3.7.3 Melting and pouring of molten metal
The grey cast iron scraps were melted in the furnace with the help of a crucible pot (as shown in
Plate 3.13), the molten metal was poured to the nine different moulds at three different
temperature; 1300°C, 1350°C and 1400°C.
3.7.4 Shakeout of cast product
The cast products were shakeout 40, 45 and 50minutes after the molten metal had been poured
into the moulds depending on the shakeout time of the experiments. Plate 3.14 shows the cast
products after shakeout.

74
Plate 3.11(a): pattern
Plate 3.11(b): Pattern in the drag

76
Plate 3.13: Molten metal in crucible pot

77
Plate 3.14: Cast product (Pulley)

78
3.8 Mechanical Properties Examination
Test pieces were cut from the different results obtained from the design of experiment. These test
pieces was then subjected to hardness and impact tests to determine the best casting output.
3.9 Signal-to-Noise Ratio
Signal-to-noise (S/N) ratio is the most important component of the factor design. Signal-to-noise
ratio as an evaluation tool was used to determine the robustness of the design, In the Taguchi
method, the term ‘signal’ represents the desirable target and ‘noise’ represents the undesirable
value. The S/N for each factor level was calculated using the following formula.
S/N = -10log10 ( ∑ ) (3.19)

79
Table 7: Standard Width of Pulley (Khurmi and Gupta, 2005)
Belt Width
(mm)
Width of pulley to be greater than belt width by
(mm)
up to 125 13
125-250 25
250-375 38
475-500 50

80
Figure 8: Gating system and pulley model

81
Figure 9: Exploded View of Gating System

82
CHAPTER FOUR
RESULT AND DISCUSSION
4.1 Moisture and Clay Content of the Sands
The moisture and clay contents of the various sand of consideration are analysed in Table 8 and
Table 9 respectively. The percentage moisture contents for Opa river sand, Isheri-Oke river sand
and Osogbo river sand are 16%, 13.8% and 10.4% respectively. The variations of moisture
content present in the sand rivers are shown in Figure 10 with aid of a chart.
The percentage clay content for Opa, Isheri-Oke and Osogbo river sands are 4.7%, 5.4% and
5.2% respectively. The variations of clay content present in the sand rivers are shown in Figure
11 with aid of a chart.
4.2 Sieve Analysis and Determination of Grain Fineness Number of the Sands
The result showed that Grain Fineness Number (GFN) were 63.3 and 68.27 for Opa and Isheri-
Oke sands respectively. The GFN for Osogbo river is 67 (Ejairu and Falade, 2017). These values
are in accordance with the grain fineness number used by most foundries, which is expected to
be between 40 and 220 (Oke and Omidiji, 2016). Table 10 and Table 11 present the sieve
analysis of the various sands. The graph of percentage retained against sieve aperture (microns)
is shown in Figure 12 and 13 below.
4.3 Determination of Permeability Number and Green Compressive Strength
The permeability test and the green compressive strength were carried out at Federal Institute of
Industrial Research, Oshodi (FIIRO), in Lagos State with the mixing composition of; 500g of
sand, 10% bentonite and 5% water. The results for the permeability number and green strength
are 82.4, 27 kN/m2
and 124.73, 15 kN/m2
for Opa and Isheri-Oke respectively.

83
Table 8: Moisture Content Result for Opa, Isheri-Oke and Osogbo River Sands
S/No Sand Locations
Initial Weight of
moist sand (w1)
Weight of dried
sand (w2)
Moisture content
(w1 –w2)
% Moisture in
sand
1 Opa 50g 42g 8g 16%
2 Isheri-Oke 50g 43.1g 6.9g 13.80%
3 Osogbo 50g 44.8 5.2g 10.40%
Table 9: Clay Content Result for Opa, Isheri-Oke and Osogbo River Sands
S/No
Sand
Locations
Weight of sand
with clay(w1)
Weight of dried sand
without clay (w2)
Clay content
(w1 –w2) % Clay in sand
1 Opa 100g 95.3g 4.7g 4.7%
2 Isheri-Oke 100g 94.6g 5.4g 5.4%
3 Osogbo 100g 94.8g 5.2g 5.2%

84
Figure 10: Percentage moisture content against sand location
Figure 11: Percentage clay content against sand location
4.20%
4.40%
4.60%
4.80%
5.00%
5.20%
5.40%
5.60%
Opa Isheri-Oke Osun-Oshogbo
Percentage(%)Moisturecontents
Sand Locations
% Clay contents
4.20%
4.40%
4.60%
4.80%
5.00%
5.20%
5.40%
5.60%
Opa Isheri-Oke Osun-Oshogbo
percentage(%)Claycontents
Sand location
% Clay contents

85
Table 10: Sieve Analysis for Determination of GFN (Opa river sand)
S. No
Sieve Aperture
(microns)
Weight retained
(g)
% Weight
retained Multiplier Product
1 1000 3.8 7.6 5 38
2 850 2.0 4 10 40
3 710 0.2 0.4 20 8
4 500 5.2 10.4 30 312
5 425 2.0 4 40 160
6 355 6.0 12 50 600
7 212 23.0 46 70 3220
8 180 1.2 2.4 100 240
9 150 2.6 5.2 140 728
10 70 1.4 2.8 200 560
11 pan 0.2 0.4 300 120
Total 47.6 95.2 6026
Grain Fineness Number (GFN) = .
≈ 63.3

86
Table 11: Sieve Analysis for Determination of GFN (Isheri-Oke river sand)
S. No
Sieve Aperture
(microns)
Weight retained
(g)
% Weight
retained Multiplier Product
1 1000 3.8 7.6 5 38
2 850 2.4 4.8 10 48
3 710 0.1 0.2 20 4
4 500 7.0 14 30 420
5 425 2.4 4.8 40 192
6 355 6.4 12.8 50 640
7 212 20.1 40.2 70 2814
8 180 1.6 3.2 100 320
9 150 2.2 4.4 140 616
10 70 2.4 4.8 200 960
11 pan 1.2 2.4 300 720
Total 49.6 99.2 6772
Grain Fineness Number (GFN) =
.
≈ 68.27

87
Figure 12: Percentage retained against sieve size for Opa sand
Figure 13: Percentage retained against sieve size for Isheri-Oke sand
0
5
10
15
20
25
30
35
40
45
50
1000 850 710 500 425 355 212 180 150 70
%Retained
Sieve Aperture (microns)
Series1
0
5
10
15
20
25
30
35
40
45
1000 850 710 500 425 355 212 180 150 70
%Retaied
Sieve Aperture (microns)
Series1

88
The sample used for permeability and the green strength was the one obtained through the 1400
microns sieve aperture. According to Ayoola et al., (2010), the permeability and green
compressive strength for Osogbo sand is 79 and 15.5 kN/m2
respectively with the mixing
composition of; 81.89% sand, 4.56% water, 4.5% bentonite and 9.06% coal-dust.
4.4 Determination of Green Shear Strength of the Sand Samples
The green shear strength of the sand samples were carried out at Elizade University, Ilara-mokin
and the results obtained for Opa and Isheri-Oke river sands are 17.86kN/m2
and 22.32 kN/m2
respectively. The green strength for Osogbo sand (Ayoola et al., 2010) was determined to be
21.5 kN/m2
.
4.5 Determination of Elemental Composition in the Mould Sands
Atomic Absorption Spectophotometry (AAS) method was used to determine the elemental
composition of the sand samples used. The metal concentrations present in the samples were
conducted at Centre for Energy and Research Development (CERD) in OAU, Ile-Ife. The results
of the total metal concentrations present in the samples are shown in Table 12 and Table 13. The
metal concentrations in the Osogbo sand are shown in Table 14 and Table 15. Figure 14 below
shows the correlation within the percentage metal concentration in Opa, Isheri-Oke and Oshogbo
sands.
4.6 Determination of Mechanical Properties of the Casting
The casting was carried out using Taguchi’s L9 standard orthogonal array method by varying
four process parameters at three different levels. The hardness test was carried out on the various
nine samples at The Polytechnic, Ibadan using Rockwell Hardness Testing machine (shown in
Plate 3.15). The result shown in the Table 16 is the average value read from the scale B on the

89
Rockwell hardness testing machine. The impact test was carried out on the nine impact testing
pieces with diameter 8mm, appreciable length and a 45o
notch at the center with a depth of 1mm
shown in Plate 3.16 at the department of Material Science and Engineering, OAU, using the
Balance Impact Testing Machine (shown in Plate 3.17). Table 16 shows the results obtained for
the various nine samples alongside with the various results obtained for the hardness.

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