EFFECT OF MELTING TEMPERATURE ON DIMENSIONAL ACCURACY IN

SAND CASTING PRODUCT

AHMAD FAIZAL BIN MOHAMAD

Thesis submitted in partial fulfillment of the requirements

for the award of the degree of

Bachelor of Mechanical Engineering

Faculty of Mechanical Engineering

UNIVERSITI MALAYSIA PAHANG

NOVEMBER 2009

ii

SUPERVISOR’S AND CO-SUPERVISOR’S DECLARATION

I hereby declare that I have checked this project and in my opinion, this project is adequate

in term of scope and quality for the award of the degree of Bachelor of Mechanical

Engineering.

Signature

Name of supervisor: NUR AZHANI BT ABD. RAZAK

Position: LECTURER

Date:

Signature

Name of co-supervisor: MUHAMMED NAFIS BIN OSMAN ZAHID

Position: LECTURER

Date:

iii

STUDENT’S DECLARATION

I hereby declare that the work in this project is my own except for quotations and

summaries which have been acknowledged. The project has not been accepted for any

degree and is not concurrently submitted for award of other degree.

Signature

Name: AHMAD FAIZAL BIN MOHAMAD

ID Number: MA06061

Date:

iv

Especially dedicated to my parents, brother and sister

My love to all of you will remain forever…

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ACKNOWLEDGEMENT

First of all I am grateful to ALLAH S.W.T for blessing me in finishing my final

year project (PSM) with success in achieving my objectives to complete this project.

. I would like to convey my deepest appreciation to my supervisor Ms. Nur Azhani

binti Abd. Razak and my co-supervisor Mr. Muhammed Nafis bin Osman Zahid for

guiding and supervising my final year project throughout these two semesters. They have

been very helpful to me in finishing my project and I appreciate every advice that they gave

to me in correcting my mistake. I beg for the forgiveness to my supervisor and co-

supervisor for any mistakes and things that I have done wrong while doing my project.

Special thank to, Ir. Mohd Rashidi Maarof and Mr. Asnul Hadi Ahmad (Foundry

Lab) for their help and kindness in doing me a favor in getting additional information for

the project. Also, I would like to thank my panel, Mr. Hadi Abdul Salaam, Mr. Ramli

Junid and Ms. Norhaida Ab. Razak for his invaluable guidance and advices to improve my

thesis. Also thanks to my friends especially A. Bakhtiar, M. Shariman, T.A. Firdaus, M.

Fakhri, M. Saiful and M.K Izzat. I appreciate all your support and advice.

I would like to express my deepest appreciation and gratitude to my family

members for their love, sacrifice, motivation and support given during the course of the

project. I also indebted to the many individual who have provided information and insight

that might help to complete this thesis and also throughout my study in UMP as they are

my inspiration to success.

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ABSTRACT

This study is conducted based on the needs to find accurate method for sand casting in

producing the clamping vise. Vise is well known as for clamping the work piece. This

study is carried out to investigate effect of temperature on dimensional accuracy (mm) of

the finish product using sand casting and to find the optimum melting temperature of

aluminum for sand casting process. Different setting of melting temperature is applied for

sand casting process which is 660°C, 720°C and 780°C. These temperatures are taken using

infra red (IR) thermometer. Final products are measured using vernier caliper with

tolerance (±0.03 mm) respectively. The data obtained are analyzed using standard analysis

method and graph is plotted for graphical analysis purpose. The result showed that melting

temperature 720°C has better dimensional accuracy rather than melting temperature 660°C

and 720°C. From the analysis, it showed that every different setting of melting temperature

influenced the performance of final parts in terms of dimensional accuracy (mm).

vii

ABSTRAK

Kajian ini dijalankan berpandukan kepada keperluan dalam mencari cara yang paling tepat

dalam menghasilkan ragum menggunakan proses tuangan pasir. Ragum lebih dikenali

untuk maragum alatan kerja. Kajian ini dijalankan untuk menyiasat kesan suhu ke atas

ketepatan dimensi (mm) produk akhir menggunakan sand casting dan mencari suhu cair

paling optimum bagi aluminium bagi tuangan pasir. Tiga peringkat suhu cair di tetapkan

untuk proses tuangan pasir di mana suhu tersebut ialah 660°C, 720°C dan 780°C. Suhu-

suhu ini diukur menggunakan thermometer infra merah (IR). Dimensi produk akhir diukur

menggunakan angkup vernier dengan toleran sebanyak (±0.03 mm). Data tersebut

kemudian dianalisis menggunakan analisis standard dan untuk analisis grafik, graf

diplotkan. Keputusan menunjukkan suhu cair 720°C mendapat ketepatan dimensi paling

baik berbanding suhu cair 660°C and 720°C. Daripada analisis juga menunjukkan suhu cair

yang berlainan akan mempengaruhi prestasi produk akhir dalam kontek ketepatan dimensi

(mm).

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TABLE OF CONTENTS

PAGE

SUPERVISOR’S AND CO-SUPERVISOR’S DECLARATION ii

STUDENT’S DECLARATION iii

ACKNOWLEDGEMENTS iv

DEDICATION v

ABSTRACT vi

ABSTRAK vii

TABLE OF CONTENTS viii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF SYMBOLS xiv

LIST OF ABBREVIATION xv

CHAPTER 1 INTRODUCTION

1.1 Preface 1

1.2 Background of The Study 2

1.3 Problem Statement 3

1.4 Objective of The Study 3

1.5 Importance of The Study 3

1.6 Scope of The Study 3

1.7 Rationale of The Study 4

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction 5

2.2 Vice 5

2.3 Rapid Tooling

2.3.1 Indirect Tooling

6

7

ix

2.4 Sand Casting 7

2.4.1 Sand Molds 9

2.4.2 Pattern 11

2.4.3 Sand Casting Alloys 11

2.4.4 Sand Preparation 12

2.4.5 Gating System 13

2.5 Engineering Metrology and Instrumentation 14

2.5.1 Measuring and Instruments 15

CHAPTER 3 METHODOLOGY

3.1 Introduction 16

3.2 Experimental Design 16

3.2.1 Parameter of Study 17

3.2.2 Number of Trials 17

3.3 Study Output 18

3.3.1 Dimensional Accuracy (mm) 18

3.3.2 Melting Temperature 21

3.4 Data Analysis 21

3.4.1 Variation and Error Values 21

3.4.2 Graphical Analysis

22

3.5 Procedure of The Study 23

3.6 Materials 25

3.6.1 Polystyrene 25

3.6.2 Aluminum 26

3.7 Instrumentation 27

3.7.1 Design Tools 27

3.7.2 Sand Casting 28

3.7.3 Measuring Instrument 32

CHAPTER 4 RESULT AND DISCUSSION

4.1 Introduction 35

4.2 Dimensional Accuracy (mm) 35

x

4.2.1 Master Pattern 35

4.2.2 Casting Process Part 36

4.3 Dimensional Accuracy Analysis 38

4.4 Discussion in Dimensional Accuracy for Different Melting Temperature 43

4.4.1 Dimensional Accuracy (mm) 44

4.5 Errors Due to Experiment 46

CHAPTER 5 CONCLUSIONS AND RECOMENDATIONS

5.1 Introduction 51

5.2 Summary 51

5.3 Conclusion 52

5.4 Recommendations for Future Study 52

REFERENCES 53

APPENDICES

A Gantt Chart for FYP 1 55

B Gantt Chart for FYP 2 56

C Exhibits of Projects 57

D Mitutoyo Vernier Caliper Catalogue 61

xi

LIST OF TABLES

Table No. Title Page

2.1 Commonly Used Sand Casting Alloys 12

3.1 Parameters of Study 17

3.2 Selected Temperature of Aluminium for Sand Casting 21

3.3 Mechanical Properties of Polystyrene 26

3.4 Mechanical Properties of Aluminum 27

4.1 Dimension Measurement of the Master Pattern 36

4.2 Dimension of Casting Part Due to Different Melting

Temperature

37

4.3 Normal Shrinkage Allowance for Metals 50

xii

LIST OF FIGURES

Figure Title Page

2.1 Schematic Diagram for Vice 6

2.2 Assembled Cope and Drag Mould 9

2.3 Typical Gating System 14

3.1 Process Flow from Master Patterns to Final Parts 18

3.2 The Design Of Vice 19

3.3 Front View Of Vice 20

3.4 Top View Of Vice 20

3.5 Example of Plotted Graph for Dimensional Accuracy 23

3.6 The Experimental Flow Process 24

3.7 Example of Sand Casting Mould 29

3.8 The pattern first makes an impression in the cope and drag 30

3.9 The cope and drag are then combined and are ready to

accept the metal

31

3.10 The metal is heated and prepared metallurgically. It is

transferred to a crucible just before pouring

31

3.11 The molten metal is then poured into the mold 31

3.12 The part is allowed to sit and cool. Once cooled the

casting and gating system are removed from the mold and

the sand is recycled

32

3.13 The casting is then sent to the finishing department where

any remains of the gates are ground off

32

3.14 The part is cleaned 32

3.15 Parts of the vernier callipers 33

xiii

4.1 Seven Critical Points to Measure the Dimensional

Accuracy

36

4.2 Differences in Dimensional Accuracy for Melting

Temperature 660°C

38

4.3 Differences in Dimensional Accuracy for Melting

Temperature 720°C

39

4.4 Differences in Dimensional Accuracy for Melting

Temperature 780°C

40

4.5 Differences in Dimensional Accuracy for All Melting

Temperature

41

4.6 Difference in Variation of Different Melting Temperature 42

4.7 Percentage of Error for All Melting Temperature 43

4.8 Basic Phase Diagram for Aluminum 45

4.9 Dimensional Tolerances as a Function of Part Size for

Various Manufacturing Process

47

4.10 The Casting Part Not Solidify Completely 48

xiv

LIST OF SYMBOLS

% Percentage

ºC Degree celcius

P Pressure

T Temperature

xv

LIST OF ABBREVIATION

CAD Computer Aided Design

IR Infra red

RT Rapid Tooling

CHAPTER 1

INTRODUCTION

1.1 PREFACE

In this study, vise is produced by using sand casting process. The important

element in this study is how to build the accurate vise using sand casting process and

also need to consider the effect of different temperature. Sand casting process is done in

Foundry Laboratory at Universiti Malaysia Pahang (UMP).

The conceptual model of part is created by using one of the CAD (Computer

Aided Design) software called SolidWorks. Typically, these processes involve the

design of the vise part using SolidWorks because easy for the designer to interpreted

their design and not only fitted with 2Dimensional axis only. Using SolidWorks, the

design can be drawn in 3-Dimensional (3D) and also drawn in full scale measurement.

The master pattern from SolidWorks is then transferred to actual master pattern

to create a final part. The actual master pattern is made up from polystyrene and

polystyrene is been cut using polystyrene cutter. The reason using polystyrene cutter is

because polystyrene has low melting point about 240°C and easy to shape the actual

design if a little heat is applied to the polystyrene. Polystyrene cutter is a useful tool to

produce an actual product in a shorter period of time.

Next process is sand casting process and is done by melt the actual master

pattern in Carbon Dioxide (���) sand mold. The quality characteristic such as

dimensional accuracy will be analyzed using vernier caliper respectively.

2

Apart from that, the reason to conduct this study is to compare the dimension

between existing actual master pattern with the one produced by sand casting. Several

literature reviews, generally from published journal, are undertaken into this study to

identify the significant effect of dimensional accuracy of produced parts. Hence, hoped

this study will be a useful guideline for future research and applications of rapid tooling

in other industries especially in automotive industry.

1.2 BACKGROUND OF THE PROBLEM

In this study, it consists of two major phase to come out with final product. The

first phase is design phase which is the master pattern is drawn using SolidWorks. Then

the master pattern is being made by using polystyrene. The polystyrene is cut using

polystyrene cutter. After that, the processes go to the second phase which is sand casting

process. In this process, there are a few major steps that are needed in sand casting. First

process is preparing the mould. After that, fill in the mould with ���gas that will make

the sand mould harden like concrete. Then the aluminum is heated until it melted and

after that the molten metal is poured into the mould until it fills in all in the mould.

After got the product, the dimension of the final product is measured using vernier

caliper. Then the dimension of final product is compared between the master patterns

from polystyrene. All the data is documented in the table.

1.3 PROBLEM STATEMENT

This study is aimed to find out the answer for the following question which is

the dimension of sand casting produced part is not same as the master pattern.

Dimensional accuracy is very important when sand casting is applied because if the

final product not accurate, so the product will malfunction. For example, when

produced engine piston, the dimension is piston need to follow a certain tolerance. If the

piston did not follow the tolerance, the piston wills not malfunction. The manufacturer

needs to redo back the casting process and it will cost more for making the product.

3

1.4 OBJECTIVE OF THE STUDY

The main objective of this study is to investigate the effect of temperature on

dimensional accuracy of the finish product using sand casting. Second objective is to

find the optimum melting temperature of aluminum for sand casting process.

1.5 IMPORTANCE OF THE STUDY

Within the study of this project, many benefits can be obtained and concluded as

outlined below:

(i) To help the manufacturer in automotive field or manufacturing field in

order to reduce the cost to produce the final product using sand casting

process.

(ii) This study also helps to investigate the capability of aluminum material

as a master pattern.

(iii) Generally, using sand casting process offers the most economical

production cost and results from this study will attract more interest

using this method in producing the vise and also aluminum can be

renewable if the produced part is not fulfill the specification of the study.

1.6 SCOPE OF THE STUDY

Below are included scopes:

(i) Effect of casting temperature with product dimensional accuracy.

(ii) Find the optimum temperature for molten metal to achieve high

dimensional accuracy of part produce.

4

1.7 RATIONALE OF THE STUDY

The rationale of this study is to help the patternmaker and students in producing

the next clamping vise with better dimensional accuracy (mm). It also helps to minimize

the cost and time required as the drawing and data from this study will be recorded for

their future reference. Therefore, the database recorded plays an important role in

guiding them to produce the new clamping vise by using either the aluminum or other

materials which are suitable in sand casting application. Nevertheless, it is hoped that

this study will be a start for the next final year student to study and focus on the material

aspect.

CHAPTER 2

LITERATURE REVIEW

2.1 INTRODUCTION

This chapter will discuss about the usage of vise. Casting process is suitable

method to produce this product. Section 2.2 reviews on vice which states the uses of

product while rapid tooling (RT) is reviewed in Section 2.3. There is a review in sand

casting and basic theory of sand casting in Section 2.4. Meanwhile in Section 2.5, there

are explanation of engineering metrology and instrumentation.

2.2 VICE

A vice is a mechanical screw apparatus used for holding or clamping a work

piece to allow work to be performed on it with tools such as saws, planes, drills, mills,

screwdrivers, sandpaper, etc. Vices usually have one fixed jaw and another, parallel,

jaw which is moves towards or away from the fixed jaw by the screw. Vice usually

refers to a bench vice with flat, parallel jaws, attached to a workbench.

For metalworking, the jaws are made of metal which may be hardened steel with

a coarse gripping finish. Quick change removable soft jaws are being used more

frequently to accommodate fast change-over on setups. They are also keeping for use

and to protect the work from damage.

Metalworking bench vice, known as engineers or fitters vices, are bolted onto

the top surface of the bench with the face of the fixed jaws just forward of the front edge

of the bench. The bench height should be such that the top of the vice jaws is at or just

6

below the elbow height of the user when standing upright. The nut in which the screw

turns may be split. Means that the lever can be removed from the screw and the screw

and moveable jaw quickly slid into a suitable position at which point the nut is again

closed onto the screw. Many fitters prefer to use the greater precision available from a

plain screw vice. The vice may include other features such as a small anvil on the back

of its body. Figure 2.1 below shows the schematic diagram for vice.

Figure 2.1: Schematic diagram for vice

2.3 RAPID TOOLING

A much-anticipated application of rapid prototyping is rapid tooling, the

automatic fabrication of production quality machine tools. Jacobs et al. (2000) said that

tooling is one of the slowest and most expensive steps in the manufacturing process,

because of the extremely high quality required. Tools often have a complex geometry,

yet must be dimensionally accurate to within a hundredth of a millimeter (Ulrich K.T,

2000). Jacobs et al. (2000) also said that tools must be hard, wear-resistant, and have

very low surface roughness (about 0.5 micrometers root mean square). To meet these

requirements, moulds and dies are traditionally made by CNC-machining, electro-

discharge machining, or by hand. All are expensive and time consuming, so

7

manufacturers would like to incorporate rapid prototyping techniques to speed the

process. Rapid tooling can be divided into two categories, indirect and direct.

2.3.1 Indirect Tooling

Most rapid tooling today is indirect: Rapid prototyping (RP) parts are used as

patterns for making moulds and dies. RP models can be indirectly used in a number of

manufacturing processes (Chua, 1987).

In sand casting, a RP model is used as the positive pattern around which the sand

mold is built. Chua et al. (1987) said that a Laminated Object Manufacturing (LOM)

model, which resembles the wooden models traditionally used for this purpose are often

used. If sealed and finished, a LOM pattern can produce about 100 sand molds.

2.4 SAND CASTING

Sand casting is a process in which molten metal is poured into sand moulds,

which are broken away from the cast part after the metal, has solidified. Jacobs et al.

(2000) also said that sand casting consists of 6 major steps:

(i) Placing a pattern in sand to make an imprint.

(ii) Incorporating a gating system.

(iii) Filling the mold cavity with molten metal.

(iv) Allowing the metal to cool until it solidifies.

(v) Breaking away the sand mold.

(vi) Removing the casting part.

The sand moulds are made of two halves in which impressions are made by a

pattern. When the two halves are assembled, the impressions form a cavity into which

the molten metal is poured (F. Peter, 2007). The pattern resembles the part but is

slightly larger to accommodate for the metal shrinkage that occurs during cooling.

Patterns may contain multiple impressions, to form multicavity sand moulds, for the

economical production of large quantities of castings. A mixture of sand and a binding

8

agent is compacted around the pattern to form the two mould halves in separate metal

flasks.

Generally, the lower mould half is named the drag, and the upper mould half is

referred to as the cope. F. Peter et al. (2007) state that channels are formed in the drag to

feed the molten metal to the cavity or cavities in a multicavity mould. The opening of a

feed channel to its cavity is the gate, but often the complete set of feed channels is

referred to as the gating system. A pouring cup and vertical tapered channel in the cope

are used to deliver molten metal to the feed channels. Two additional features may

sometimes be required in a sand mould. First, one or more separate sand cores may be

placed in formed locations, called core prints, during assembly of the mould halves.

Second, an additional cavity, called a riser, may be formed in the cope to supply molten

metal pressure during solidification and shrinkage of the casting.

Sand cores are used in sand casting to produce internal cavities or undercuts (J.

Kron, (2007). Since the cores are broken out of the casting after solidification, complex

internal cavities are readily producible. The main requirement is that the internal

surfaces be accessible for the subsequent cleaning processes to remove adhering sand

particles. An assembled copes and drag mould, with both a sand core and a riser, is

shown in Figure 2.2. After metal solidification and cooling, the casting part in mold is

broken out of the sand the gating system is removed, and the cast part is cleaned of

adhering sand particles.

9

Figure 2.2: Assembled cope and drag mould

Sand castings can be made with extremely complex outer shapes. For

economical high-volume production the shape should contain a parting line around its

perimeter, each side of which has taper, called draft, for separation from the sand mould

(Raw, 2000). This is required not for separation of the finished casting from the mould,

but rather for removal of the pattern after the mould sand has been compacted around it.

Castings without draft may be produced by the use of multipiece patterns. In these cases

the pattern pieces can be disassembled for removal in different directions from the

compacted mould. This is a labor intensive and slow process used only for limited

production of very complex parts.

2.4.1 Sand Molds

Most sand casting operations use silica sand ������as mold material (Campbell,

2003). Sand is expensive and suitable as mold material. This is because of its high

temperature characteristics and high melting point. There are two general types of sand: