Improvement of Metal Casting
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IMPROVEMENT OF METAL CASTING TECHNIQUES IN THE SUDAN A THESIS SUBMETTED IN FULLILMENT OF THE REQUIREMENTS OF THE DEGREE OF Ph. D. IN MECHANICAL ENGINEERING UNIVERSITY OF KHARTOUM FACULTY OF ENGINEERING AND ARCHITECTURE DEPARTMENT OF MECHANICAL ENGINEERING BY ELJACK BABIKER ELJACK SUPERVISED BY Dr. ELAMIN ABDEL GALIL MAHMOUD Dr. KAMAL NASRELDIN ABD ALLA FACULTY OF ENGINEERING AND ARCHITECTURE UNIVERSITY OF KHARTOUM SEPTEMBER 2005 Dedication To the memory of my parents. To the memory of Dr. Eltahir Mohammed. Elbashier who was involved in the supervision of this work in the early stages. To my patient family, whose forbearance has been an incentive for me to work hard in this research. I hope this work shall contribute to the development of my beloved country the Sudan. I Acknowledgement I am greatly indebted to Dr. Elamin Abdel Galil Mahmoud and Dr. Kamal Nasr.Eldin Abd Alla for their unlimited support, helpful instructions and close supervision throughout the very lengthy process of this work. My gratitude to the Mechanical Engineering department and the Faculty of Engineering and Architecture, at the University of Khartoum for their great help and cooperation. My deep gratitude is extended to the managements of Yarmok Industrial Complex and Sea Shore Factory who provided me with references, materials and die-mould for the die-casting machine. I would like to thank the companies and individuals in the industry, who have helped me and provided information and advice: Izz-Eldeen Husain of Saudi Arabian air lines, Abu Bakr Mohamed El Hassan of Yarmouk Industrial Complex, and many other colleagues and friends without the support of whom, the completion of this work would have been much more difficult. Special thanks are due to Dr. Abdel Rahman Karar, for his great help in the electrical works. The thanks are further extended to Dean and the staff of the Graduate Collage at the University of Khartoum for their forbearance during the lengthy process of this work. Last but not least, I thank those many other organizations and individuals whose names have not been mentioned above, for every kind of support, help and cooperation in this work. II Abstract Metal casting enables the production of simple and complex parts that meet a wide variety of needs .Nearly all manufactured goods contain one or more cast components. Major end-uses include power generation equipment, defense systems and machinery, motor vehicles, transportation equipment, oil field machinery, pipelines, industrial machinery, construction materials, and other products vital to our economic and national security. The scope of the study is mainly made to cover the following areas:- I – Investigate the availability of materials in the Sudan for moulds construction for different metal casting processes as well as for producing parts by casting .The research showed that Sudan contains good quantities of scrap of various metal alloys beside natural resources of natural metals like iron and copper. II – Investigate the situation of metal casting Industry in the Sudan and the techniques adopted to the current activities .The survey work made on this area showed that the quality of the products is very poor because the industry of metal casting is lacking the following requirements:- i – Adoption of Scientific techniques . ii – Skilled labour . iii – Specialized engineers . iv – Proper equipment and tools . Due to the above reasons metal casting does not play any role in the plan of the development of Sudan. The adoption of the correct techniques will make the industry able to reduce its cost of production to become competitive with other manufacturing methods. Also energy content can be reduced by improving product quality-thereby reducing scrap and melting requirements. III – The research exerted great emphasis to put the foundry equipment of the Faculty of Engineering and Architecture (U of K) in good operational conditions to realize the three metal casting processes, sand casting, die casting and centrifugal casting can be performed. III اــــ اام ادن ا َّ آ ااء ذ ا وذات ا ا وا ء آ ات ا ها ال ان آ اا ت ا ا ى ء او اآ ا اء ا ا اآ ا آ ان ت اآ ا رة وا ات اج ا ‘ وات ا اع ‘ اآت ‘ و وات ا ‘ ‘ ات اول‘ ط ا ‘ اات ا ‘ اد اءات وت اى ال ادى وا ا . ها ا رآ اا ا -: -: ١. درا و اد ااد ا اا ا ا ادن و اا ا ا ااد ا ااء ً ن ادان زا دة ادن ،م ا و م اس . ٢. درا ه ا ادان وى ا ا ا ا ب اآ ه ا دورًا ا د ان . ا م را آت ادن ا ه ا آ ا . اه ارا أً آ و ات و آت آ ا وارة ام . و ا ذ وا هً ت ا اآ ا ،اآ ا ا اا اا وآ اآ ا ة اد اآ . IV Contents Dedication I Acknowledgement II English Abstract III Arabic Abstract IV List of figures XI List of Photo s XIII List of tables XIV Nomenclature XV CHAPTER ONE: INTRODUCTION 1 1.1 Historical background 2 1.2 Metal casting present situation in Sudan 2 1.3 Importance of metal casting 3 1.4 Overview of casting technology 4 1.5 Objectives of the research 6 CHAPTER TWO: LITERATURE REVIEW 16 2.1 Introduction to metal casting techniques 17 2.2. Expendable mould processes 17 2.2.1 Sand casting process 17 2.2.1.1 Green sand 18 2.2.1.2 Dry sand 18 2.2.1.3 CO 2 sand 18 2.2.1.4 Cold or chemically bonded sand 19 2.2.2 Shell moulding process 19 2.2.3 Vacuum moulding process 21 2.2.4 Expanded polystyrene process 22 2.2.5 Investment casting process 23 2.2.6 Plaster and ceramic mould casting process 25 2.3 Permanent mould casting processes 27 2.3.1 Slush casting 28 2.3.2 Low-pressure casting 28 2.3.3 Vacuum permanent mould casting 28 2.3.4 Graphite mould casting 29 V 2.3.5 Die casting 29 2.3.6 Centrifugal casting 31 2.3.6.1 True centrifugal casting 31 2.3.6.2 Semi centrifugal casting 31 2.4 Core and pattern making 32 2.4.1 Solid pattern 32 2.4.2 Split pattern 32 2.4.3 Match-plate pattern 33 2.5 Mould design and construction 33 2.6 Metal melting devices 37 2.6.1 Cupola 38 2.6.2 Air furnace (or reverberatory furnace) 39 2.6.3 Rotary melting furnace 39 2.6.4 Open hearth furnaces 40 2.6.5 Converter 40 2.6.6 Crucible furnaces 41 2.6.7 Electric furnaces 42 2.7 Temperature measurements of melts 42 2.8 Pouring devices (ladles) 42 2.9 Casting operation 44 2.10 Solidification and removal castings 44 2.11 Fettling 45 2.12 Inspection method 46 CHAPTERTHREE: THEORY, TECHNIQUES & DESIGN OF 48 METAL CASTING MOULD 3.1 Introduction 49 3.2 Gating system 49 3.2.1 Pouring basin 56 3.2.2 Sprue 58 3.2.3 Sprue base well 61 3.2.4 Choke area 61 3.2.5 Runner 65 3.2.6 Runner extension 65 VI 3.2.7 Ingates 66 3.2.7.1 Top gate 67 3.2.7.2 Bottom gate 67 3.2.7.3 Parting gate 67 3.2.7.4 Step gate 68 3.2.8 Riser 69 3.2.8.1 Risering design 71 3.3 Pouring time 80 3.4 Casting yield 82 3.5 Slag Trap Systems 83 3.5.1 Runner Extension 84 3.5.2 Whirl gate 84 3.6 Feeding Distances 84 3.7 Chills 84 3.8 Product special design considerations 86 3.8.1 Geometric simplicity 86 3.8.2 Corners 86 3.8.3 Section thicknesses 86 3.8.4 Draft 86 3.8.5 Use of cores 87 3.8.6 Dimensional tolerances and surface finish 87 3.8.7 Machining allowances 87 CHAPTER FOUR: THE FOUNDRY SET-UP 88 4.1 Introduction 89 4.2 Foundry lay-out 89 4.2.1 Die-casting machine 91 Machine Operation Data 96 4.2.1١ 4.2.1.2 Weight of casting 96 4.2.1.3 Calculation of the casting area 97 4.2.1.4 Setting of injection speed 97 4.2.1.5 Limitations 97 4.2.2 Centrifugal casting machine 98 4.2.2.1 Advantages 101 VII 4.2.2.2 Limitation 102 4.2.3 Sand mould making Machine 102 4.2.4 Vibratory mould shake 104 4.2.5 Furnaces 105 4.2.5.1 Tilting Crucible furnace 105 4.2.5.2 A stationary crucible furnace 106 4.2.6 Ovens 107 4.2.7 Foundry tools 109 4.2.7.1 Moulders shovel 109 4.2.7.2 Riddle 109 4.2.7.3 Bench rammer 109 4.2.7.4 Floor rammer 109 4.2.7.5 Bellow 109 4.2.7.6 Molder's brush 109 4.2.7.7 Swab 109 4.2.7.8 Strike bar 109 4.2.7.9 Vent wire 110 4.2.7.10 Rapping bar 110 4.2.7.11 Draw spike and screw 110 4.2.7.12 Trowels 110 4.2.7.13 Double end slick or spoon tool 110 4.2.7.14 Lifters 110 4.2.7.15 Hub tool 110 4.2.7.16 Gate cutter 110 4.2.7.17 Sprue punch 110 4.2.7.18 Flask 111 4.2.7.19 Mould board 111 4.2.7.20 Bottom board 111 4.2.7.21 Skimmer 111 4.2.7.22 Crucible and ladle 111 4.2.7.23 Tongs 111 4.2.7.24 Double end bail and single shank 111 4.2.7.25 Clamps and weights 111 VIII CHAPTER FIVE: EXPERIMENTAL WORK 112 5.1 Introduction 113 5.2 Sand casting experiment 113 5.2.1 Job no.