Idea Transcript
MOULD DESIGN AND MECHANICAL ANALYSIS OF THE CASTED MATERIAL
MOHD AZUAN BIN ABU SHAH
Thesis submitted in fulfillment of the requirements for the award of the degree of Bachelor of Mechanical Engineering with Manufacturing Engineering
Faculty of Mechanical Engineering UNIVERSITI MALAYSIA PAHANG
DECEMBER 2010
ii
UNIVERSITI MALAYSIA PAHANG FACULTY OF MECHANICAL ENGINEERING I certify that the project entitled “Mould design and mechanical analysis of the casted material” is written by Mohd Azuan Bin Abu Shah. I have examined the final copy of this project and in our opinion; it is fully adequate in terms of scope and quality for the award of the degree of Bachelor of Engineering. I herewith recommend that it be accepted in partial fulfillment of the requirements for the degree of Bachelor of Mechanical Engineering with Manufacturing Engineering.
MR. JASRI BIN MOHAMAD Examiner
Signature
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SUPERVISOR’S DECLARATION
I hereby declare that I have checked this project report and in my opinion this project report is sufficient in terms of scope and quality for the award of the Bachelor of Mechanical Engineering with Manufacturing Engineering.
Signature
:
Name of Supervisor
: MR. RAMLI BIN JUNID
Position
: LECTURER
Date
: 06 DECEMBER 2010
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STUDENT’S DECLARATION I declare that this report titled “Mould design and mechanical analysis of the casted material” is my result of my own research except as stated in the references. This t h e s i s / r e p o r t has not been accepted for any degree and is not concurrently submitted for award of other degree.
Signature
:
Name
: MOHD AZUAN BIN ABU SHAH
Id. Number
: ME08015
Date
: 06 DECEMBER 2010
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ACKNOWLEDGEMENTS
First and foremost, I wish to express my sincere appreciation to my project supervisor, Mr. Ramli Bin Junid, for constantly guiding and encouraging me throughout this study. Thanks a lot for giving me a professional training, advice and suggestion to bring this thesis to its final form. Without his support and interest, this thesis would not have been the same as presented here. I am very grateful to him for his patience and his constructive comments that enriched this research project. I would also like to acknowledge with much appreciation the crucial role of the staff in Mechanical Laboratory, for their valuable comments, sharing their time and knowledge on this research project during the project was carried out and giving a permission to use all the necessary tools in the laboratory. They have contributed towards my understanding and thoughts. In particular, my sincere thankful is also extends to all my colleagues and others who have provided assistance at various occasions. Their views and tips are useful indeed. And last, but not least thanks to my family for their continuous support and confidence in my efforts.
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ABSTRACT
This report is an outcome of the work carried out in doing and completing final year project, mould design and mechanical analysis of the casted material. Objectives of this project is to design and fabricate the mould for tensile test specimen, following ASTM E8 standard and to study the mechanical properties of the casted materials and its comparison with effect of the cooling rate between water, oil and air. Materials that have been used for mould is mild steel and for casted material is aluminum alloy. Overall, this project was run based on four main steps; design using Solid Work, running a simulation on Master CAM, fabricates using CNC Milling Machine, and finally casting process. Each sample was then tested by Rockwell hardness in order to study the effect of the cooling media to the hardness of casted material for all three cooling media, water, oil and air. It project was done by testing at the outer surface and inner surface of the casted aluminum alloys. The higher value for outer surface hardness test is 49.10 HRB and the higher value for inner surface hardness test is 37.72 HRB. The result shows the hardness of casted material immersed in water has higher value compared to oil and air. Water has proved to be the best mediums for cooling rate compare to oil and air medium. The hardness of aluminium increases with the increasing of cooling rate. Cooling rate decreases with distance from the quenched end, and the hardness also decreases.
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ABSTRAK
Laporan ini ialah satu hasil kerja dijalankan dalam melakukan dan menyiapkan projek tahun terakhir, membentuk reka bentuk dan analisis mekanik bahan dicor. Tujuan dari projek ini adalah untuk merancang dan membuat cetakan untuk spesimen uji tarik, mengikuti ketetapan ASTM E8 dan untuk mempelajari sifat mekanik bahan dicor dan perbandingannya dengan kesan kadar penyejukan antara air, minyak dan udara. Bahanbahan yang telah digunakan untuk cetakan adalah keluli lembut dan bahan dicor adalah paduan aluminium. Secara keseluruhan, projek ini dijalankan berdasarkan empat langkah utama; mereka bentuk menggunakan Solid Work, menjalankan simulasi menggunakan perisian CAM, mereka menggunakan mesin kisar CNC, dan akhir sekali adalah proses tuangan. Setiap sampel yang diuji oleh kekerasan Rockwell untuk mempelajari pengaruh media pendinginan untuk bahan dicor untuk ketiga-tiga media pendinginan iaitu melalui air, minyak dan udara. Projek ini telah dijalankan dengan melakukan pengujian pada permukaan luar dan permukaan dalam dari gabungan aluminium dicor. Nilai yang tertinggi untuk ujian kekerasan pada permukaan luar ialah 49.10 HRB dan nilai tertinggi untuk ujian kekerasan permukaan dalam ialah 37.72 HRB Keputusan kajian menunjukkan kekerasan bahan dicor direndam dalam air mempunyai nilai lebih tinggi berbanding dengan minyak dan udara. Air telah terbukti menjadi media terbaik untuk membandingkan kadar penyejukan diantara minyak dan medium udara. Kekerasan aluminium meningkat dengan meningkatnya kadar penyejukan. Kadar penyejukan berkurangan dengan jarak dari menghilangkan akhir, dan kekerasan juga berkurangan.
.
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TABLE OF CONTENTS
Page EXAMINER’S DECLARATION
ii
SUPERVISOR’S DECLARATION
iii
STUDENT’S DECLARATION
iv
DEDICATIONS
v
ACKNOWLEDGEMENTS
vi
ABSTRACT
vii
ABSTRAK
viii ix
TABLE OF CONTENTS LIST OF TABLES
xiii
LIST OF FIGURES
xiv
LIST OF SYMBOLS
xviii xix
LIST OF ABBREVIATIONS
CHAPTER 1
CHAPTER 2
INTRODUCTION
1
1.1
Project Background
1
1.2
Problem Statement
2
1.3
Project Objectives
3
1.4
Project Scopes
4
LITERATURE REVIEW
5
2.1
Tensile Testing Specimen (ASTM E8)
5
2.2
Engineering Design
7
2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6 2.2.7 2.2.8
Gating System and Mold Design Insure that have Adequate Material Consider the Superheat Insulate Risers Consider V/A Ratios Heat Masses Sections of the Casting Consideration to L, T, V, Y and Junctions
7 8 8 8 9 9 10 10
x
2.2.9 2.2.10 2.2.11 2.2.12 2.2.13 2.2.14 2.3
11 11 12 13 13 14
CAD/CAM
15
2.3.1
16
G-codes and M-codes
2.4
CNC Milling Machine
17
2.5
Introduction of Metal Casting
18
2.6
Types of Casting Process
19
2.6.1 2.6.2 2.6.3
19 19 19
2.7
2.8
2.9
Permanent Pattern Permanent Mould Expandable Mould and Pattern
Die Casting Materials
20
2.7.1 2.7.2
21 21
Common Alloys in Casting Material Selection
Basic Factors in Casting Process
22
2.8.1 2.8.2 2.8.3
22 23 23 23 23 24 24 25 25 25 26
2.8.4 2.8.5 2.8.6
CHAPTER 3
Prevent Planes of Weakness Reduce Turbulence Connection between Riser and Casting Tapered Down Sprue Runner Geometry of Conventional Mould Gates
Mould Cavity Melting Process Pouring of the Metal a) Pouring Temperature b) Pouring Rate c) Turbulence d) Fluidity e) Pouring Techniques Solidification Process Mould Removal Finishing Operation
Rockwell Hardness Test
26
METHODOLOGY
28
3.1
Introduction
28
3.2
Literature Review
30
3.3
Design the Mould
30
3.3.1 3.3.2
31 32
Introduction to Solid Works Mould Design
xi
3.3.3 3.4
33
Gating System Calculations
35
3.4.1 3.4.2 3.4.3 3.4.4 3.4.5 3.4.6 3.4.7
36 37 38 38 39 40 40
Weight of Product Gating Ratio Pouring Time Metal Velocity Ingate Sectional Runner Sectional Sectional Sprue
3.5
Material Selection
41
3.6
Simulation in Master CAM
43
3.6.1
46
3.7
G Codes and M Codes
Machining Process
47
3.7.1 3.7.2
47 47
3.7.3
CHAPTER 4
Drawing in Solid Work
Introduction of CNC Machining General Procedure to CNC Machining Operation Machining Operation
48
3.8
Casting Process
53
3.9
Cooling Process
57
3.10
Hardness Test
58
RESULT AND DISCCUSIONS
60
4.1
Introduction
60
4.2
Result of Mould Fabrication Process
61
4.3
Final Product
62
4.4
Analysis for Rockwell Hardness Test
65
4.4.1 4.4.2 4.4.3 4.4.4 4.4.5
65 65 66 67 68
4.4.6 4.5
Outer Surface Hardness Data Inner Surface Hardness Data Graph of Outer surface Hardness Test Graph of Inner Surface Hardness Test Comparison between Outer and Inner Hardness Test Graph of Comparison between Outer and Inner Surface Hardness Test
70
Shape Analysis of the Casted Material
72
4.5.1 4.5.2 4.5.3
72 73 74
Short Casting or Misruns Shrinkage Crack
xii
4.5.4 4.5.5 4.5.6 4.6
CHAPTER 5
Cold Shut Flash Porosity
75 76 77
Summary
78
CONCLUSION
80
5.1
Introduction
80
5.2
Conclusion
80
5.3
Recommendations
81
REFERENCES
82
APPENDICES A
Project Planning (Gantt Chart)
84
B
Solidwork Drawing
86
xiii
LIST OF TABLES
Table No.
Title
Page
2.1
Detail Dimension for Tensile Test Specimen
6
2.2
The Minimum Section Thickness and Minimum Draft
20
3.1
Gating Ratios
37
3.2
Type of Tooling
49
4.1
Outer Surface Hardness Data
65
4.2
Inner Surface Hardness Data
65
4.3
Data of Hardness Test With Water as Cooling Media
68
4.4
Data of Hardness Test With Oil as Cooling Media
69
4.5
Data of Hardness Test With Air as Cooling Media
69
4.6
Data of Different Value for Each Cooling Media
69
xiv
LIST OF FIGURES
Figure No.
Title
Page
2.1
Specimen for Tensile Test
6
2.2
Specimen Preparation according to ASTM Specifications
6
2.3
V/A Ratio
9
2.4
Heat Mass and Riser
9
2.5
Sections of the Casting
10
2.6
Consideration to L, T, V, Y and Junctions
10
2.7
Prevent Planes of Weakness
11
2.8
Reduce Turbulence
12
2.9
Connection between Riser and Casting
12
2.10
Positioning Gates to Improve Flow
14
2.11
CNC Milling Machine (HAAS)
18
2.12
Rockwell Principle
26
3.1
Project Flow Chart
29
3.2
Cope and Drag Sketching
30
3.3
Gating System Sketching
31
3.4
Gating System Sketching
31
3.5
3D Drawing of Right Side Vertical Mould
33
3.6
3D Drawing of Left Side Vertical Mould
33
3.7
2D Drawing of Right Side Vertical Mould
34
3.8
Isometric View
34
3.9
2D Drawing
35
3.10
Raw Material for Mould (Mild Steel)
42
xv
3.11
Pocket Process for Riser
43
3.12
Pocket Process for Runner
43
3.13
Center Drill and Drilling Process for Well
44
3.14
Pocket Process for Ingate
44
3.15
Pocket Process for Part
45
3.16
Surface Finish Parallel Process for Sprue
45
3.17
G and M Codes of CNC Milling Process
46
3.18
CNC Milling Machine
48
3.19
Facing Process
49
3.20
Pocket Process
50
3.21
Pocket Process
50
3.22
Center Drilling Process
51
3.23
Drilling Process
51
3.24
3D Pocket Process
52
3.25
Surface Grinding Process
52
3.26
Mould Clamping
54
3.27
Temperature Measure using Infrared Thermometer
55
3.28
Preheating Process
55
3.29
Pouring Process
56
3.30
Pouring Process
56
3.31
Cooling Media using Water
57
3.32
Cooling Media using Oil
57
3.33
Cooling Media using Air
57
3.34
Specimen Size
58
xvi
3.35
Outer Surface Hardness Test
59
3.36
Inner Surface Hardness Test
59
4.1
Complete Mould
61
4.2
Top View
61
4.3
Finishing Process using Surface Grinding Machine
62
4.4
Finishing Process using Air Grinder
62
4.5
Mould and Casting Product
63
4.6
Infrared Thermometer
63
4.7
Casting Product
64
4.8
Tensile Test Specimen
64
4.9
Graph of Outer Surface Hardness Test
66
4.10
Graph of Inner Surface Hardness Test
67
4.11
Graph of Hardness Test with Water as Cooling Media
70
4.12
Graph of Hardness Test with Oil as Cooling Media
70
4.13
Graph of Hardness Test with Air as Cooling Media
71
4.14
Temperature Mould 200 ◦C
72
4.15
Temperature Mould 350 ◦C
72
4.16
Shrinkage Problem
73
4.17
Shrinkage Problem
73
4.18
Cracking at the well
74
4.19
Cold Shut at the Tensile Specimen
75
4.20
Flash Defect
76
4.21
Flash Defect
76
4.22
Gas Porosity Defect
77
4.23
Gas Porosity Defect
77
xvii
6.1
3D Drawing of Complete Mould
86
6.2
Sheet Drawing of Complete Mould
87
6.3
3D Drawing of Left Mould
88
6.4
Sheet Drawing of Left Mould
89
xviii
LIST OF SYMBOLS Millimeter Megapascal Gigapascal Percent Brinell Hardness Number HR
Rockwell Hardness Number
D
Diameter of Steel Ball Second Pound of Force Stress Minor Load Major Load
F
Total Load Density
A
Area
V
Volume Depth of Penetration Instantaneous Length Original Length Modulus of Elasticity
xix
LIST OF ABBREVIATIONS AA
Aluminum Association
AISI
American Iron and Steel Institute
ASTM
American Society for Testing and Material
CAD
Computer Aided Design
CAM
Computer Aided Manufacturing
CNC
Computer Numerical Control
FKM
Fakulti Kejuruteraan Mekanikal
HPCC
High Precision Contour Control
HRB
Hardness Rockwell Brinell
ISO
International Organization for Standardization
NC
Numerical Control
RISC
Reduced Instruction Set Computer
RPM
Rotation Per Minutes
UMP
Universiti Malaysia Pahang
V/A
Volume per Surface Area
2D
Two Dimension
3D
Three Dimension
1
CHAPTER 1
INTRODUCTION
1.1
PROJECT BACKGROUND
Casting is a manufacturing process where a solid is melted, heated to proper temperature (sometimes treated to modify its chemical composition), and is then poured into a cavity or mold, which contains it in the proper shape during solidification. Thus, in a single step, simple or complex shapes can be made from any metal that can be melted. The resulting product can have virtually any configuration the designer desires. Since metal casting involves working with metal in its molten form, the process can be dangerous if undertaken by the reckless or ill informed. The melting points of several metals are well above 1,000 degrees Fahrenheit, or 530 degrees Celsius. It is vital that anyone wanting to work with metal casting take all the proper precautions.
Casting has marked advantages in the production of complex shapes, parts having hollow sections or internal cavities, parts that contain irregular curved surfaces (except those made from thin sheet metal), very large parts and parts made from metals that are difficult to machine. Because of these obvious advantages, casting is one of the most important of the manufacturing processes.
2 Today, it is nearly impossible to design anything that cannot be cast by one or more of the available casting processes. Metal casting requires specialized equipment, knowledge, and some creativity. While metal casting is used on an Industrial level as the process cuts cost and proves to be highly efficient. However, as in all manufacturing techniques, the best results and economy are achieved if the designer understands the various options and tailors the design to use the most appropriate process in the most efficient manner. The various processes differ primarily in the mold material (whether sand, metal, or other material) and the pouring method (gravity, vacuum, low pressure, or high pressure). All of the processes share the requirement that the materials solidify in a manner that would maximize the properties, while simultaneously preventing potential defects, such as shrinkage voids, gas porosity, and trapped inclusions. Based on that case, the project title was proposed is mould design and mechanical analysis of the casted material. This project involves the designing process, simulation process, fabrication process and analysis process. The project start from design the mould using computer aided design (CAD) software and then simulation using master cam (CAM) software. After that the project continues with fabrication the mould using CNC Milling Machine and next process is mould casting. The finally is mechanical analysis process for the product cast. At the end of the project, all the process method will combine to study and investigate the defects of gases, gating system and mold design and material selection in metal casting and other defects.
1.2
PROBLEM STATEMENT As in all metal casting process, certain guidelines and design principles
pertaining to casting have been developed over many years. Although these principles have been established primarily through experience, analytical methods, process simulation and modeling, and computer aided design and manufacturing techniques have all come into wide use as well, thus improving productivity and the quality of castings and resulting in significant cost savings.
3 However, products that are produced with casting process still have defective. In most cases a given mold design will produce mostly well with some defective. It is very difficult for a mold to produce no defective parts and some defective ones. There are many defective that are found in products primarily due to gassing, pouring method, size of risers and etc. However, this kind of causes is difficult to control since process of casting is a hands-on process by human itself and not machine where it involves pouring the melted material into mould. Thus, in this project, the system for casting in terms of gating system and risers will be designed and calculated purposely to reduce the defects of part to be casted. Furthermore, the study about the mechanical properties of the casted material has not been an interested topic among researchers. Hence, investigation to the changes of aluminum mechanical properties after the casting process will be examined in this project.
1.3
PROJECT OBJECTIVES
Basically, the specific objectives of this project are:
1. To design and fabricate the mould for tensile test specimen, ASTM E8. 2. To study the mechanical properties of the casted materials by quench the aluminum alloys to different cooling media which are water, oil and air.
4 1.4
PROJECT SCOPES
This project will be carried out by using specific software and machine in the process of designing and fabricating the mould of casting. The dimension of the casted dog-bone shape for the tensile test specimen will be according to ASTM standard E8 as shown in Figure 2.1 in chapter 2. The material and hardware to be used to carry out this project is listed as follows:
1. Types of material to be used in this project are restricted to only aluminum for the casted material and mild steel as the mould. 2. The design of mould is according to dog-bone shape standard ASTM E8 and it will be done by using Solid Work as the design software. 3. Master CAM software used to simulate the machining process of mould fabrication. 4. Fabrication process of the mould has done by using CNC milling machine.
5
CHAPTER 2
LITERATURE REVIEW
2.1
TENSILE TESTING SPECIMEN (ASTM E8)
Consider the typical tensile test specimen is shown as Figure 2.1. It has enlarged ends or shoulders for gripping. The important part of the specimen is the gage section. The cross sectional area of the gage section is reduced relative to that of the remainder of the specimen so that deformation and failure will be localized in this region. The gage length is the region over which measurements are made and is centered within the reduced section. The distances between the ends of the gage section and the shoulders should be great enough so that the larger ends do not constrain deformation within the gage section, and the gage length should be great relative to its diameter (Davis Joseph, 2004).
There are various ways of gripping the specimen, some of which are illustrated in Figure 2.3. The end may be screwed into a threaded grip, or it may be pinned; butt ends may be used, or the grip section may be held between wedges. The most important concern in the selection of gripping method is to ensure that the specimen can be held at the maximum load without slippage or failure in the grip section. Bending should be minimized (Davis Joseph, 2004).
6
Figure 2.1: Specimen for tensile test Source: Davis Joseph, 2004
Figure 2.2: Specimen preparation according to ASTM specifications Source: Davis Joseph, 2004
Table 2.1: Detail Dimension for Tensile Test Specimen No. 1 2 3 4 5 6 7 8
Item Lt, Total Length Lg, Grip Length Lo, Gauge Length Lc, Parallel or Reduce Section R, Radius a, Thickness b, Gauge width c, Grip width
Dimension Min 8" (20.32cm) Min 2" (5.08cm) 2.000" ± 0.0005" (5.08 ± 0.0127cm) Min 2.25" (5.715cm) Min 0.5" 0.2" (0.4cm) 0.500" ± 0.01" (1.27 ± 0.0254cm) Approx. 0.75" (1.905cm)
Source: Davis Joseph, 2004