Fatigue analysis on die insert of connecting rod in closed die forging process.
FATIGUE ANALYSIS ON DIE INSERT OF CONNECTING ROD
IN CLOSED DIE FORGING PROCESS
By
MOHD AMRI BIN SULAIMAN
Project Paper submitted to Department of Mechanical and Manufacturing, Faculty of
Engineering, University of Putra Malaysia, in partially fulfilment of the requirements
for the Degree of Master in Manufacturing System Engineering.
May 2006
Abstract of the project to the Department of Mechanical and Manufacturing, Faculty of
Engineering, University of Putra Malaysia in partially fulfillment of the requirement for the
Degree of Master in Manufacturing System Engineering.
Abstract:
FATIGUE ANALYSIS ON DIE INSERT OF CONNECTING ROD IN
CLOSED DIE FORGING PROCESS
By
MOHD AMRI SULAIMAN
Supervisor: Prof. Dr. Abdel Magid Salem Hamouda
Faculty: Engineering
To meet the increasing demand for more accurate forged products with a higher added value
and of higher material yield, precision forging-related technology has been making
remarkable progress.
In this
regard,
research
and development on CAD/CAM/CAE (computer-aided
design/computer-aided manufacturing/computer aided engineering) systems for practical use
have been vigorously promoted. CAD/CAM/CAE technology has already established itself
in the fields of designing and manufacturing sheet metal dies and is extensively used in the
aircraft and automobile industries. The CAD/CAM/CAE system developed and operated for
the hot forging of connecting rod.
In conventional hot forging of connecting rods, the material wasted to the flash accounts
approximately 20-40% of the original workpiece. In order to reduce the cost of forged
products, the forging must be performed in a closed cavity to obtain near-net or net shape
parts. In flash less forging, the volume distribution of the preform must be accurately
controlled to avoid overloading the dies and to fill the cavity. Additionally, the preform
must be simple enough to be mass-produced.
This work used the CAD/CAM/CAE system for fatigue analysis on die insert of connecting
rod in closed die forging process. The implementation of this study consists of five stages; i)
modelling part (connecting rod) using CAD software (Solidworks 2005), ii) preliminary die
insert design, iii) stress-strain simulation of die insert, iv) die insert fatigue analysis and
lifetime, and v) developed CNC code programming for die insert. In the first stage,
Solidworks 2005 software was used for modeling part (connecting rod). The second stage,
again CAD software (Solidworks 2005) was used to model the primary design of the die
insert based on the shape of the forged part. In third stage, simulated the die inserts of
connecting rod and analysed the maximum stress-strain applied on the die insert and the
requirement of load to perform the forging operation. Meanwhile in fourth stage,
determination fatigue analysis and lifetime on die insert was done by comparing the values
from S-N curve and maximum stress-strain value from FEA result. In the last stage,
Unigraphics software was used to develop CNC machining code or known GM code for
fabricating the die inserts.
11
Abstrak projek yang dikemukakan kepada Jabatan Mekanikal dan Pembuatan, Fakulti
Kejuruteraan, Universiti Putra Malaysia sebagai memenuhi sebahagian dari keperluan untuk
Ijazah Sarjana Kejuruteraan Sistem Pembuatan.
Abstrak:
ANALISIS KELEMAHAN TERHADAP SELITAN ACUAN ROD
PENYAMBUNG DALAM PROSES TEMPA ACUAN TERTUTUP
Oleh
MOHD AMRI SULAIMAN
Penyelia: Prof. Dr. Abdel Magid Salem Hamouda
Fakulti: Kejuruteraan
Bagi memenuhi peningkatan terhadap permintaan kepada barang tempa yang lebih jitu dan
berkualiti tinggi, proses teknologi berkaitan kejituan tempaan telah begitu menonjol.
Sehubungan dengan itu, pembangunan dan penyelidikan sistem CAD/CAM/CAE untuk
tujuan praktikal amat digalakkan. Teknologi CAD/CAM/CAE telah lama diwujudkan
terutamanya dalam rekabentuk dan pembuatan acuan kepingan logam dan ia digunakan
secara meluas di
dalam
indusri pembuatan kapal
terbang
dan
kereta.
Sistem
CAD/CAM/CAB ini juga telah dilaksanakan dan diguna pakai dalam pembikinan rod
penyambung.
lll
Di dalam proses penempaan panas rod penyambung secara normal, pembaziran bahan
logam sering berlaku kira-kira 20 - 40 peratus daripada bahan logam asal. Oleh itu, untuk
mengurangkan kos produk tempaan, proses tempaan mesti dilakukan pada acuan tertutup
untuk mendapatkan bentuk yang seakan hampir dari bentuk asal. Di dalam proses tempaan
kurang lebihan bahan, jumlah pengaliran logam mestilah dikawal dengan tepat bagi
mengelakkan lebihan bebanan kepada acuan. Secara ringkasnya, prabentuk hendaklah sesuai
untuk pengeluaran secara besar-besaran.
Kajian ini melibatkan penggunaan sistem CAD/CAM/CAE untuk menganalisis kelemahan
selitan acuan rod penyambung dalam proses tempa acuan tertutup. Perlaksanaan kajian ini
terdiri daripada lima peringkat; i) merekabentuk rod penyambung menggunakan program
CAD, (Solidworks 2005), ii) persediaan utama merekabentuk selitan acuan, iii) Simulasi
ketegangan selitan acuan, iv) menentukan jangka hayat dan analisis kelemahan selitan
acuan, dan v) membangunkan kod program CNC untuk selitan acuan. Pada peringkat
pertama, program Solidworks 2005 digunakan untuk merekabentuk rod penyambung. Pada
peringkat kedua, sekali lagi program Solidworks 2005 digunakan untuk merekabentuk
selitan acuan berdasarkan bentuk rod penyambung. Bagi peringkat ketiga pula, simulasi
selitan acuan rod penyambung dan analisis ketegangan maksimum terhadap selitan acuan
serta bebanan yang diperlukan untuk proses tempaan ini. Seterusnya peringkat ke empat,
menentukan jangka hayat dan analisis kekuatan-kelemahan selitan acuan dengan membuat
perbandingan nilai dari graf S-N dan keputusan dari ' finite element analisis' (FEA). Pada
peringkat terakhir pula, program Unigraphics digunakan untuk membangunkan kod
pemesinan CNC atau dikenali GM-code untuk fabrikasi selitan acuan.
lV
ACKNOWLEDGEMENT
First of all I would like to appreciate to the Kolej Universiti Teknikal Kebangsaan Malaysia,
KUTKM as an employer and gave approval to me for furthering my Master study. Also
thanks to the Jabatan Perkhidmatan Awam, JPA as sponsorship in this study.
Many industry person and academicians from various sources have contributed generously
to the completion of this case study. I greatly acknowledge my supervisor Prof. Dr. A.
Magid Hamouda, lecturer in the Department of Mechanical and Manufacturing Engineering
for his trust, sharing ideas and supportive effort all these while. I would also like to take this
opportunity to thank my examiner, Assoc. Prof. Dr. Wong Shaw Voon for his effort and
guidance in correcting this case study.
I would like to thanks my family, who always has been with me supporting me even in the
hardest of time, my dear friends whom have been very helpful and encouraging.
This case study is the combination of computer aided design (CAD) for modeling purpose,
computer of manufacturing (CAM) for G-code program and fabrication purpose and
computer aided engineering (CAE) for finite element analysis purpose. For this I would also
like to thank the individual stated below for their time to share information and ideas.
Mr. Amir Radzi
Engineer Researcher,
National CADCAM, Sirim Berhad.
Mr. Jefridi Mat Siman
Engineer Researcher,
Machinery and Tooling Technology Program, Sirim Berhad.
v
Mr. Goh Kok Ming
Production Engineer,
Metal Techs Sdn. Bhd,
Ayer Keroh, Melaka.
Mr. Jaafar Lazim
Senior Technician,
Faculty of Manufacturing,
Kolej Universiti Teknikal Kebangsaan Malaysia.
vi
APPROVAL
This project submitted to the Department of Mechanical and Manufacturing, Faculty of
Engineering, University of Putra Malaysia has been accepted as a partial fulfillment of the
requirements for the Degree of Master of Manufacturing System. The members of the
examinations committee are as below;
fA
Ｍﾷ Ｍ ｾＭ
Ｍ
(;2
Supervisor, PhD
Prof. Dr. A. Magid Hamouda
Department of Mechanical and Manufacturing,
Faculty of Engineering,
University of Putra Malaysia
Examiner, PhD
Assoc. Prof. Dr. Wong Shaw Voon
Department of Mechanical and Manufacturing,
Faculty of Engineering,
University of Putra Malaysia
vii
DECLARATION
I hereby declare that the project paper is based on my original work except for quotations
and citations that have been duly acknowledge. I also declare that it has not been previously
or concurrently submitted for any other degree of university or other institutions.
MOHD AMRI BIN SULAIMAN
viii
List of Contents
Page
ABSTRACT
ABSTRAK
111
ACKNOWLEDGEMENTS
v
APPROVAL SHEETS
Vll
DECLARATION FORM
V111
LIST OF CONTENTS
IX
LIST OF FIGURES
X111
LIST OF TABLES
xv
CHAPTER
1
2
INTRODUCTION
Forging for connecting rod
2
Objective
4
Scope of studies
5
Project organizations
5
LITERATURE REVIEW
7
Forging
7
Comparison forging with other processes
8
Why are forging so prevalent
15
Closed die forging
19
Requirements for closed die forging
20
Case Study Flashless Forged Connecting Rod
21
ix
3
4
Process details Closed-die forging
24
Process requirements
27
Open die forging
29
Hot forging
30
Die life service
30
Die service life based on plastic deformation
31
A brief history of the Finite Element Method
32
The history ofMSC.NASTRAN
33
The overview ofMSC.NASTRAN
35
Connecting Rod in the engine block
37
Basic steps in the finite element method
39
METHODOLOGY
40
Stage I: Modelling part using CAD software (Solidworks 2005)
41
Stage 2: Preliminary die insert design
42
Stage 3: Stress-strain simulation of die inserts
43
Stage 4: Die inserts fatigue analysis and lifetime
43
Stage 5: Developed CNC code for the die inserts
43
COMPUTER AIDED DESIGN-CAD: Modeling Die Insert
44
Computer Aided Design, (CAD)
44
Solidworks 2005 software for modelling
44
Die insert drawing and dimensions
46
Material properties for die insert
48
Connecting rod drawings, dimensions and material
50
Billet dimensions
52
x
5
6
COMPUTER AIDED ENGINEERING-CAE: Finite Element
Analysis on Die Inserts of Closed Die Forging
54
Computer Aided Engineering, (CAE)
54
MSC.NASTRAN software
55
Die Inserts analysis
56
Mesh Element
56
Pressure Load
57
Stress-Strain
58
Displacement on Die Inserts
59
Constraint Force on Die Inserts
59
S-N Curve for Carbon Steels (AISI 1055)
61
Fatigue Analysis of Die Inserts
62
Comparison values between Finite Element Analysis and S-N curve
63
COMPUTER AIDED MANUFACTURING-CAM: Die Insert of
Closed Die Forging
65
Computer Aided Manufacturing, (CAM)
65
Overview Unigraphics software
65
Tool Path
67
Cavity Mill
69
GM code
71
XI
7
8
RESULTS AND DISCUSSIONS
72
Determination Fatigue Analysis of Die Insert
72
Billet Dimensions
75
CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE WORK
The Conclusions of Project
76
Project Contribution
78
System Limitations
78
Recommendations for Future Work
79
REFERENCES
80
APPENDICES
Appendix 1: In Part of CNC code for the Machining Operation
Required to Produce the Die Insert
82
Appendix 2: A diskette that contain Full CNC code for Die Insert
92
Fabrication
BIODATA OF AUTHORS
93
Xll
List of Figures
Page
Figure
1. Connecting rod
2
2. Closed die forging with and without flash
3
3. Closed die forging
19
4. Comparison between conventional forging and closed die forging
21
5. Closed die forged connecting rod
22
6. Stages in forging a connecting rod
23
7. A heated blank between 2 halves of a die
24
8. Compressive stroke squeezes the blank into the die
24
9. Part ejected using an ejector pin
25
10. Waste material (flash)
25
11. Connecting rod location in the engine block
38
12. Forging industry
38
13. Industrial - Closed Die Forging
38
14. Flowchart of the methodology
41
15. Connecting rod
42
16. Die insert
43
17. Cavity dimensions (in mm)
46
18. Cavity depth for Lower Die Insert (in mm)
46
19. Lower Die Insert dimensions (in mm)
47
20. Cavity depth for Upper Die Insert (in mm)
47
21. Upper Die Insert dimensions (in mm)
47
22. The Upper die insert and lower die insert at open position
48
Xlll
23. Product (connecting rod) dimensions (in mm)
50
24. Billet dimensions with offset 2% (in mm)
53
25. Mesh element on die insert
56
26. Pressure load applied on the cavity profile
57
27. Stress-strain
58
28. Displacement on the die insert (in mm)
59
29. Constraints force on die inserts
60
30. Constraints force on bottom die inserts
60
3 1. S-N curve for carbon steel (AISI 105 5)
61
32. S-N curve show comparison between O"max and O"se
64
33. The Create Operation
67
34. Tool paths for first cavity milling
68
35. Cavity Mill part
69
36. Cavity Mill Parameters Setting
70
37. S-N curve show comparison between
O"max
and O"se
74
38. Stress-strain values (in N/m 2) for carbon steel AISI 1055 die insert
74
39. The thickness of billet (in mm)
75
XIV
List of Tables
Table
Page
I. Comparison between forging and welding/fabrication
9
2. Comparison between forging and casting
IO
3. Comparison between forging and powder metallurgy
11
4. Comparison between forging and reinforced plastic and composites
12
5. Comparison between forging and machined steel bar/plate
13
6. Advantages of forging compare to other process
14
7. Specifications of the Closed die forged connecting rod
23
8. AISI 1055
49
9. Composition of AISI I 055
49
I 0. Mechanical properties of AISI 1055
49
xv
Chapter 1
Introduction
1.1 Introduction
If the weight of a connecting rod (see Fig. 1) can be reduced while increasing its strength,
an automobile's fuel efficiency will be improved. Currently, steel connecting rods are used
in passenger cars. However, some manufacturers have attempted to use alternative lighter
materials. Recently, various composite materials based on aluminum have been considered,
but not yet successfully adopted, for automotive engines. The main reasons are that these
materials are not strong enough, or when strong enough, are too expensive.
Flash less forging offers the possibility of producing aluminum composite connecting rods
at competitive costs. The design of flash less forging processes is more complex than the
design of conventional closed die forging with flash. Therefore, in order to accelerate the
development of the manufacturing process as well as to reduce the development costs, a new
design method must be developed and applied. The finite element method (FEM) offers the
possibility to design the entire manufacturing process on a computer. This leads to a
reduction of the cost and time in process and tool design, tool manufacturing, and die tryout. In addition, it is possible to modify the process conditions in the simulation to find the
best manufacturing conditions for a product.
1
Figure 1: Connecting rod
1.2 Forging for connecting rod;
In the forging of connecting rods, three main methods are employed. The first method
consists of making a rough pre-form from a non-porous billet and hitting it several times in
a press until the final shape is obtained (Figure 2a). This method results in 20-40% of the
material to be wasted as flash. A major advantage of the closed-die forging with flash is that
the volume of the pre-form can vary within a wider range than for flash less forging. This
makes it easier to continuously manufacture products with the same quality (3].
However, a trimming process is necessary to remove the existing flash . The second method
is net shape flash less forging (Figure 2b). During this process the pre-form is totally
enclosed in the die cavity so that no flash formation is allowed. There is no material waste
as in impression forging. However, tight volume control of the pre-form is necessary to
insure filling of the cavity and to avoid overloading the tooling. The third method, which is
widely used, is hot forging of powder metallurgy pre-forms. This method yields virtually no
material waste and produces near-net shape products. However, the metal powder is '
expensive compared to conventional materials.
2
In principle, forging operations are non-steady state processes, in which the deformation of
the material takes place under three-dimensional stress and strain conditions. The material
flow depends mainly on the following;
I. geometry of the cavity;
2. geometry of the flash opening;
3. initial and intermediate billet geometry;
4. percentage of flash ;
5. heat transfer between the tooling and the billet;
Forging
Flash less
Forging
ｷｩｾｨ＠
Flash
Forging with
Flash
ｆｬ ｡ｳ
ｆｯ
ｲ ｾＱｧ＠
ｨｬ ･ｳｾ＠
I
I
I
Lower
Die
I
· Lower
Punch
Sta rt of Stroke
End of Stroke
(b)
(a)
Figure 2: Closed die forging with and without flash
Thus, the requirements to perform a successful flashless forging process are:
I. The volume of the initial pre-form and the volume of the cavity at the end of the ,
process must be the same.
2. There must be neither a local volume excess nor a shortage, which means that the
mass distribution and positioning of the pre-form must be very exact.
3. If there is a compensation space in the dies, the real cavity must be filled first.
3
1.3 Objective of the study
Currently most finite element codes that simulate billet-forming processes consider only
plane-strain or axisymmetric deformations. Since many industrial parts such as connecting
rods have very complex geometries, the metal flow is three-dimensional and cannot be
properly modeled with a two-dimensional approximation. This means that a three
dimensional simulation of the manufacturing process must be performed to get adequate
results.
For this study, it is focusing on simulation non-steady process using a finite element method
(MSC.NASTRAN) in order to better understanding of structural and fatigue analysis on the
closed die forging. The main product to study is connecting rod that most using in
automotive industry. Besides, the goals of the study are;
);;>
To develop a finite element model of die insert for connecting rod in closeddie forging process.
);;>
To determine fatigue strength material analysis and cycle lifetime of die
insert.
);;>
To developed the CNC code for the die insert using Unigraphics software.
4
1.4 Scope of study
There are many finite element analysis techniques on closed die forging, for the
development of this project, it only concentrated on fatigue strength material analysis of the
die insert design using the MSC.NASTRAN software. Meanwhile the Solidworks 2005 and
Unigraphic software will be used for modeling and CAM purpose. Currently there have
some stages of connecting rod manufacture such as blank, edging, blocking and finishing
but in this project, it only highlighted on the final stage (finishing).
1.5 Project organization
This project consists of eight chapters:
Chapter 1: Introduction of forging for connecting rod, objective and scope of this study.
Chapter 2: Reviews on the literature from journal, books and internet. The area covered
including types of forging, requirements of closed die forging, process detail of closed die
forging, material forged, die life service, history of finite element analysis, history of
NASTRAN software and basic steps in the finite element analysis.
Chapter 3: Describe methodology in this study to do the modeling, simulation, analysis and
developed CNC code.
Chapter 4: Modeling the connecting rod and die insert by using CAD software, Solidworks
2005.
5
Chapter 5: Finite Element Analysis on Die Inserts of Closed Die Forging, by using finite
element software, MSC.NASTRAN.
Chapter 6: Developed CNC machining program or known as GM code for die insert
fabrication purpose.
Chapter 7: Results on of the project and discussions.
Chapter 8: Conclusion of the project and recommendations for future works.
6
Chapter 2
Literature review
2.1 Forging
Forging is defined as the process in which metal is plastically deformed with application of
temperature and pressure. It is used to change not only the shape but also the properties of
the metal because it refines the grain size and therefore improves its structure [2]. Forging is
a cost-effective way to produce net-shape or near-net-shape components. Forged parts are
used in high performance, high strength and high reliability applications where tension,
stress, load and the human safety are critical considerations. They are also employed in a
wide range of demanding environments, including highly corrosive and extreme
temperatures and pressures.
Various parameters such as complexity of the part, friction between dies and workpiece,
type of press, die and workpiece temperature, material of workpiece governs the forging
process. Forging process is said to be successful if die cavity is completely filled and stress
in the workpiece is less than ultimate stress corresponding to the workpiece material, with
minimum force .
Forging is the controlled deformation of metal into a specific shape by compressive forces.
In year 8000 B.C. forging process are evolved from the manual art of simple blacksmithing.
Then a series of compressive hammer blows performs the shaping or forging of the part.
Now, modem forging uses machine driven impact hammers or processes, which deform the
workpiece by controlled pressure [1].
7
The forging process is superior to casting in that the parts formed have denser
microstructures, more defined grains patterns, and less porosity, making such parts much
stronger than casting. All metals and alloys are forgeable, but each will have a forgeability
rating from high to low or poor.
The factors involved are the material's composition, crystal structure and mechanical
properties all considered within a temperature range. The wider the temperature range, the
higher the forgeability rating. Most forging is done on heated workpieces. Cold forging can
occur at room temperatures. The most forgeable materials are aluminum, copper, and
magnesium. Lower ratings are applied to the various steels, nickel, and titanium alloys. Hot
forging temperatures range from 93°C (200°F) to 1650°C (3000°F) for refractory metals [6].
2.2 Comparison forging with other processes
There are some processes in forming and shaping part such as forging, casting, welded or
fabrication, machined steel bar, powder metallurgy, reinforced plastics and composites. All
of these processes have their own characteristics, advantages and disadvantages. Here
comparison some characteristics such as strength of the part (grain oriented), cost effective,
material savings, design flexibility, simplified production, and part inspections, between
forging and other process are made. Below Table 1-6 have shown this comparison.
8
IN CLOSED DIE FORGING PROCESS
By
MOHD AMRI BIN SULAIMAN
Project Paper submitted to Department of Mechanical and Manufacturing, Faculty of
Engineering, University of Putra Malaysia, in partially fulfilment of the requirements
for the Degree of Master in Manufacturing System Engineering.
May 2006
Abstract of the project to the Department of Mechanical and Manufacturing, Faculty of
Engineering, University of Putra Malaysia in partially fulfillment of the requirement for the
Degree of Master in Manufacturing System Engineering.
Abstract:
FATIGUE ANALYSIS ON DIE INSERT OF CONNECTING ROD IN
CLOSED DIE FORGING PROCESS
By
MOHD AMRI SULAIMAN
Supervisor: Prof. Dr. Abdel Magid Salem Hamouda
Faculty: Engineering
To meet the increasing demand for more accurate forged products with a higher added value
and of higher material yield, precision forging-related technology has been making
remarkable progress.
In this
regard,
research
and development on CAD/CAM/CAE (computer-aided
design/computer-aided manufacturing/computer aided engineering) systems for practical use
have been vigorously promoted. CAD/CAM/CAE technology has already established itself
in the fields of designing and manufacturing sheet metal dies and is extensively used in the
aircraft and automobile industries. The CAD/CAM/CAE system developed and operated for
the hot forging of connecting rod.
In conventional hot forging of connecting rods, the material wasted to the flash accounts
approximately 20-40% of the original workpiece. In order to reduce the cost of forged
products, the forging must be performed in a closed cavity to obtain near-net or net shape
parts. In flash less forging, the volume distribution of the preform must be accurately
controlled to avoid overloading the dies and to fill the cavity. Additionally, the preform
must be simple enough to be mass-produced.
This work used the CAD/CAM/CAE system for fatigue analysis on die insert of connecting
rod in closed die forging process. The implementation of this study consists of five stages; i)
modelling part (connecting rod) using CAD software (Solidworks 2005), ii) preliminary die
insert design, iii) stress-strain simulation of die insert, iv) die insert fatigue analysis and
lifetime, and v) developed CNC code programming for die insert. In the first stage,
Solidworks 2005 software was used for modeling part (connecting rod). The second stage,
again CAD software (Solidworks 2005) was used to model the primary design of the die
insert based on the shape of the forged part. In third stage, simulated the die inserts of
connecting rod and analysed the maximum stress-strain applied on the die insert and the
requirement of load to perform the forging operation. Meanwhile in fourth stage,
determination fatigue analysis and lifetime on die insert was done by comparing the values
from S-N curve and maximum stress-strain value from FEA result. In the last stage,
Unigraphics software was used to develop CNC machining code or known GM code for
fabricating the die inserts.
11
Abstrak projek yang dikemukakan kepada Jabatan Mekanikal dan Pembuatan, Fakulti
Kejuruteraan, Universiti Putra Malaysia sebagai memenuhi sebahagian dari keperluan untuk
Ijazah Sarjana Kejuruteraan Sistem Pembuatan.
Abstrak:
ANALISIS KELEMAHAN TERHADAP SELITAN ACUAN ROD
PENYAMBUNG DALAM PROSES TEMPA ACUAN TERTUTUP
Oleh
MOHD AMRI SULAIMAN
Penyelia: Prof. Dr. Abdel Magid Salem Hamouda
Fakulti: Kejuruteraan
Bagi memenuhi peningkatan terhadap permintaan kepada barang tempa yang lebih jitu dan
berkualiti tinggi, proses teknologi berkaitan kejituan tempaan telah begitu menonjol.
Sehubungan dengan itu, pembangunan dan penyelidikan sistem CAD/CAM/CAE untuk
tujuan praktikal amat digalakkan. Teknologi CAD/CAM/CAE telah lama diwujudkan
terutamanya dalam rekabentuk dan pembuatan acuan kepingan logam dan ia digunakan
secara meluas di
dalam
indusri pembuatan kapal
terbang
dan
kereta.
Sistem
CAD/CAM/CAB ini juga telah dilaksanakan dan diguna pakai dalam pembikinan rod
penyambung.
lll
Di dalam proses penempaan panas rod penyambung secara normal, pembaziran bahan
logam sering berlaku kira-kira 20 - 40 peratus daripada bahan logam asal. Oleh itu, untuk
mengurangkan kos produk tempaan, proses tempaan mesti dilakukan pada acuan tertutup
untuk mendapatkan bentuk yang seakan hampir dari bentuk asal. Di dalam proses tempaan
kurang lebihan bahan, jumlah pengaliran logam mestilah dikawal dengan tepat bagi
mengelakkan lebihan bebanan kepada acuan. Secara ringkasnya, prabentuk hendaklah sesuai
untuk pengeluaran secara besar-besaran.
Kajian ini melibatkan penggunaan sistem CAD/CAM/CAE untuk menganalisis kelemahan
selitan acuan rod penyambung dalam proses tempa acuan tertutup. Perlaksanaan kajian ini
terdiri daripada lima peringkat; i) merekabentuk rod penyambung menggunakan program
CAD, (Solidworks 2005), ii) persediaan utama merekabentuk selitan acuan, iii) Simulasi
ketegangan selitan acuan, iv) menentukan jangka hayat dan analisis kelemahan selitan
acuan, dan v) membangunkan kod program CNC untuk selitan acuan. Pada peringkat
pertama, program Solidworks 2005 digunakan untuk merekabentuk rod penyambung. Pada
peringkat kedua, sekali lagi program Solidworks 2005 digunakan untuk merekabentuk
selitan acuan berdasarkan bentuk rod penyambung. Bagi peringkat ketiga pula, simulasi
selitan acuan rod penyambung dan analisis ketegangan maksimum terhadap selitan acuan
serta bebanan yang diperlukan untuk proses tempaan ini. Seterusnya peringkat ke empat,
menentukan jangka hayat dan analisis kekuatan-kelemahan selitan acuan dengan membuat
perbandingan nilai dari graf S-N dan keputusan dari ' finite element analisis' (FEA). Pada
peringkat terakhir pula, program Unigraphics digunakan untuk membangunkan kod
pemesinan CNC atau dikenali GM-code untuk fabrikasi selitan acuan.
lV
ACKNOWLEDGEMENT
First of all I would like to appreciate to the Kolej Universiti Teknikal Kebangsaan Malaysia,
KUTKM as an employer and gave approval to me for furthering my Master study. Also
thanks to the Jabatan Perkhidmatan Awam, JPA as sponsorship in this study.
Many industry person and academicians from various sources have contributed generously
to the completion of this case study. I greatly acknowledge my supervisor Prof. Dr. A.
Magid Hamouda, lecturer in the Department of Mechanical and Manufacturing Engineering
for his trust, sharing ideas and supportive effort all these while. I would also like to take this
opportunity to thank my examiner, Assoc. Prof. Dr. Wong Shaw Voon for his effort and
guidance in correcting this case study.
I would like to thanks my family, who always has been with me supporting me even in the
hardest of time, my dear friends whom have been very helpful and encouraging.
This case study is the combination of computer aided design (CAD) for modeling purpose,
computer of manufacturing (CAM) for G-code program and fabrication purpose and
computer aided engineering (CAE) for finite element analysis purpose. For this I would also
like to thank the individual stated below for their time to share information and ideas.
Mr. Amir Radzi
Engineer Researcher,
National CADCAM, Sirim Berhad.
Mr. Jefridi Mat Siman
Engineer Researcher,
Machinery and Tooling Technology Program, Sirim Berhad.
v
Mr. Goh Kok Ming
Production Engineer,
Metal Techs Sdn. Bhd,
Ayer Keroh, Melaka.
Mr. Jaafar Lazim
Senior Technician,
Faculty of Manufacturing,
Kolej Universiti Teknikal Kebangsaan Malaysia.
vi
APPROVAL
This project submitted to the Department of Mechanical and Manufacturing, Faculty of
Engineering, University of Putra Malaysia has been accepted as a partial fulfillment of the
requirements for the Degree of Master of Manufacturing System. The members of the
examinations committee are as below;
fA
Ｍﾷ Ｍ ｾＭ
Ｍ
(;2
Supervisor, PhD
Prof. Dr. A. Magid Hamouda
Department of Mechanical and Manufacturing,
Faculty of Engineering,
University of Putra Malaysia
Examiner, PhD
Assoc. Prof. Dr. Wong Shaw Voon
Department of Mechanical and Manufacturing,
Faculty of Engineering,
University of Putra Malaysia
vii
DECLARATION
I hereby declare that the project paper is based on my original work except for quotations
and citations that have been duly acknowledge. I also declare that it has not been previously
or concurrently submitted for any other degree of university or other institutions.
MOHD AMRI BIN SULAIMAN
viii
List of Contents
Page
ABSTRACT
ABSTRAK
111
ACKNOWLEDGEMENTS
v
APPROVAL SHEETS
Vll
DECLARATION FORM
V111
LIST OF CONTENTS
IX
LIST OF FIGURES
X111
LIST OF TABLES
xv
CHAPTER
1
2
INTRODUCTION
Forging for connecting rod
2
Objective
4
Scope of studies
5
Project organizations
5
LITERATURE REVIEW
7
Forging
7
Comparison forging with other processes
8
Why are forging so prevalent
15
Closed die forging
19
Requirements for closed die forging
20
Case Study Flashless Forged Connecting Rod
21
ix
3
4
Process details Closed-die forging
24
Process requirements
27
Open die forging
29
Hot forging
30
Die life service
30
Die service life based on plastic deformation
31
A brief history of the Finite Element Method
32
The history ofMSC.NASTRAN
33
The overview ofMSC.NASTRAN
35
Connecting Rod in the engine block
37
Basic steps in the finite element method
39
METHODOLOGY
40
Stage I: Modelling part using CAD software (Solidworks 2005)
41
Stage 2: Preliminary die insert design
42
Stage 3: Stress-strain simulation of die inserts
43
Stage 4: Die inserts fatigue analysis and lifetime
43
Stage 5: Developed CNC code for the die inserts
43
COMPUTER AIDED DESIGN-CAD: Modeling Die Insert
44
Computer Aided Design, (CAD)
44
Solidworks 2005 software for modelling
44
Die insert drawing and dimensions
46
Material properties for die insert
48
Connecting rod drawings, dimensions and material
50
Billet dimensions
52
x
5
6
COMPUTER AIDED ENGINEERING-CAE: Finite Element
Analysis on Die Inserts of Closed Die Forging
54
Computer Aided Engineering, (CAE)
54
MSC.NASTRAN software
55
Die Inserts analysis
56
Mesh Element
56
Pressure Load
57
Stress-Strain
58
Displacement on Die Inserts
59
Constraint Force on Die Inserts
59
S-N Curve for Carbon Steels (AISI 1055)
61
Fatigue Analysis of Die Inserts
62
Comparison values between Finite Element Analysis and S-N curve
63
COMPUTER AIDED MANUFACTURING-CAM: Die Insert of
Closed Die Forging
65
Computer Aided Manufacturing, (CAM)
65
Overview Unigraphics software
65
Tool Path
67
Cavity Mill
69
GM code
71
XI
7
8
RESULTS AND DISCUSSIONS
72
Determination Fatigue Analysis of Die Insert
72
Billet Dimensions
75
CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE WORK
The Conclusions of Project
76
Project Contribution
78
System Limitations
78
Recommendations for Future Work
79
REFERENCES
80
APPENDICES
Appendix 1: In Part of CNC code for the Machining Operation
Required to Produce the Die Insert
82
Appendix 2: A diskette that contain Full CNC code for Die Insert
92
Fabrication
BIODATA OF AUTHORS
93
Xll
List of Figures
Page
Figure
1. Connecting rod
2
2. Closed die forging with and without flash
3
3. Closed die forging
19
4. Comparison between conventional forging and closed die forging
21
5. Closed die forged connecting rod
22
6. Stages in forging a connecting rod
23
7. A heated blank between 2 halves of a die
24
8. Compressive stroke squeezes the blank into the die
24
9. Part ejected using an ejector pin
25
10. Waste material (flash)
25
11. Connecting rod location in the engine block
38
12. Forging industry
38
13. Industrial - Closed Die Forging
38
14. Flowchart of the methodology
41
15. Connecting rod
42
16. Die insert
43
17. Cavity dimensions (in mm)
46
18. Cavity depth for Lower Die Insert (in mm)
46
19. Lower Die Insert dimensions (in mm)
47
20. Cavity depth for Upper Die Insert (in mm)
47
21. Upper Die Insert dimensions (in mm)
47
22. The Upper die insert and lower die insert at open position
48
Xlll
23. Product (connecting rod) dimensions (in mm)
50
24. Billet dimensions with offset 2% (in mm)
53
25. Mesh element on die insert
56
26. Pressure load applied on the cavity profile
57
27. Stress-strain
58
28. Displacement on the die insert (in mm)
59
29. Constraints force on die inserts
60
30. Constraints force on bottom die inserts
60
3 1. S-N curve for carbon steel (AISI 105 5)
61
32. S-N curve show comparison between O"max and O"se
64
33. The Create Operation
67
34. Tool paths for first cavity milling
68
35. Cavity Mill part
69
36. Cavity Mill Parameters Setting
70
37. S-N curve show comparison between
O"max
and O"se
74
38. Stress-strain values (in N/m 2) for carbon steel AISI 1055 die insert
74
39. The thickness of billet (in mm)
75
XIV
List of Tables
Table
Page
I. Comparison between forging and welding/fabrication
9
2. Comparison between forging and casting
IO
3. Comparison between forging and powder metallurgy
11
4. Comparison between forging and reinforced plastic and composites
12
5. Comparison between forging and machined steel bar/plate
13
6. Advantages of forging compare to other process
14
7. Specifications of the Closed die forged connecting rod
23
8. AISI 1055
49
9. Composition of AISI I 055
49
I 0. Mechanical properties of AISI 1055
49
xv
Chapter 1
Introduction
1.1 Introduction
If the weight of a connecting rod (see Fig. 1) can be reduced while increasing its strength,
an automobile's fuel efficiency will be improved. Currently, steel connecting rods are used
in passenger cars. However, some manufacturers have attempted to use alternative lighter
materials. Recently, various composite materials based on aluminum have been considered,
but not yet successfully adopted, for automotive engines. The main reasons are that these
materials are not strong enough, or when strong enough, are too expensive.
Flash less forging offers the possibility of producing aluminum composite connecting rods
at competitive costs. The design of flash less forging processes is more complex than the
design of conventional closed die forging with flash. Therefore, in order to accelerate the
development of the manufacturing process as well as to reduce the development costs, a new
design method must be developed and applied. The finite element method (FEM) offers the
possibility to design the entire manufacturing process on a computer. This leads to a
reduction of the cost and time in process and tool design, tool manufacturing, and die tryout. In addition, it is possible to modify the process conditions in the simulation to find the
best manufacturing conditions for a product.
1
Figure 1: Connecting rod
1.2 Forging for connecting rod;
In the forging of connecting rods, three main methods are employed. The first method
consists of making a rough pre-form from a non-porous billet and hitting it several times in
a press until the final shape is obtained (Figure 2a). This method results in 20-40% of the
material to be wasted as flash. A major advantage of the closed-die forging with flash is that
the volume of the pre-form can vary within a wider range than for flash less forging. This
makes it easier to continuously manufacture products with the same quality (3].
However, a trimming process is necessary to remove the existing flash . The second method
is net shape flash less forging (Figure 2b). During this process the pre-form is totally
enclosed in the die cavity so that no flash formation is allowed. There is no material waste
as in impression forging. However, tight volume control of the pre-form is necessary to
insure filling of the cavity and to avoid overloading the tooling. The third method, which is
widely used, is hot forging of powder metallurgy pre-forms. This method yields virtually no
material waste and produces near-net shape products. However, the metal powder is '
expensive compared to conventional materials.
2
In principle, forging operations are non-steady state processes, in which the deformation of
the material takes place under three-dimensional stress and strain conditions. The material
flow depends mainly on the following;
I. geometry of the cavity;
2. geometry of the flash opening;
3. initial and intermediate billet geometry;
4. percentage of flash ;
5. heat transfer between the tooling and the billet;
Forging
Flash less
Forging
ｷｩｾｨ＠
Flash
Forging with
Flash
ｆｬ ｡ｳ
ｆｯ
ｲ ｾＱｧ＠
ｨｬ ･ｳｾ＠
I
I
I
Lower
Die
I
· Lower
Punch
Sta rt of Stroke
End of Stroke
(b)
(a)
Figure 2: Closed die forging with and without flash
Thus, the requirements to perform a successful flashless forging process are:
I. The volume of the initial pre-form and the volume of the cavity at the end of the ,
process must be the same.
2. There must be neither a local volume excess nor a shortage, which means that the
mass distribution and positioning of the pre-form must be very exact.
3. If there is a compensation space in the dies, the real cavity must be filled first.
3
1.3 Objective of the study
Currently most finite element codes that simulate billet-forming processes consider only
plane-strain or axisymmetric deformations. Since many industrial parts such as connecting
rods have very complex geometries, the metal flow is three-dimensional and cannot be
properly modeled with a two-dimensional approximation. This means that a three
dimensional simulation of the manufacturing process must be performed to get adequate
results.
For this study, it is focusing on simulation non-steady process using a finite element method
(MSC.NASTRAN) in order to better understanding of structural and fatigue analysis on the
closed die forging. The main product to study is connecting rod that most using in
automotive industry. Besides, the goals of the study are;
);;>
To develop a finite element model of die insert for connecting rod in closeddie forging process.
);;>
To determine fatigue strength material analysis and cycle lifetime of die
insert.
);;>
To developed the CNC code for the die insert using Unigraphics software.
4
1.4 Scope of study
There are many finite element analysis techniques on closed die forging, for the
development of this project, it only concentrated on fatigue strength material analysis of the
die insert design using the MSC.NASTRAN software. Meanwhile the Solidworks 2005 and
Unigraphic software will be used for modeling and CAM purpose. Currently there have
some stages of connecting rod manufacture such as blank, edging, blocking and finishing
but in this project, it only highlighted on the final stage (finishing).
1.5 Project organization
This project consists of eight chapters:
Chapter 1: Introduction of forging for connecting rod, objective and scope of this study.
Chapter 2: Reviews on the literature from journal, books and internet. The area covered
including types of forging, requirements of closed die forging, process detail of closed die
forging, material forged, die life service, history of finite element analysis, history of
NASTRAN software and basic steps in the finite element analysis.
Chapter 3: Describe methodology in this study to do the modeling, simulation, analysis and
developed CNC code.
Chapter 4: Modeling the connecting rod and die insert by using CAD software, Solidworks
2005.
5
Chapter 5: Finite Element Analysis on Die Inserts of Closed Die Forging, by using finite
element software, MSC.NASTRAN.
Chapter 6: Developed CNC machining program or known as GM code for die insert
fabrication purpose.
Chapter 7: Results on of the project and discussions.
Chapter 8: Conclusion of the project and recommendations for future works.
6
Chapter 2
Literature review
2.1 Forging
Forging is defined as the process in which metal is plastically deformed with application of
temperature and pressure. It is used to change not only the shape but also the properties of
the metal because it refines the grain size and therefore improves its structure [2]. Forging is
a cost-effective way to produce net-shape or near-net-shape components. Forged parts are
used in high performance, high strength and high reliability applications where tension,
stress, load and the human safety are critical considerations. They are also employed in a
wide range of demanding environments, including highly corrosive and extreme
temperatures and pressures.
Various parameters such as complexity of the part, friction between dies and workpiece,
type of press, die and workpiece temperature, material of workpiece governs the forging
process. Forging process is said to be successful if die cavity is completely filled and stress
in the workpiece is less than ultimate stress corresponding to the workpiece material, with
minimum force .
Forging is the controlled deformation of metal into a specific shape by compressive forces.
In year 8000 B.C. forging process are evolved from the manual art of simple blacksmithing.
Then a series of compressive hammer blows performs the shaping or forging of the part.
Now, modem forging uses machine driven impact hammers or processes, which deform the
workpiece by controlled pressure [1].
7
The forging process is superior to casting in that the parts formed have denser
microstructures, more defined grains patterns, and less porosity, making such parts much
stronger than casting. All metals and alloys are forgeable, but each will have a forgeability
rating from high to low or poor.
The factors involved are the material's composition, crystal structure and mechanical
properties all considered within a temperature range. The wider the temperature range, the
higher the forgeability rating. Most forging is done on heated workpieces. Cold forging can
occur at room temperatures. The most forgeable materials are aluminum, copper, and
magnesium. Lower ratings are applied to the various steels, nickel, and titanium alloys. Hot
forging temperatures range from 93°C (200°F) to 1650°C (3000°F) for refractory metals [6].
2.2 Comparison forging with other processes
There are some processes in forming and shaping part such as forging, casting, welded or
fabrication, machined steel bar, powder metallurgy, reinforced plastics and composites. All
of these processes have their own characteristics, advantages and disadvantages. Here
comparison some characteristics such as strength of the part (grain oriented), cost effective,
material savings, design flexibility, simplified production, and part inspections, between
forging and other process are made. Below Table 1-6 have shown this comparison.
8