universiti putra malaysia computer aided design and...

UNIVERSITI PUTRA MALAYSIA

COMPUTER AIDED DESIGN AND ANALYSIS IN DIE/MOULD OF CASTING PROCESS

MD. SHAMSUL ABEDIN

FK 1997 5

COMPUTER AIDED DESIGN AND ANALYSIS IN DIEIMOULD OF CASTING PROCESS

MD. SHAMSUL ABEDIN

MASTER OF SCIENCE UNIVERSITY PUTRA MALAYSIA

1997


By

MD. SHAMSUL ABEDIN

Thesis Submitted in Partial Fulfilment of the Requirements for the Degree of Master of Science in the Faculty of Engineering,

University Putra Malaysia

September 1997

DEDICATED TO

My parents

AKNOWLEDGEMENTS

The author wishes to express his profound appreciation and gratitude to the

chairman of the supervisory committee, Dr. Shamsuddin bin Sulaiman, Head of the

Mechanical and Manufacturing Engineering Department for his supervision,

guidance and constructive suggestions and comments throughout the duration of the

project.

The author is also indebted to the members of the supervisory committee, Mr.

Mohd. Rasid Osman and Dr. A. M. S. Hamouda for their affectionate guidance,

prompt decision and valuable assistance during this period. Special gratitude to Dr.

A. M. S. Hamouda for useful suggestions and supplying valuable research materials.

Sincere thanks to Mr. Tajul Ariffin, Mr. Ahmad Saiffuddin, Mr. Suleiman, Mrs

Ruffina Rouf and Mrs. Rohana Tajul of the Engineering Faculty and the member of

the other laboratories for their technical support. A special thanks goes to my friends

and fellow colleagues for their encouragement.

Finally the author acknowledges the assistance rendered by the respective Lecturers,

Staffs of the Graduate School and Staffs of the University Putra Malaysia, too

numerous to mention individually, in many direct and indirect way.

111

TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

LIST OF FIGURES . . . . . . . . . . . . . . . . . . .. . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

LIST OF PLATES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . xi

LIST OF ABBREVIATIONS AND NOMINCLATURES . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii

ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv

ABSTRAK ............................................................................................................... xv

CHAPTER

I INTRODUCTION ..... ..... ............ . ... ... .... ..... .. . ... . . . . . . . . . ... .... .. . . . .. . .... .... 1 Project Background ...... ..... ......... .... . . ... ........... . ....... .... .... . . . . .. . . .... .. . .... . 1 Computer Involvement in Design and Analysis .. . . .. .... ..... . .. . .......... ... 2 Integration of Computer Aided Design and Computer Aided Analysis .......... .............................. ........... .. ... .... .... ............................. 3 Concept of DielMould Design in CAD . .. ........ . ........ ... ........ . .. . ....... .. . .4 Problem Definition and Scope ofWork. .... ......... ......... ........... ... ..... ... 5 Objectives of the Present Work. .......... . .......... . . . . . . . . . . . .. ... ...... ..... ... ..... 6 Layout of Thesis ... ... ...... .............. . .... .... ... .. . ... . . . ....... . .. ........... . . . . . . ... ... 7

II LITERATURE REVIEW .......... ..... . ...................... . ... .... ..... .............. 8 Computer Aided Design (CAD) . . . . ......... .... .... . ... .... . .. . ....... ........ . ....... 10 Design Specification Processing . ... .. . . ... .... ..... .. . . .... .. . . . .. ......... ... ... ...... 1 2

Find out the Axisymmetric Sequence . ........ .. . . . ....... ....... ... .. ... 1 2 Initial Geometric Modelling ........ .... . . . ... . . .... . . . . . ... ........ .. .. . . . . . . . 1 2

Geometric Modelling Schemes ....... . . . ....... ....... .. ......... ........ ... .. . . ...... .. 1 3 Wire - Frame Geometry ...... . . . . ....... . . . . ....................... ....... .. . . . 13 Surface Representation Scheme . . . .. ..... . .... ........ .. ........... ... .. . . .. 13 Solid Modelling .. .... ...... . . ........ ... . . . . ..... ............ .............. .... . ... .. 14

Mesh Generation .. ........ .... .... . ... .... ......... ....... .... . . . . . ....... .. .. . . . . ........... . .. 1 5 Creating Database . . . . .. .. . . .. . .. . . . ...... ............ ................. .... . .... ....... .......... 16

Transferring and Extracting . . ....... .............. . .. .. . ....... ... .. ............. ...... . . . . 16

IGES Format ... .... . . . ..... . . ................. ........ .... .......................... ... 17 DXF Format. .. . . . . . ..... .... ............................ ... ... ................... . .... 17

Graphical Aids for Pre-processing ... .. . ...................... ..... . . . ....... .......... 18 Computer Aided Analysis ... .. . ...................... .............. .. ... ........ ..... .... .. 19 Graphical Aids for Post-processing . .. . .. . . . . . .... ............... . .. . . ............... .. 19

Die/Mould Design Considerations ..... .. .................. ..................... . ... . . . .20

tV

Die/Mould Design ................................................................... 20 Factors of Die/Mould Failure ......... . ............................. .......... .22 Failure Due to Design ............................................................. .23 Failure Due to Poor Heat Treatment. . .................................... .23 Alignment of DielMould ...................................... .................. .24 Draft Angle Consideration ....... ................................................ 24 Runner Systems Consideration ................................. ...... ......... 25 Steps for Mechanical Surface Treatment.. ............................... 26 Thermal Stresses in Die/Mould ................................................ 26

III MATHEMATICAL MODELLING ...................................... ........... 27

Fluid Network Formulations ............................................................... .28 Matrix Representation ofthe Mod ........................................... 30 Modelling Technique for Feeding System ................... . . .......... 31

Thermal Network Formulation ............................................................. 33 Matrix Representation .............................................................. 34 Modelling Technique for Thermal Exchange System .............. 37

IV SOFTWARE DEVELOPMENT FOR CASTING PROCESS ...... 43

Mesh Generation .................................................................................. 44 Quadratic Shape ....................................................................... 44 Curved Shape .................................... ....................................... 45

Tag Generation for the Process ......................... .................................. .45 Fluid Network ..................................................................................... 45

Pre-processing Program ................ ........................................... 46 Fluid Network Program .......................................................... .46 Generation of the Data File for Graphs .... .............................. .4 7

Four Node Graphs ............. .......................................... 47 Single Node Graph ..................................................... .48

Thermal Network ........................................................................ ........ 48 Pre-processing Program ......................................................... .48 Thermal Network Program .... ................................................ .49 Generation of the Data File for Graphs ...... ..... ...................... .49

Four Node Graphs ....................... .......... . ............ . .... ... 49 Single Node Graph ........... ........ .. . . . . . . . . . . . ..................... 50

V CASTING SIMULATION RESULTS AND DISCUSSION ........ 64

Physical Properties of the Die/Mould and Filling Material . . .............. 65 Model Shape for the Analysis .............. .............................................. 65 Fluid Filling Progress for Model Shape .......... ................................... 65 Comparison between Different Draft Angles of the Runner System and Flow Rate ............. ........ . ..... .... . ..................................................... 66 Thermal Analysis ....... .............. . . . . . . .......... ........................................ ... 67

\'

Model Mesh ......................................................................................... 68 Temperature Response ........................................................ ................ 68 Temperature Contours ........ ................................................................. 69 Thermal Stresses in DielMould .................................... . . ..................... 69

VII CONCLUSIONS AND RECOMMENDATIONS ......................... 91

Conclusions ................................ ......................................................... 91 Recommendations .... ........................................................... ................ 93

REFERENCES .......................................................................................................... 94

APPENDICES ........................................................................................................... 101

VITA ........................................................................................................................... 150

PUBLICATIONS ...................................................................................................... 151

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LIST OF TABLE

Table Page

1 Physical Property for Die and Cast Materials 65

Vll

LIST OF FIGURES

Figure Page

1 Stage of Finite Element Pre-processing 19

2 Fluid Flow in a Cylindrical Volume 39

3 Laminar and Turbulent Velocity Profile 39

4 Steps of the Conceptual Design Phase 40

5 Mesh Generation Steps 40

6 3D View of the Analysed Model 41

7 2D Representation of the Model Mesh 41

8 Heat Transfer Mechanisms 42

9 The Network Diagram Representation of Homogeneous Link, Interface Link and Coolant Link 42

10 Thermal Network Diagram Schematic 42

11 Mesh Generation Process Layout 51

12 Tag Generation Process Layout 51

13 Pre-processing Program for Fluid Network 52

14 Flow Chart for Fluid Filling Process 53

15 Data Extraction Layout 54

16 Pre-processing Program for Thermal Network 55

17 Flow Chart of Thermal Network Program Process 56

18 Shows the Proposed Model for the Analysis 71

19 Liquid Metal Progress for the Flow Rate of 0.009 m3/sec 74

20 Pressure Variation at Node 1 with Time for the Flow Rate m3/sec 74

21 Metal Filling Percentage V s Time for the Flow Rates 0003 m3/sec 75

VIII

22 Number of Element Filled by the Fluid V s Time for Flow Rate of

0.003 m3/sec 75

23 Comparison of Flow Rate V s Pressure for Different Draft Angles 76

24 Comparison of Flow Rate Vs Time for Different Draft Angles 76

25 Model Mesh for the Core of Die/Mould 77

26 Temperature Curve at Interface Nodes 78

27 Temperature Curve at Cast And Mould 78

28 Temperature Curve at Different Physical Condition 79

29 Temperature Curve at Node 281 And 193 79

30 Temperature Curve at Interface Link Nodes 80

31 Temperature Distribution During the Casting Process 80

32 Temperature Distribution Contour at Time 0.0 sec 81






38 Temperature Distribution in Die from Cast Material in First Trial 84

39 Axisymmetric Temperature Contour for the Core 85

40 Shaded Contour of Thermal Stress of the Axisymmetric Core 86

41 Thermal Stress Contour with the Results 87

42 3D Wire-Frame and Solid Model of the Mesh 88

43 Shows the Temperature Change along B-A Section 89

44 Shows the Temperature Change along C-D Section 89

45 Shows the Thermal Stresses along B-A SectIOn 90

IX

46 Shows the Thermal Stresses along C-D Section 90

x

LIST OF PLATES

Plate Page

1 Opening Logo of the CasCAD 57

2 Menu Profile for the Mesh Generation 57

3 Menu Profile for the Fluid Network 58

4 Tag Generation for the Element 58

5 Menu Profile for Fluid Network 59

6 Four Nodes Graph for the Fluid Network Post-processor 59

7 Single Node Graph for the Fluid Network Post-processor 60

8 Smooth Curve for the Fluid Network Post-processor 60

9 Step Information for Thermal Network 6 1

10 Menu Profile for the Thermal Network 6 1

1 1 Mesh Generation for the Thermal Network 62

12 Four Nodes Graph for the Thermal Network Post-processor 62

13 Single Node Graph for the Thermal Network Post-processor 63

14 Smooth Curve for the Thermal Network Post-processor 63

Xl

ABBREVIATIONS AND NOMENCLATURES

CAD Computer Aided Design

CAM Computer Aided Manufacturing

CAA Computer Aided Analysis

CAE Computer Aided Engineering

FEA Finite Element Analysis

VDU Visual Display Unit

DBMS: Database Management System

IGES Initial Graphics Exchange Specification

DXF Drawing Interexchange File

AME Advanced Modelling Extension

A Cross-sectional area (m2)

Af Coolant cross-sectional area (m2)

As Structure cross-sectional area (m2)

Ai Interface area (m2)

B Heat transfer coefficient increase with time (W /m2°C)

C Specific heat (J/kgOC)

f Friction factor

g Gravitational acceleration (m/s2)

gr Gravitational force per unit volume (radial direction) (N/m3)

gz Gravitational force per unit volume (axial direction) (N/m3)

h Heat transfer coefficient (W Im2°C)

H Enthalpy (J/kg)

hi Interface heat transfer coefficient (W /m20C)

Xll

hI Head loss (m)

k Loss coefficient

K Thermal conductivity (W/mOC)

L Length (m)

LeJf Effective length (m)

Lt Latent heat (J/kg)

m Mass (kg)

P Pressure (N/m2)

Pe Inertia pressure (N/�2)

Pt : Total pressure (N/m2)

Pv : Viscous pressure (N/m2)

q : Heat flow (W)

Q : Flow rate (m3/s)

QI : Heat flow at node 1 (W)

Q2 : Heat flow at node 2 (W)

t Time(s)

T Temperature (OC)

p Density (kg/m3)

fL Viscosity (kg/ms)

r Shear stress (N/m2)

xiii

Abstract of thesis submitted to the Senate of University Putra Malaysia in partial fulfilment of the requirements for the degree of Master of Science.


By

MD. SHAMSUL ABED IN

September 1997

Chairman: Dr. Shamsuddin bin Sulaiman

Faculty: Engineering

Computer Aided Design (CAD) and Computer Aided Analysis (CAA) have

been investigated and developed since the last twenty years as standalone systems.

There is useful link between CAD and CAA in terms of data extraction from the

graphics to non-graphics format for the analysis.

Computer Aided Design and Computer Aided Analysis packages have been

developed incorporating AutoCAD for the fluid feeding progress and the thermal

behaviour during the casting process. Network analysis process has been adopted for

the current development. The Developed package includes the CAD graphics for

design, transferring graphics to non-graphics and vice versa for pre-processing and

post-processing for the Engineering Analysis.

The Developed package has been tested for the Die/Mould design for the

proposed model. Finite element packages have been used for the prediction of the

residual stresses of the Die/Mould.

XIV

Abstak tesis yang dikemukakan kepada Senet Universiti Pertanian Malaysia sebagai memenuhi keperluan untuk ijazah Master Sains.

REKABENTUK TERBANTU KOMPUTER DAN ANALISIS DALAM ACUAN PROSES PENUANGAN

Oleh

MD. SHAMSUL ABEDIN

September 1997

Pengerusi: Dr. Shams uddin sulaiman

Faculti: Kejuruteraan

Rekabentuk Terbantu Komputer, CAD (computer aided design) dan Analisis

Terbantu Komputer, CAA (computer aided analysis) telah dikaji, dan dibangunkan

sejak dua puluh tahun yang lepas sebagai sistem-sistem berasingan. Terdapat

hubungan yang rapat di antara CAD dan CAA dari segi pentukaran data dari grafik

mahupun bukan grafik untuk membuat analisis.

Pakej CAD dan CAA telah dibina menggunakan AutoCAD untuk "fluid feeding

progress" dan kelakuan haba dalam proses "Penuangan". Proses analisis rangkaian

telah digunakan untuk kajian kini. Pakej yang direka memasukkan grafik CAD

dalam rekabentuk, pertukaran dari grafik kepada bukan grafik dan sebaliknya untuk

proses-sebelum dan proses-selepas anal isis dalam kejuruteraan.

Pakej yang direka telah diuji manggunakan rekebentuk "die/mold" untuk model

yang dicadangkan. Pakej unsur terhingga digunakan untuk membuat anggaran dalam

"residual stresses" pada ·'die/mold".

>.y

CHAPTER I

INTRODUCTION

Project Background

Technical progress is very fast in the application of the computers to the

manufacturing activities. Currently it is possible to computerise all the individual

activities that make up a 'product cycle' from the demand for a product to its

production. In this production cycle, design and analysis are the first steps among the

successive steps of the cycle. So, design and analysis are the roots of the production

cycle. Computer can perform repetitive jobs and lots of computational works very

efficiently and quickly than human beings. So, jt has become very effective to

integrate computer to design and analysis processes. Computer integration in design

and documentation helps to give the outlook of the generated idea by the designer.

After visualising the design, the designer can modify his idea without too much

effort as well as it can be presented as a final design. In Computer Aided Design

(CAD), the designer can view the drafted design in different angles and sides.

For the analysis techniques such as finite difference, finite element, boundary

element, hybrid and network element, the designer can extract the co-ordinate values

and perform the computational effort by picking those co-ordinate values. This

2

possibility helps to reduce time constraint, as well as increase the accuracy of the

calculation.

Computer Involvement in Design and Analysis

CAD involves any type of design activity, which makes use of the computer

to develop, analyse or modify an engineering design. Modem CAD systems (some

time integrated with CAD/CAM systems) are based on interactive computer

graphics which denote a user-oriented system in which the computer is �mployed to

create transformation, and display data in the form of picture or symbols (McMahon

Chris and Browne Jimmie, 1993).

However, from the viewpoint of product design evaluation, the most

important design phase is the conceptual design phase and the development of CAD

systems to support work in this phase is desirable. Conceptual design phase includes

much creative work, which is combined in a complex manner that appears to be

creative/intelligent work at first glance (Arai and Kazuaki, 1992).

Computer aided engineering simplifies the creation of a database by

permitting several applications to share the information in the database. These

applications include finite difference, network approach and finite element analysis

of stresses, strains, defections, fluid flow, temperature distribution in structures and

load-bearing members and the generation. storage, and retrieval of NC data.

Computer Aided Analysis systems are also used extensively in the design of

3

integrated circuits and other electronic devices (Kalpakjian, 1995 and Tay, A-O,

1 997).

Integration of Computer Aided Design and Computer Aided Analysis

During the past recent years, industry has made a move to incorporate

scientific techniques into die/mould design. Industries like to adopt a more

systematic strategy; since the complexity of the parts to be cast has increased, the

lead times have been reduced dramatically over the last decade. Many medium size

and even small companies are now trying to incorporate computer aided design and If computer aided manufacturing techniques in their design and manufacturing

processes in an effort to reduce both the cost and time (Zhang et. aI, 1996).

A computer aided analysis (CAA) system can be used to generate the initial

process sequence (Altan, 1985), as well as increase the accuracy of the process. The

basic calculations for generating each section in the sequence require the

computation of areas and volumes for complex parts. Designers currently perform

these computations manually while making approximation of certain sections of the

part to simplify the problem. Thus, the conventional approach to Die/Mould design

usually does not lead to very accurate results. Consequently, a reliable and practical

engineering design technique would be useful. With the aid of Finite Element

Method based analysis programs, the metal filling and heat transfer process can be

simulated to identify and eliminate potential trouble spots in the process sequence.

4

Concept of DielMould Design in CAD

Die-casting is one of the most economical casting processes for

manufacturing precision shaped parts in mass production. Die-cast component are

being used increasingly in the automobile, aerospace, electronic and other industries

because of their premium quality, low cost, and low weight (Allsop D. F. and

Kennedy D., 1983).

The die casting industry is being challenged by the world marketplace to

improve its manufacturing process continuously. To become more competitive, die

casters have to reduce development time and improve quality. CAD/CAE

technology has become an efficient tool for die casters to meet these increasingly

(Zhang et. aI, 1997).

From the general concept of the mould/die operation, it is important to

design a mould/die that will safely absorb the forces of clamping, injection, and

ejection. Furthermore, the flow conditions of the plastic path must be adequately

proportional in order to obtain uniformity of product quality cycle after cycle.

Finally, effective heat absorption from the molten metal by the Die/Mould has to be

incorporated for a controlled rate of solidification prior to removal from the moulds

(Peter. 1996).

5

Problem Definition and Scope of Work

Design, analysis and visualisation of the component are the most significant

for the product design cycle. Design, design modification and documentation needs

lot of time and intensive human labour. Commonly used analysis software needs to

create data file for pre-processing. Visualisation process shows the data progress and

outline of the generated results. Still there is not too much work on casting process

to fulfil the above mentioned phases. Computer application of those phases

eliminates tedious repetitive work and it is possible to generate almost accurate

results depending on the complexity of the pr?duct.

CAD has become a standard tool in engineering design and analysis of

manufacturing processes. At the design stage, it is normal way to develop a draught

and carry out Finite Element Analysis (FEA) to assess the pressure in different

stages of the element during the filling process and the temperature gradient in

different segments depending on the initial metal temperature according to the

feeding progress of engineering components.

Currently, many software packages are used during the phases of the design

and development processes. Most of these tools are stand-alone analysis or test

modules that are optimised to perform specific functions.

The main objective of this project is to develop a CADICAA system, which

is an integration of CAD and CAA techniques for the casting process. It will mean,

that a casting component can be drawn on a Visual Display Unit (VDU) screen and

6

the graphics data are then transferred from graphics to non-graphic format. These

data known as pre-processing data will be arranged through the programming effort

to run the Network Element programs for the fluid filling process and thermal

behaviour of casting.

Objectives of the Present Work

The present study is focused on the Computer Aided Design and Computer Aided

Analysis of DielMould of casting process, in this respect objectives of the current

project are:

1. To find a way to create model drawings for Casting pattern and DielMould

towards the direction of the integration of CAD and CAE.

2. To generate the meshes for the finite element analysis pre-processing input data

and transfer the co-ordinate data from graphics to non-graphics format which

will store all the information in a standard database for geometric calculation.

3. Analysis of the primary design is carried out using network approach for filling,

solidification and temperature distribution in Mould/Die.

4. To draw graphs and contour for the post processing data for the prediction of the

metal flow and thermal behaviour during the casting process.

5. Compare the simulated resu.1t for heat transfer by using different software

currently available for the analysis.

7

Layout of Thesis

This thesis consists of seven chapters. The first chapter contains the

introduction and aims of the research. Chapter II deals with the literature review,

which includes topics, related to Computer Aided Design and Computer Aided

Analysis and die/mould design.

Chapter III addresses the mathematical formulation of the network analysis

of fluid fl<?w and thermal aspects. Chapter IV caters for the development of the

software for the pre and post processor.

In chapter V, results are shown for the model for fulfilling the objectives.

Chapter VI concludes the overall development system and results and

recommendations for future work.

CHAPTER II

LITERATURE REVIEW

In this chapter, important factors that are involved with data extraction,

transfer, modelling and relevant works are reviewed for the integration of Computer

Aided Design (CAD) and Computer Aided Analysis (CAA). In the area of

Computer Application in Casting process, some work has been carried out on

customising CAD, but very few work has been done related to metal filling,

solidification and heat transfer process.

Recently, Zhang et. aI, 1997 developed a CAD package for Die casting by

customising CAD tools. The authors presented the P - Q2 technique which is based

on the pumping rate capacity of die casting machine which can be used to predict the

occurrence when a die is put on the machine. The authors showed the different

pumping rates influencing the runner and gating system and predicted their location

to achieve correct pressure and the flow rate.

Xinghong Li et. aI, 1995 developed some tools on computer aided design

system. They produced a multi view drawing showing isometric view in addition to

the three principal views, all properly positioned, aligned and rendered for user

interaction, and automated the production of the multi view drawing of a given solid.

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