Fundamentals of Die Casting Design

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Fundamentals of Die Casting Design

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Preface This book, Fundamental of Die Casting Design, describes the fundamental of design of the die casting process and die mold/runner. It is intended for people who have at least some knowledge of the basics of fundamental science, such as calculus, physics etc. This book will benefit the die casting engineer (the project and process engineers) as well as managers and anyone else who deals with the die casting operations will find this information useful.

The structure of this book is such that many of the chapters should be usable independently. For example, if you need information about, say, pQ 2 diagram, you can read just chapter 7. I hope this makes the book easier to use as a reference manual. However, this manuscript is first and foremost a text book, and secondly a reference manual only as a lucky coincidence.

I have tried to describe why the theories are the way they are, rather than just listing "seven easy steps" for each task. This means a lot of information is presented which is not necessary for everyone. These explanations have been marked as such and can be skipped. 1 Reading everything will, naturally, increase your understanding of the fundamentals of die casting design.

CONTENTS

I BASIC SCIENCE 1
1 Introduction 3
1.1 The importance of reducing production costs 4
1.2 Designed/Undesigned Scrap/Cost 5
1.3 Linking the Production Cost to the Product Design 6
1.4 Historical Background 6
1.5 Numerical Simulations 8
1.6 "Integral" Models 11
1.7 Conclusion 1
2 2 Basic Fluid Mechanics 13
2.1 Introduction 13
2.2 What is fluid? Shear streass 14
2.2.1 Thermodynamics and mechanics concepts 14 Thermodynamics 14
2.2.2 Control Volume, c.v 15
2.2.3 Energy Equation 16
2.2.4 Momentum Equaton 16
2.2.5 Compressible flow 16
3 Dimensional Analysis 17
3.1 Introduction 20
3.2 The processes in die casting 21
3.2.1 Filling the shot sleeve 21
3.2.2 Shot sleeve 22
3.2.3 Runner system 24 3.2.4 Die cavity 26
3.2.5 Intensification period and after 27
3.3 Special topics 28
3.3.1 Is the flow in die casting is turbulent? 28 Additional note on numerical simulation 30
3.3.2 Dissipation effect on the temperature rise 30
3.3.3 Gravity effects
31 3.4 Estimates of the time scales in die casting 31
3.4.1 Utilizing semi dimensional analysis for characteristic time 31 Miller's approach 33 Present approach 34
3.4.2 The ratios of various time scales 36
3.5 Similarity applied to Die cavity 37 3.5.1 Governing equations 37
3.5.2 Design of Experiments 40
3.6 Summary of dimensionless numbers 40 3.7 Summary 42
3.8 Questions 42
4 Fundamentals of Pipe Flow 47
4.1 Introduction 47
4.2 Universality of the loss coefficients 47
4.3 A simple flow in a straight conduit 49
4.3.1 Examples of the calculations 50
4.4 Typical Components in the Runner andVent Systems 51
4.4.1 bend 51 4.4.2 Y connection 52
4.4.3 Expansion/Contraction 52
4.5 Putting it all to Together 52
4.5.1 Series Connection 52
4.5.2 Parallel Connection 53 5 Flow in Open Channels 55
5.1 Introduction 55
5.2 Typical diagrams 58
5.3 Hydraulic Jump 58

II DIE CASTING DESIGN 59
6 Runner Design 61
6.1 Introduction 61
6.1.1 Backward Design 61
6.1.2 Connecting runner seqments 62
6.1.3 Resistance 63
7 Q 2 Diagram Calculations 67
7.1 Introduction 68
7.2 The "common" pQ 2 diagram 68
7.3 The validity of the "common" diagram 74
7.3.1 Is the "common" model valid? 74
7.3.2 Are the trends reasonable? 76 Plunger area/diameter variation 76 Gate area variation 77
7.3.3 Variations of the Gate area, A 3 78
7.4 The reformed pQ 2 diagram 79
7.4.1 The reform model 79
7.4.2 Examining the solution 81 The gate area effects 81 General conclusions from example
7.4.2 85 The die casting machine characteristic effects 86 Plunger area/diameter effects 89 Machine size effect 93 Precondition effect (wave formation) 94
7.4.3 Poor design effects 94
7.4.4 Transient effects 94 7.5 Design Process 94
7.6 The Intensification Consideration 95
7.7 Summary 96
7.8 Questions 96
8 Critical Slow Plunger Velocity 97
8.1 Introduction 98
8.2 The "common" models 98
8.2.1 Garber's model 98
8.2.2 Brevick's Model 101 The square shot sleeve 101
8.2.3 Brevick's circular model 102
8.2.4 Miller's square model 102
8.3 The validity of the "common" models 103
8.3.1 Garber's model 103
8.3.2 Brevick's models 103 square model 103 Improved Garber's model 103
8.3.3 Miller's model 103 8.3.4 EKK's model (numerical model) 104
8.4 The Reformed Model 104
8.4.1 The reformed model 104
8.4.2 Design process 106
8.5 Summary 107
8.6 Questions 107
9 Venting System Design 109
9.1 Introduction 109
9.2 The "common" models 110
9.2.1 Early (etc.) model 110 9.2.2 Miller's model Ill
9.3 General Discussion 112
9.4 The Analysis 113
9.5 Results and Discussion 115
9.6 Summary 118
9.7 Questions 118
10 Clamping Force Calculations 119
Appendixes 121 A What The Establishment's Scientists Say 123
A.l Summary of Referee positions 124
A. 2 Referee 1 (from hand written notes) 125
A.3 Referee 2 126
A.4 Referee