High Integrity Aluminum Die Casting

A critical step in the overall aluminum die casting process journey to producing a high integrity product is the preparation of the molten metal. A wealth of knowledge has been gained in recent years and has been compiled in this single comprehensive text, making it an absolute must for those serious about maximizing and controlling metal quality. Detailed technical information is presented to provide the reader with a thorough understanding of the key parameters that impact metal quality.

The book consists of eight chapters. The initial chapter describes the die casting process variants including high vacuum, semi-solid and squeeze casting. Next, a description of aluminum die casting alloy designations, effects of alloying elements, applications, properties and property predictions is presented. Then metal melting, transferring and holding is meticulously addressed. Furnace types and maintenance, refractories, and heat transfer aids are also described.

Pertinent to the achievement and control of high quality metal, the following topical areas are covered in-depth: sludge formation and prediction methods; dross formation and minimization methods; hydrogen gas, inclusions and their formation mechanisms; melt cleaning systems and techniques; and, quality assurance methods including metal assessment techniques and non-destructive evaluation of cast parts.

The preparation of this book includes contributions from engineers, scientists, and academicians with expertise in metal casting.

 

TABLE OF CONTENTS
Preface                                                         
1      High Integrity Die Casting Process Variations                                                                                       iii
1.1  Introduction

1
1.2  Conventional Die Casting 1
1.3  High Integrity Die Casting

3
1.4  High Vacuum Die Casting

4
1.5  Squeeze Casting

5
1.6  Semi Solid Metal (SSM) Processing

6
References

14
2      Aluminum Die Casting Alloys
2.1 Alloy Designations

15
2.2 Effects of Alloying Elements

17
2.3 General Applications of Alloy Families

27
2.4 Die Casting Alloy Properties

30
2.5 Aluminum Alloy Property Predictability

35
References

37
3      Melting, Transferring and Holding
3.1 Melting & Heat Transfer

39
3.2 Melting Process Concerns

40
3.3 Melting Furnaces

43
     3.3.1  Crucible (Pot)

43
     3.3.2  Reverberatory

44
     3.3.3  Stack Melter

45
     3.3.4  Isothermal (ITM)

46
3.4 Furnace Maintenance 47
3.5 Refractories

47
3.6 Heat Transfer Aids

48
3.7 Metal Transfer & Holding

50
References

52
4      Sludge Formation & Prediction Methods
4.1 Sludge Formation Equation

53
4.2 Experiment to Verify Sludge Equation

55
4.3 Morphology and Hardness of the Sludge Particles

56
4.4 Effect of Chemistry on Sludge Formation

57
4.5 Effect of Cooling Rate on Sludge Formation

59
4.6 Effect of Holding Temperature on Sludge Formation

60
References

62
5       Dross Formation & Minimization Methods
5.1 Dross Formation

63
5.2 Influence of Melter Type on Dross Generation

65
5.3 Influence of Charge Materials on Melt Loss

66
5.4 Influence of Operating Practices on Melt Loss

66
5.5 Dross Generation During Turbulent Transfers

68
6      Melt Related Quality Detractors
6.1 Introduction

69
6.2 Hydrogen Gas

70
6.3 Solid Particle Inclusions

73
6.4 Inclusion Formation Mechanisms

76
6.5 Inclusion Appearance and Morphology

88
References

93
7      Melt Cleaning Systems and Techniques
7.1 Introduction

95
7.2 Removal of Unwanted Phases by Flotation and Fluxing

96
7.3 Removal of Unwanted Phases by Filtration

111
7.4 Removal of Unwanted Phases by Electromagnetic Separation

118
References

119
6      Melt Related Quality Detractors
8.1  Introduction

121
8.2  Metal Cleanliness Assessment Techniques

122
8.3  Non-Destructive Testing of Cast Parts

131
References

135