1. ENMAT101A Engineering Materials and Processes Associate Degree of Applied Engineering (Renewable Energy Technologies) Lecture 5 – Casting Process
Prescribed Text:
Ref 1: Higgins RA & Bolton, Materials for Engineers and Technicians, 5th edition, Butterworth Heinemann. ISBN:
Readings:
Callister: Callister, W. Jr. and Rethwisch, D., 2010, Materials Science and Engineering: An Introduction, 8th Edition, Wiley, New York. ISBN
Ashby 1: Ashby, M. & Jones, D., 2011, Engineering Materials 1: An Introduction to Properties, Applications and Design, 4th edition, Butterworth-Heinemann, Oxford UK. IBSN:
Ashby 2: Ashby, M. & Jones, D., 2011, Engineering Materials 2: An Introduction to Microstructures and Processing, 4th edition, Butterworth-Heinemann, Oxford UK. IBSN:
Lecture (2 hrs):
Ref 1, Ch 1: Engineering materials;
Ref 1 Ch 2: Properties of materials.
Laboratory 1 (2 hrs): Hardness test
Callister: Ch 1, 2, 18-21
Ashby 1: Ch 1, 2
Ashby 2: Ch 1
Casting iron in a sand mould:
Wikipedia 1

2. This lecture follows exactly with Higgins Chapter 5.
Casting
Reference Text
Section
Higgins RA & Bolton, Materials for Engineers and Technicians, 5th ed, Butterworth Heinemann
Ch 5
This lecture follows exactly with Higgins Chapter 5.
EMMAT101A Engineering Materials and Processes

3. Ingot casting (Higgins 5.2)
Cooling a thick casting causes poor grain structure. Large ingots are a problem.
Grains in cast aluminium
EMMAT101A Engineering Materials and Processes 3

4. Low Pressure Metal Casting
(Higgins 5.3 Sand-casting)
VIDEO
Metal casting: Sand Moulds
Scutt, Don. [Chadstone, Vic.] : Double D Technical Productions, c2004. DVD (29 min.)
This program covers jobbing moulding, cold box moulding, pit moulding, rapid prototyping, investment casting, medium volume green sand moulding, automated cold box moulding, hot box moulding, high volume lost foam moulding, hunter process, disamatic.
Mt Druitt College Library: DVD /META
Recommended Viewing: All sections.
5.6 Investment-casting
5.7 Full-mould process (Lost foam)
EMMAT101A Engineering Materials and Processes 4

5. Porosity in Low Pressure
Porosity occurs because the casting shrinks on solidification.
High pressure can fix this, but it makes the mould very expensive.
Another way is to use a reservoir of molten metal that feeds more liquid as it solidifies.
In this low pressure casting, aluminium alloy was poured down the runner into the mould. The hollow in the top of the runner caused by liquid flowing from the runner into the mould as the casting solidified. As well as the hollow at the top, you can see some holes in the runner and one hole within the casting itself. The runners and risers will later be cut off and discarded.
EMMAT101A Engineering Materials and Processes 5

6. High Pressure Metal Die Casting
(Higgins: 5.4 Die-casting)
VIDEO
Metal casting: Die Casting
Scutt, Don. [Chadstone, Vic.] : Double D Technical Productions, c2004. DVD (29 min.)
This video shows six casting processes and outlines the advantages, limitations and areas of application of each process. Included are gravity casting high pressure hot chamber die casting, high pressure cold chamber die casting and squeeze casting.
Mt Druitt College Library: DVD /META
Recommended Viewing: All sections.
5.4.1 Pressure die-casting
5.4.2 Gravity die-casting
5.5 Centrifugal casting
EMMAT101A Engineering Materials and Processes 6

7. (Higgins: 5.9 The choice of casting process)
In order of precision:
1. Investment-casting
2. Die-casting
3. Sand-casting
4. Full-mould process
In order of melting point:
1. Investment-casting
2. Sand-casting
3. Die-casting
EMMAT101A Engineering Materials and Processes 7

8. Metal Casting Processes
Wikipedia: Casting
EMMAT101A Engineering Materials and Processes 8

9. (Higgins: 5.9 The choice of casting process)
The initial costs of mould and equipment are higher in the case of die-casting (B) than for sand-casting (A). Labour costs are higher for sand casting.
The break-even value, i.e. the number of castings which must be made before the use of die-casting is justified, may be of the order of several thousands.
Once the break-even value has been reached, the cost per die-casting becomes less than the cost per sand-casting.
Higgins Fig 5.8
EMMAT101A Engineering Materials and Processes 9

10. Shrinkage Allowance
Metal
Contraction (%)
Grey cast iron
0.7 to 1.05
White cast iron
2.1
Malleable iron
1.5
Steel
2.0
Brass
1.4
Alluminium
1.8
Aluminium alloys
1.3 to 1.6
Bronze
1.05 to 2.1
Magnesium
Zinc
2.5
Manganese steel
2.6
Atoms in a solid fit closer together than in a liquid, so shrinkage occurs.
A few substances expand when they solidify because they have a very loose packing arrangement. E.g. Water (ice), and Silicon.
Higgins RA & Bolton, Materials for Engineers and Technicians, 5th edition, Butterworth Heinemann. Ch 4
Based on;
EMMAT101A Engineering Materials and Processes 10

11. Design Study 2 Casting 2.1 Introduction
Learning Space > All Units > Engineering and Technology > T173_2
> Manufacturing > PART 2. Casting:
2 Casting
2.1 Introduction
2.2 Properties for processing – casting
2.3 Types of casting
2.3.1 Permanent pattern
2.3.2 Permanent mould
2.3.3 Expendable mould and pattern
2.4 Casting processes
2.5 Casting metals
2.6 Casting plastics
2.7 Casting microstructure and defects
2.8 Casting our gearwheel
Higgins RA & Bolton, Materials for Engineers and Technicians, 5th edition, Butterworth Heinemann. Ch 4
EMMAT101A Engineering Materials and Processes 11

12. Online Properties Resources.
Graphical comparison of materials properties.
DoITPoMS: Dissemination of IT for the Promotion of Materials Science
Wikipedia: Casting
Metal Grains and processing
h ttp://
S how this website on screen. Will be using this later.
EMMAT101A Engineering Materials and Processes 12

13. EMMAT101A Engineering Materials and Processes
GLOSSARY
Binders
Break Even
Charge
Cope
Core
Draft
Drag
Feeder
Fettling
Flash
Gas Porosity
Gate
Green Sand
Impurity
Inclusion
Investment Casting
Ladle
Lost Foam
Parting Line
Pattern
Riser
Sand Casting
Shrinkage
Shrink Hole
Sink Marks
Slag
Sprue
Vacuum Casting
Castings Glossary
EMMAT101A Engineering Materials and Processes 13

14. Define all the glossary terms.
QUESTIONS
Moodle XML: Some questions in Processing
Define all the glossary terms.
List 2 advantages that casting offers over other manufacturing processes.
List in a table the advantages/disadvantages of casting processes: Sand, investment, gravity die and high pressure die. Include melting point, accuracy, setup costs, production costs, design limitations.
Sand casting pattern and sand mould costs $1900 and each part costs $50 in labour. Die casting mould (die) costs $25000 and per part is $10. Calculate the break-even quantity where die-casting becomes cheaper than sand casting.
Explain the following casting terms: Flash, porosity, feeder, runner, draft, ejectors, cores.
EMMAT101A Engineering Materials and Processes 14