Lecture-05 - LearnEASY

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ENMAT101A Engineering Materials and Processes
Associate Degree of Applied Engineering
(Renewable Energy Technologies)
Lecture 5 – Casting Process
Casting iron in
a sand mould:
Wikipedia
www.highered.tafensw.edu.au
TAFE NSW -Technical and Further Education Commission
Casting
Reference Text
Section
Higgins RA & Bolton, 2010. Materials for Engineers and Technicians,
5th ed, Butterworth Heinemann
Ch 5
This lecture follows exactly with Higgins Chapter 5.
EMMAT101A Engineering Materials and Processes
TAFE NSW -Technical and Further Education Commission
Ingot casting (Higgins 5.2)
Cooling a thick casting causes poor grain
structure. Large ingots are a problem.
Grains in cast
aluminium
www.spaceflight.esa.int
EMMAT101A Engineering Materials and Processes
TAFE NSW -Technical and Further Education Commission
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 671.252/META
Recommended Viewing: All sections.
5.6 Investment-casting
5.7 Full-mould process (Lost foam)
EMMAT101A Engineering Materials and Processes
TAFE NSW -Technical and Further Education Commission
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.
http://openlearn.open.ac.uk
EMMAT101A Engineering Materials and Processes
TAFE NSW -Technical and Further Education Commission
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 671.253/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
TAFE NSW -Technical and Further Education Commission
(Higgins: 5.9 The choice of casting process)
In order of precision:
In order of melting point:
1. Investment-casting
2. Die-casting
3. Sand-casting
4. Full-mould process
1. Investment-casting
2. Sand-casting
3. Die-casting
EMMAT101A Engineering Materials and Processes
TAFE NSW -Technical and Further Education Commission
Metal Casting Processes
Wikipedia: Casting
EMMAT101A Engineering Materials and Processes
TAFE NSW -Technical and Further Education Commission
(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 sandcasting (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 diecasting becomes less than the cost
per sand-casting.
Higgins Fig 5.8
EMMAT101A Engineering Materials and Processes
TAFE NSW -Technical and Further Education Commission
Shrinkage Allowance
Grey cast iron
Contraction
(%)
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
1.8
Zinc
2.5
Manganese steel
2.6
Metal
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.
Based on;
http://www.calculatoredge.com
EMMAT101A Engineering Materials and Processes
TAFE NSW -Technical and Further Education Commission
Design Study
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
http://openlearn.open.ac.uk/mod/oucontent/view.php?id=399740&section=2.1
EMMAT101A Engineering Materials and Processes
TAFE NSW -Technical and Further Education Commission
Online Properties Resources.
Graphical comparison of materials properties.
DoITPoMS: Dissemination of IT for the Promotion of Materials Science
Wikipedia: Casting
Metal Grains and processing
EMMAT101A Engineering Materials and Processes
TAFE NSW -Technical and Further Education Commission
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
TAFE NSW -Technical and Further Education Commission
QUESTIONS
Moodle XML: Some questions in 10107 Processing
1. Define all the glossary terms.
2. List 2 advantages that casting offers over other manufacturing processes.
3. 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.
4. 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.
5. Explain the following casting terms: Flash, porosity, feeder, runner, draft,
ejectors, cores.
EMMAT101A Engineering Materials and Processes
TAFE NSW -Technical and Further Education Commission

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