Engineering Materials and Processes Lecture 5 Casting Process

Engineering Materials and Processes Lecture 5 – Casting Process Casting iron in a sand mould: Wikipedia

Casting Reference Text Section Higgins RA & Bolton, 2010. Materials for Engineers and Technicians, 5 th ed, Butterworth Heinemann Ch 5 This lecture follows exactly with Higgins Chapter 5. Engineering Materials and Processes

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 Engineering Materials and Processes

Low Pressure Metal Casting (Higgins 5. 3 Sand-casting) VIDEO Metal casting: Sand Moulds Scutt, Don. [Chadstone, Vic. ] : Double D Technical Productions, c 2004. 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) Engineering Materials and Processes

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 Engineering Materials and Processes

High Pressure Metal Die Casting (Higgins: 5. 4 Die-casting) VIDEO Metal casting: Die Casting Scutt, Don. [Chadstone, Vic. ] : Double D Technical Productions, c 2004. 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 Engineering Materials and Processes

(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 Engineering Materials and Processes

Metal Casting Processes Wikipedia: Casting Engineering Materials and Processes

(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 Engineering Materials and Processes

Shrinkage Allowance 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. 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 Based on; http: //www. calculatoredge. com Engineering Materials and Processes

Design Study Learning Space > All Units > Engineering and Technology > T 173_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 Engineering Materials and Processes

Online Properties Resources. Graphical comparison of materials properties. Do. ITPo. MS: Dissemination of IT for the Promotion of Materials Science Wikipedia: Casting Metal Grains and processing 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 Castings Glossary Engineering Materials and Processes

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. Engineering Materials and Processes