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Metal Casting ,its types and methods
1) Casting is a manufacturing process that involves pouring molten material into a mold and allowing it to solidify. The mold can be either permanent or temporary. 2) There are two main types of casting based on the mold: expendable mold casting, which uses sand casting; and non-expendable mold casting, which includes die casting and centrifugal casting. 3) Sand casting uses various types of sand as the mold material and is performed using either the green sand or air set method. Over 70% of metal castings are produced via sand casting.
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Overview of Casting workshop in Mechanical Engineering at NUST Pakistan.
Topics to be discussed include definition, types, processes, defects, and allowances in casting.
An introduction to casting techniques and processes.
Casting is a manufacturing process using molds to shape molten material, categorized by mold type.
Different casting methods: Expendable (Sand, Plaster, Investment) and Non-expendable (Die, Centrifugal).
Focus on sand casting, the most common method, which makes up 70% of all metal castings.
Explains the sand casting method, materials used, and specific techniques like green and air set.
Visual representation of the sand casting process.
Description of mold parts: cope and drag, including the core used for internal features.
Key terms related to sand casting techniques and their purposes.
Introduction to non-expendable casting techniques like die and centrifugal casting.
Details of die casting which uses reusable molds and injection molding techniques.
Visual representation of the die casting method.
Centrifugal casting explained, detailing how molten metal solidifies under centrifugal force.
Visual representation showcasing the centrifugal casting process.
Introduction to investment casting with visual aids.
Multiple visual representations demonstrating various stages of the investment casting process.
Introduction to casting allowances necessary to account for material shrinkage during solidification.
Examples of shrinkage allowances for different materials used in casting.
Illustration and explanation of 'draft' used for mold retrieval.
Introduction to common defects found in castings such as blow holes and cold shuts.Repetitive detailed descriptions of various casting defects including blow, cold shuts, and misrun.
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Metal Casting ,its types and methods
- 1. Casting Workshop Technology Department ofMechanical Engineering College of E&ME, NUST Pakistan
- 2. Contents • Definition ofCasting • Types of Casting • Sand Casting & Associated Terminologies • Permanent Mold Casting • Die Casting • Casting Allowances • Casting Defects
- 3. CASTING & ITSTYPES
- 4. Casting • A manufacturingprocess that involves pouring molten material into a mold and then allowing it to cool and solidify. • Mold contains a hollow cavity of the desired part shape and can be either permanent or temporary. • After solidification, the part is ejected or broken out of the mold. The solidified part is also called “casting.” • Casting is mainly categorized into two types, based on nature of mold. Other sub-categorizes are based on mold material, pattern type and molten material injection process.
- 6. Types of Casting Casting Expendable MoldCasting Permanent Pattern Casting Sand Casting Plaster Mold Casting Temporary Pattern Casting Evaporative Casting Investment Casting Non-expendable Mold Casting Die Casting Centrifugal Casting Pressure Casting
- 7. SAND CASTING EXPANDABLE MOLDCASTING
- 8. Sand Casting • Sandcasting is a metal casting process that uses various types of sand as the mold material. Over 70% of all metal casting are produced via sand casting. • The sand mold is enclosed is a box frame called flask and is held together by a bonding agent. • Sand Casting is performed by either: – Green Sand Method – Or Air Set Method
- 10. Sand Casting -Illustrated
- 11. Sand Casting Mold Thetop and bottom halves of the sand casting mold known as cope and drag respectively. The wooden items are the core used to create hollow internal features. Cope Drag Core
- 12. Sand Casting Terminologies Core CHECKCORE & ITS PURPOSE IN CASTING.
- 13. DIE AND CENTRIFUGALCASTING Non-expendable Mold Castings
- 14. Die Casting • Itis part of an array of casting processes known as injection molding. • The process is characterized by forcing molten metal under pressure into a mold. • The mold cavity is created by the assembly of two steel halves which are machined to produce desired cavity shape. • Unlike sand casting, the mold is reusable in die casting. Die casting is used for mass producing high-accuracy and good finished parts.
- 15. Die Casting -Illustrated
- 16. Centrifugal Casting • Inthis casting process, a permanent mold is rapidly spun around its axis (300-3000 rpm) while molten metal is being poured into it. • The molten metal is thrown outwards along the mold walls under centrifugal force, where it solidifies to form cylinders. • Centrifugal castings can be generated in all lengths and diameters and thickness. The process is used to create semi-finished castings which are subsequently machined.
- 17. Centrifugal Casting -Illustrated
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- 30. Casting Allowances • Sincedimensional changes occur when a material solidifies, appropriate allowance is introduced into the pattern. • To prevent shrinkage of casting, the pattern is over sized based on a set of so called “shrink rules”. • For example aluminum has a solidification shrinkage of ~6.6 % and low carbon steel has a shrinkage of ~2.5-3.0 %. • Apart from shrinkage allowance, a draft is introduced into the pattern as well. The draft is a slight taper in the pattern that allows for easy retrieval of the pattern from the mold.
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- 32. Casting Defects • Blow:A relatively large cavity produced by gases that prevent the molten metal from filling the mould completely. • Cold Shuts: A defect produced when two fronts of molten metal do not fuse properly therefore creating an area of weak strength. • Misrun: Is created when the molten metal does not completely fill the mould either due to high viscosity or absence of a riser. • Inclusion: Contamination of the casting by external materials such as slag or chips broken off from the ladle.
- 33. Casting Defects • Blow:A relatively large cavity produced by gases that prevent the molten metal from filling the mold completely.
- 34. Casting Defects • ColdShuts: A defect produced when two fronts of molten metal do not fuse properly therefore creating an area of weak strength.
- 35. Casting Defects • Misrun:Is created when the molten metal does not completely fill the mould either due to high viscosity or absence of a riser.
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