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11.3.1 Describe lost wax casting.
An ancient casting form that is still widely used today, used in sculpture, dentistry and jewellery. It is where a replica is made from the artists original by way of a mould produced using wax and plaster of paris.
11.3.2 Describe how lost wax cast products are made.
Consider preparation of the master pattern; injection of wax to create copy; creation of a wax tree to make a wide range of small parts from the same metal; covering wax with ceramic or plaster of Paris; removal of wax; and the addition of the final chosen material.
A nice flash animation from James Peniston Sculture
11.3.3 Explain how a range of products are made using lost wax casting.
Jewellery, dental implants, hip replacements and wind instrument keys.
11.3.4 Describe high-pressure die casting.
Die casting is mainly used for low-melting alloys. Molten metal is forced into a mould under high pressure.
11.3.5 Describe how high-pressure die cast products are made.
Draw a diagram to include holding furnace, injector, gooseneck and die.
11.3.6 Explain how a range of products are made using high-pressure die casting.
Consider hip replacements, disk drive chassis and carburettors.
Hip replacements, disk drive chassis and carburettors all require a great amount of dimensional accuracy or in the case of disk drive chassis and carburettors thin walls can be produced accurately and without machining.
The process ...
11.3.7 Outline two advantages and two disadvantages of high-pressure die casting.
Advantages: high accuracy, good surface finish, thin walls, and high rate of production.
Disadvantages: high plant costs, high tooling costs, cannot be used for a wide range of alloys, and limitations on maximum size that can be cast.
Bulleted list and italicised paragraphs are excerpted from Design Technology: guide. Cardiff Wales, UK: International Baccalaureate Organization, 2007.
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