Thursday 8 October 2009

Metals

Metals are arranged into two groups:

Ferrous metals- metals that contain iron and carbon. These metals will rust. (oxegenize)
Non ferrous metals- Metals that do not contain iron. These metals do not rust.

Ferrous metals:

Mild steel: Quite string and cheap but rusts easily and can't be hardened or tempered.

High carbon steel: Harder than mild steel and can be hardened.

Cast iron: Hard however brittle under impact.

Non ferrous metals:

Aluminium: Lightweight and corosion resistant. Exspensive and not nearly as strong as steel.

Brass- quite strong, corosion resistant maileable, ductile and looks good.

Copper- Relatively soft malleable and ductile and a very good conductor of electricity.

Most metals come from ores.

Steel: Mixture of iron and carbon.

Carbon: Comes from organic materials such as coal and diamonds.

Metal processes:

Sand casting: The process involves pouring molten metal into a prepared cavity in a sand mould and allowing it to solidify, steel and aluminium are the most common metals cast.

Gravity die casting: Mazak an alloy of Zinc and aluminium is first melted in a crucible furnace. Molten metal is then poured by ladle onto a open steel mould where it is allowed to cool and soloidify. The mould is then turned upside down and topped with a hammer to release the finished casting. Gravity die casting required minimal finishing and waste is minimal because excess metal can simply be melted down and used again.

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