Primary forming processes

Most metals, with the exception of some precious ones, are found in the form of minerals or ores. The ores are smelted to convert them into metals e.g. iron is obtained from iron ore (haematite), aluminium from bauxite and copper from copper pyrites. 

Aluminium is extracted from bauxite by an electrolytic process. Commercially pure aluminium is soft and weak and it is alloyed to improve the mechanical properties. Aluminium alloys are available wrought or cast, in sections convenient for subsequent working by rolling, drawing, casting or extrusion. 

Copper is extracted from copper pyrites and is refined by remelting, in a furnace or electrolyticaUy. Copper is alloyed to produce a range of brasses and bronzes. These materials may then be roUed, drawn, cast or extruded. 

Where the metal has to be remelted, as in the case of casting, it is usual to supply it to the foundry in the form of notched ingots or bars of relatively small cross-section. These can be broken into smaller pieces for ease of handling and loading into small furnaces. 

Where the metal is to be subjected to further forming processes - e.g. rolling, extrusion, drawing or forging - it would be wasteful to remelt, both from an energy viewpoint and from the effect the remelting would 

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The two most important primary forming processes, injection molding and extrusion, are described below in somewhat greater detail. 

Integration of processing steps in primary forming processes (inmold assembly of structural components)... 

Primary forming processes High toolingAow labor cost High Medium to low Low... 

Name five properties required of raw materials which make then suitable for primary forming processes. 

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