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This oblong piece of aluminium was produced by injecting molten aluminium metal into a steel mould in a process called die casting. Once cooled, the solid cast aluminium is removed by dismantling the mould, which can then be re-used. The thin lip on one of the edges of the shape is a ‘flash’, which forms when aluminium leaks into the thin join between mould pieces.
Mould design is critically important in die casting. The narrow circular protrusion on one of the edges is likely from the ‘runner’, the section through which molten metal enters the die. The rough texture left by machining on some of the faces of this object suggest that this piece may be waste material from a larger aluminium casting, cut off from the desired casting. Its blackened surfaces may be from oil or graphite used as lubricant to help free the cast piece from its mould.
The casting of molten metal into moulds is a process with ancient roots – some of the oldest examples are copper castings dating back around 6000 years. The process was used to make tools, weapons, relics and coins. Over the following millennia, different casting processes were developed, such as sand casting – where the mould is made from sand – and the lost wax process, where the desired object is first made out of wax, and then coated with ceramic and fired to melt the wax out to create the negative space mould inside. To remove the cast metal object, these moulds must be broken apart.
With die casting – the method from which this object has been discarded – the mould is designed to be broken apart systematically and reused. The metal is forced into the mould at high pressure, unlike other metal casting processes where the metal is simply poured. Die casting was developed in 1838 in order to produce the intricate and precise metal pieces needed for moveable type in the printing industry. Today, die casting is used to produce all sorts of everyday objects, such as locks, gears, toys, door handles, mechanical components, gadget housings and golf clubs.
Sample ID: 146
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