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Lost-wax casting – also called investment casting, precision casting, or cire perdue (French: [siʁ pɛʁdy]; borrowed from French) [1] – is the process by which a duplicate sculpture (often a metal, such as silver, gold, brass, or bronze) is cast from an original sculpture. Intricate works can be achieved by this method.
Investment casting was invented in 4500–4000 BC in Southeast Asia [1] and carbon dating has established mining at Alderley Edge in Cheshire, UK, at 2280 to 1890 BC. [6] Ötzi the Iceman, a male dated from 3300 to 3200 BC, was found with an axe with a copper head 99.7% pure; high levels of arsenic in his hair suggest his involvement in copper ...
One key in casting metal cores is to make sure they do not contain any porosity as it will induce flaws into the molded part. In order to minimize porosity the metal may be gravity cast or the molding cavity may be pressurized. Another system slowly rocks the casting dies as the molding cavity fills to "shake" the air bubbles out. [9]
A casting defect is an undesired irregularity in a metal casting process. Some defects can be tolerated while others can be repaired, otherwise they must be eliminated. They are broken down into five main categories: gas porosity, shrinkage defects, mould material defects, pouring metal defects, and metallurgical defects.
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The fragile wax patterns must withstand forces encountered during the mould making. Much of the wax used in investment casting can be reclaimed and reused. [2] Lost-foam casting is a modern form of investment casting that eliminates certain steps in the process.
For technique 1, a wax pattern is designed on the die from the cast impressions and for technique 2 the wax is packed into the tooth preparation in the mouth and adapted the shape of the cavity. [28] Inlay wax is chosen due to its brittleness – it breaks upon removal from undercut of a cavity, either on the die or in the mouth.
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