Casting is a process by which a hot, liquefied material, for example, molten metal, is poured into a designed mould cavity and allowed to cool and harden. When it cools, it takes the form of the mould cavity. The hardened result is removed from the mould and undergoes a finishing process, which may involve polishing, welding, carving, filing, grinding, colouring, etc.
What Is Bronze Casting?
Bronze casting is when the molten metal used is bronze. Bronze is an alloy that consists mostly of copper and tin. Aluminium, nickel, zinc, manganese, phosphorus, arsenic and silicon can also be present. Depending on your needs, you can either have aluminium bronze, nickel bronze, zinc bronze, copper bronze, etc.
What Are the Applications of Bronze Casting?
Bronze casting is mainly used for sculptural art. For industrial applications, it depends on the composition of bronze. For example, aluminium bronze can be used for machine tools and bearings because it is hard and resistant to wear and tear. Phosphor bronze can be used for electrical contacts or musical instruments.
Bronze Casting Processes
Bronze casting can be achieved through lost-wax casting (investment casting) and sand casting.
Lost-waxing casting starts with the creation of a clay model or pattern. The clay can either be oil or water-based. A mould is then made from the pattern using a flexible gel or plaster. It is peeled off, and hot wax is poured into the mould. The wax has to capture all the details. It creates a hollow casting, and after it cools, it is removed from the mould.
Wax rods/sprues are attached to the hollow casting to provide a channel for bronze. The wax is then dipped in silica ceramic, and after it dries, it is put in a kiln where the wax melts and leaves the mould hollow. Molten bronze is then poured into the mould, and after it cools, the ceramic mould is chipped off. The bronze sculpture can then undergo the finishing process.
Sand casting is when sand is used to make a specially designed mould cavity. Molten bronze is then poured into the sand mould cavity, and when it cools, it forms the desired pattern/shape/object, which then undergoes finishing.
The choice between lost-wax casting and sand casting is dependent on the kind of product you want. Lost-wax casting is used when you want products requiring precision. Such products have complex designs. Sand casting is used for simple designs. It is also cheaper than lost-wax casting.