Modern casting is a manufacturing process used especially to cast intricate shapes and figurines by using sand as the moulding material. The sand is held in a metal box and molten metal is poured carefully into the mould. Once the metal has cooled, the mould is broken away and the finished part is removed. The mould is usually discarded, although some may be reused. Modern casting has a number of advantages over more traditional methods of manufacturing, including the ability to produce complex shapes and the reduced amount of labor and raw materials needed to produce them.
Modern casting can be seen as a subset of the work conducted under the umbrella of metal casting. Specifically metal sand casting, also referred to as green sand casting, is a metal casting process in which moulds are made from moist sand mixed with a binding agent such as clay. This type of casting is arguably the most popular metal casting process owing to the relatively low cost of the process and the number of industrial applications that it finds.
Although green sand casting is widely used, there are a number of other methods used for modern casting. The types of casting and their main applications are summarised below.
Investment Casting
Investment casting, sometimes referred to as lost wax casting, is a process whereby a wax pattern of a desired product is produced and then surrounded by a layered shell of high-temperature ceramic. This module is heated until the wax is burned out, leaving a hollow space in the module perfect for molten metal to be poured-in. This method is particularly suited where extremely accurate parts are required and can be used to create complex shapes. Common applications include cast surgical implants, kitchen appliances and car components.
Centrifugal Casting
Centrifugal casting is the process of pouring molten metal into a rotating mould. As the mould spins, the centrifugal force pushes the molten metal against the walls of the mould and ensures a uniform wall thickness. This process is mainly used for producing pipes, tubes, fireplaces and fittings as it allows for faster casting times and improved dimensional accuracy.
Permanent Mould Casting
Permanent mould casting involves pouring molten metal into a reusable mould made of metal, ceramic, graphite or other material instead of using a one-off sand mould. Metal parts that are too complex to be made using sand casting can usually be produced using permanent mould casting. Consequently, this method is primarily used to produce more intricate automobile parts, structural components, artwork and figurines.
Die Casting
Die casting is one of the most versatile casting processes and is typically used for producing a number of parts with high precision. This method involves injecting molten metal under high pressure into a steel die and mould which restricts the molten material to the desired form. As this process yields much stronger and denser parts, it is primarily used for manufacturing automotive components, household fittings and furniture.
Vacuum Casting
Vacuum casting is a unique casting process for producing accurate parts and components quickly. This method typically involves pumping a layer of special resin into a mould and allowing it to harden. The solidified resin is then placed in a pressurized chamber and molten metal is poured over it. The sudden drop in pressure removes the excess metal and leaves behind the desired parts. Vacuum casting is particularly suited to producing smaller complex parts using a variety of metals.
Conclusion
Modern casting is a sophisticated process that today is used to manufacture a number of everyday items. The range of casting processes and the variety of materials used means that this method is also often used to produce some of the most advanced and intricate components. The five methods discussed above each have their own particular advantage, with some better suited to producing large volume parts whereas others are excellent for creating highly precise components.
