Metal Casting
Metal casting is the use of molten metal poured into a mold to shape, cool and solidify into a desired form. This manufacturing process is one of the oldest and most efficient for the production of shaped components with the ability to produce size, shapes and parts that are impossible to create via other processes. Metal casting has a long history, being found in the art of ancient civilizations like Egypt, Greece and China. The knowledge of casting is said to originate from the Sumer people of Mesopotamia more than 4000 years ago, as they produced copper and bronze pieces in molds they formed.
Today there are numerous processes used in metal casting spanning a variety of manufacturing industries. Patterns, made of either wood or metal, are used to create the initial shape of the part, which is then reversed and used as a negative shape in the mold. This type of casting requires ample skill and experience; precision placement of gates and risers is essential to ensure molten metal fills the entire cavity and creates a full part. Placement of application-specific core boxes used in combination with the pattern helps to carve out the internal features of a desired part.
Once the mold is made the molten metal is poured into the mold and allowed to cool and solidify. After solidification the part is ejected from the mold, often through the use of an expendable sand core, If required, follow-up operations such as trimming, machining and welding can be performed to meet a customer’s exact specifications. The mold as a whole is a hollow cavity that is formed from two or more pieces. Incompressible materials such as a sand, plaster, or a thermoset plastic both create the standard form of the mold, then act as a refractory material needed to protect the mold against the heat of melted metal.
Metal casting offers numerous advantages over other production methods like forging, stamping or CNC machining. Metal casting can produce complex shapes in massive sizes with ease; they are also capable of producing smaller components with extreme precision. This process also offers one of the lowest production costs per piece, and is extremely capable of producing high volume orders with reduced setup costs and need for machining.
There are, however, limitations with metal casting and other issues to consider. Alloy usage can limit the practical application for metal casting, as some materials are either too brittle or too malleable to be poured. Cores can leave metal porosity, which can be a key concern when structural integrity is needed or when the casting is to act as a pressure chamber. Careful control of metal flow via the use of overflows and grates, chokebush’s and risers must also be carefully monitored during the casting process.
Overall metal casting has been proven over hundreds of years, making it one of the most efficient production processes available today. It is a great tool for precision engineering, and can easily and economically produce medium-to-large-volume production runs of a wide variety of shapes and sizes.
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