Metal casting
Metal casting is the process of filling a mold with a liquid metal (making a workpiece or product from liquid metal by filling it with a cavity of a given shape and size with subsequent hardening).
In the most common sense, metal casting is a typical process for obtaining products, which consists in filling a special container (mold) that forms the surface or part of the surface of the manufactured product with liquid metal with a further thermo-temporary transition of the liquid material to a solid state of aggregation and obtaining, as a result, a solid billet close in configuration, size and properties to the final product.
Metal castings are also called foundry products obtained by metal casting process.
The essence of metal casting processes and foundry goals
Metal casting (or foundry) is a production method used to shape castings by pouring molten metal into a previously prepared casting mold, and the mold cavity has the design of the final product. After metal solidification and cooling in the mold, a casting-blank of the part is obtained.
The main objective of the foundry is the manufacture of metal castings that having a diverse design with the maximum approximation of their shape and dimensions to the shape and dimensions of the finished part (when metal casting method it is impossible to obtain a casting whose shape and dimensions exactly correspond to the shape and dimensions of the part).
Metal casting is classified to:
- Casting material:
ferrous metals (cast iron and steel alloys) and non-ferrous metals (non-ferrous and precious metals – copper, aluminum, magnesium, tin, bismuth, lead, silver, gold) and alloys.
non-metallic – from plastics, polymers, minerals, concrete, gypsum, organic substances, ceramics, glass, salt, slag and other materials. - Purpose of castings: industrial, technical, domestic, medical, decorative, artistic, etc.
- Dimensional accuracy, degree of surface roughness, machining allowance: rough, accurate, precision.
- Special requirements for castings.
- Technology (type, method) of castings production: Expendable mold casting is a generic classification that includes sand, plastic, shell, plaster, and investment (lost-wax technique) moldings. This method of mold casting involves the use of temporary, non-reusable molds. Non-expendable mold casting differs from expendable processes in that the mold need not be reformed after each production cycle. This technique includes at least four different methods: permanent, die, centrifugal, and continuous casting. This form of casting also results in improved repeatability in parts produced.