Among all kinds of casting methods, sand casting is the most common one. This is because it has many advantages: the mechanical parts with complex inner cavity and shape can be obtained by sand casting; it is applicable to both ferrous and non-ferrous metals; the casting process equipment is simple and the cost is low; the metal consumption can be accurately mastered in the production process, so it can be controlled and guaranteed that the metal will not be wasted in the design stage; due to the influence of metallurgical characteristics, Some metals and alloys can only be produced by casting but not by other methods; castings are almost unlimited in weight and size, and some castings weigh up to 200t. Although sand casting is widely used in foundry production, the dimensional accuracy, surface finish and internal quality of castings produced by this method are far from meeting the requirements of many mechanical parts, especially some aerospace products such as blades, vanes, nozzles and other heat-resistant alloy parts in jet engines, These parts not only require high dimensional accuracy and surface finish, but also can not be manufactured by other methods. In order to meet these requirements, the foundry workers have invented many new casting methods, which are different from the ordinary sand casting, collectively known as special casting method, namely special casting.
Compared with common sand casting, special casting has two basic characteristics: (1) change the manufacturing process or material of the mold. (2) Improve liquid metal filling mold and subsequent condensation conditions. For each special casting method, it may only have one aspect of characteristics, or it may have two aspects of characteristics at the same time.
Common special casting methods include investment casting, metal casting, EPC, pressure casting, gypsum casting, ceramic casting, low pressure casting, vacuum suction casting, squeeze casting, centrifugal casting, continuous casting, semi continuous casting, shell casting, graphite casting, electroslag casting, etc.