The theory of casting forming, liquid metal forming is often called casting, casting technology has a long history. As early as 5000 years ago, our ancestors were able to cast copper and bronze products. Casting is a widely used liquid metal forming process. It is a method that liquid metal is poured into the mold cavity and cooled and solidified to obtain a certain shape of blank or parts. Liquid molding parts account for a large proportion in machinery and equipment. In machine tools, internal combustion engines, mining machinery and heavy machinery, liquid parts account for 70% ~ 90% of the total weight, 50% ~ 70% in automobiles and tractors, and 40% ~ 70% in agricultural machinery. The liquid forming process has been widely used because it has the following advantages:



1. It can be used to manufacture blank with complex shape and inner cavity. Such as various box, machine bed, cylinder block, cylinder head, etc.



2. The process is flexible and adaptable. The size of liquid forming parts is almost unlimited, its weight can be from several grams to hundreds of tons, and its wall thickness can be from 0.5mm to 1m. In industry, any metal material that can be dissolved into liquid can be used for liquid molding. For cast iron with poor plasticity, liquid forming is a method to produce its blank or parts.



3. The cost of liquid forming parts is low. Liquid molding can directly use waste machine parts and chips, and the equipment cost is low. At the same time, the machining allowance of liquid forming parts is small and the metal is saved. However, the liquid metal forming process is too many and difficult to control, which makes the casting quality not stable. Compared with the forgings of the same material, due to the loose structure and coarse grains in the liquid forming process, the internal defects such as shrinkage cavity, shrinkage porosity and porosity are easy to occur. Its mechanical properties are low. In addition, the labor intensity is large and the conditions are poor. It has excellent mechanical and physical properties. It can have a variety of comprehensive properties of different strength, hardness and toughness, and also has one or more special properties, such as wear resistance, high temperature and low temperature resistance, corrosion resistance, etc. The weight and size range of casting is very wide. The light weight is only a few grams, the weight can reach 400 tons, the wall thickness is only 0.5 mm, the thickness can be more than 1 meter, and the length can be from several millimeters to more than ten meters, which can meet the requirements of different industrial departments.