Iron mold sand coated casting is a technology developed in the late 1970s in China’s foundry industry. This process is a casting process in which a thin layer of coated sand is coated on the inner wall of the mold cavity of the iron mold to form a mold. The process has the characteristics of both metal mold casting and shell mold casting. Different mold wall thickness matching (iron mold thickness and sand coating thickness) can meet the different requirements of solidification and cooling for castings with different wall thickness and different materials. Due to the small amount of sand used in the casting process, the workshop generally does not need to arrange a sand treatment department. This can not only reduce equipment investment, but also significantly improve the working environment in the foundry workshop, so that China’s foundry industry can quickly realize modern production.
Compared with ordinary sand casting, metal mold backing has good thermal conductivity and fast thermal speed. During solidification, the undercooling of the casting is large, the microstructure is more compact, and the mechanical properties are improved. At the same time, due to the good rigidity of the mold, the expansion of the mold wall is limited, the internal quality and dimensional accuracy of the casting are also improved, and even the internal shrinkage cavity and porosity defects of the casting can be eliminated with the help of graphite expansion early in solidification. The process can obtain more stable casting quality and size, save metal and reduce the amount of cutting; Easy to realize mechanization and automation, high productivity, suitable for mass production.
Compared with metal mold casting, the cooling speed of iron mold sand coating process is slower, which overcomes the process defects such as white structure; The requirements for the size and surface quality of the metal mold are reduced; The service life of the metal mold is improved because the sand coating plays a certain role in protecting the metallicity; Suitable for mass production or small batch production; This technology greatly improves the quality of castings, significantly reduces waste products and has good economic benefits.