Precision casting is constantly developing, and precision steel castings are often a large part. Its quality level largely reflects the casting level of a country. Unfortunately, for a long time, the overall quality of my country's large and medium-sized steel castings has not improved much, and small precision castings rarely meet the requirements of true high precision. Due to the lack of competitiveness in quality and the disposal of waste sand, it has been seldom used in castings of electromechanical products in foreign countries, and is generally used in specific products. Due to the low production cost and mature technology, the carbon dioxide hardened sodium silicate technology occupies a dominant position in the production of large and medium-sized steel castings in China. However, due to the poor surface quality of castings, it is difficult to meet the requirements of export castings except for low-end products. The mechanical products made from this type of casting have rough appearance and lack competitiveness in the international market. However, in the domestic market, affected by habitual forces, a considerable number of users have no requirements for the quality of steel castings, especially its appearance quality, as long as they can meet the basic functional requirements. In this way, steel castings produced by the carbon dioxide hardened sodium silicate sand process are generally acceptable. When the product requirements are high, or for export, some steel casting plants rely on sanding to "peeling" methods to improve surface quality. The quality of large and medium-sized steel castings needs to be improved urgently.