Type heat treatment: In order to improve or change the original structure of castings, eliminate internal stress, ensure the properties of castings and prevent the deformation and damage of castings, some castings need heat treatment after cleaning. The heat treatment of castings generally includes quenching, annealing, normalizing, as-cast quenching and tempering, artificial aging (see aging treatment), stress relief, softening and graphitization. For example, high manganese steel castings require high wear resistance and sufficient toughness, and its internal structure should be austenite. Therefore, it is necessary to quench the casting, that is, after the casting is heated to the austenite region to make it completely austenitic, it is quickly quenched with water and chilled, so that the austenite cannot be transformed and maintained. This process is also called water toughening treatment or solution treatment. Plastic surgery: it is divided into three aspects: correction, repair and surface finishing. Some castings are deformed during solidification, cooling and heat treatment, which makes some dimensions out of tolerance and needs to be corrected. Calibration is mainly carried out by mechanical force at room temperature or warm state. When the deformation is too large, the high temperature correction can also be carried out in the heating furnace by using the self-weight or external pressure of the casting. The external defects of castings are mainly repaired by welding. The leakage defects of castings that require air tightness and liquid tightness are solved by pressing in the plugging agent. The rough and uneven surface of castings is generally polished and trimmed by hanging grinding wheel and high-speed grinding wheel. Rough machining: Before casting leaves the factory, rough machining should be carried out locally according to technical conditions. After rough machining of castings, defects can be found and solved in time, weight can be reduced, and waste and chips can be classified and reused on the spot. Rust prevention treatment: Some castings and machine tool castings need rust prevention treatment before leaving the factory to prevent rust during transportation and storage. Generally, the primer is applied after the final inspection is qualified.