The anti-corrosion ability and appearance of Dalian cast iron castings after blackening treatment depend on the quality of post-treatment. Due to their loose structure, cast iron castings must be fully rinsed after blackening to release the acid residue in the pores, so as to avoid the erosion of blackening film in the future and make the workpiece yellow. Due to the great development of the global die casting industry, the demand for aluminum alloy die castings in other industries is also increasing. Changshu Jinling hardware products factory has a one-stop professional production line of aluminum die casting, stamping, gold processing and spraying, with advanced technologies such as professional production, mold opening and design. The factory has rich production capacity and huge output. The mb2610 (three scales) and bm311 (four scales) produced not only meet domestic demand, but also sell well in Canada, the United States, Eastern and Western Europe, Southeast Asia and other countries and regions. With the rapid development of the global casting industry, the demand of various enterprises for a variety of castings is also increasing. Especially in recent years, many automobile manufacturers have replaced gray iron castings with castings, so the demand for castings is increasing.