Investment casting is commonly used in precision casting, also known as wax loss casting: select appropriate investment casting materials (such as paraffin) to make investment molds; Repeat the steps of dipping refractory coating and spraying refractory sand on the investment mold, hardening the shell and drying; Then melt the internal investment mold to obtain the cavity; Bake the mold shell to obtain sufficient strength and burn off the residual investment mold material,; Metal materials required for pouring; Solidification cooling and sand cleaning after shelling, so as to obtain high-precision finished products. Heat treatment, cold working and surface treatment shall be carried out according to the needs of the product.
Mass production factories should create conditions and adopt technologically advanced modeling and core making methods. The productivity of the old shock or shock molding machine production line is not high enough, the labor intensity of workers is high, and the noise is high. It does not meet the requirements of mass production, so it should be transformed step by step. For small castings, the production line of non box high-pressure molding machine with horizontal parting or vertical parting can be used. The production efficiency of solid molding is high and the floor area is small; For medium parts, various box high-pressure molding machine production lines and air impact molding lines can be selected to meet the requirements of fast and high-precision molding production lines. Core making methods can be high-efficiency core making methods such as cold core box, hot core box and shell core.
Resin self hardening sand molding and core making can be considered for medium batch large castings.
Manual molding is still an important method for heavy castings produced in single piece and small batch. Manual molding can meet various complex requirements and is more flexible without requiring a lot of process equipment. Water glass sand mold, VRH water glass sand mold, organic ester water glass self hardening sand mold, clay dry mold, resin self hardening sand mold and cement sand mold can be used; For the heavy castings produced by single piece, the pit molding method has the advantages of low cost and fast production. Multi box modeling and split box modeling are more suitable for finalized products produced in batch or long-term production. Although the investment in molds and sand boxes is high, it can be compensated from saving modeling hours and improving product quality.
Low pressure casting, die casting, centrifugal casting and other casting methods are only suitable for mass production because of the high price of equipment and molds.
