Metal mold casting related knowledge

Metal mold casting is also called hard mold casting. It is a casting method in which liquid metal is poured into metal molds to obtain castings. The mold is made of metal and can be used repeatedly (hundreds to thousands of times).

Comparison of metal to casting and sand casting: There are many advantages in technology and economy.

1. The mechanical properties of metal castings are higher than sand castings. For the same alloy, its tensile strength can be increased by about 25% on average, yield strength by about 20% on average, and its corrosion resistance and hardness have also been significantly improved; 2. The precision and surface finish of castings are higher than that of sand castings, and the quality and dimensions are stable. ; 3. The process yield of castings is high, and the consumption of liquid metal is reduced, generally saving 15-30%; 4. Without sand or using less sand, generally 80-100% of molding materials can be saved.

In addition, the production efficiency of metal mold casting is high; the reasons for casting defects are reduced; the process is simple, and it is easy to realize mechanization and automation. Although metal mold casting has many advantages, it also has disadvantages. Such as: 1. The manufacturing cost of metal molds is high; 2. The metal molds are air-tight and have no retreat, which may easily cause defects such as insufficient washing, cracking or daylighting of cast irons; 3. When metal molds are cast, the working temperature of the molds, The pouring temperature and pouring speed of the alloy, the residence time of the casting in the mold, and the coating used are very sensitive to the quality of the casting and need to be strictly controlled.

The castings that can be produced by metal mold casting currently have certain restrictions in terms of weight and shape. For example, ferrous metals can only be castings with simple shapes; the weight of the castings cannot be too large; the wall thickness is also limited and small The wall thickness of the casting cannot be cast. Therefore, when deciding to use metal mold casting, the following factors must be comprehensively considered: the shape and weight of the casting must be appropriate; there must be sufficient batches; the deadline for completing the production task is permitted.