Why does the casting shrink?

When cooling and solidification treatment is carried out by iron casting manufacturers, the shrinkage rate of castings is the most important consideration. Shrinkage refers to the percentage of size reduction of alloy castings during solidification. Shrinkage has an important influence on the precision of castings. Then, what are the reasons for shrinkage change of castings?

1. Influence of casting structure. The more complex the structure of the casting is, the more difficult the shrinkage is, and the shrinkage rate will decrease. The shrinkage of steel castings casted with the same composition is different because of their different structural shapes.

2. Influence of material selection. During the production of iron castings, due to the different compositions of the selected materials, the shrinkage of castings will be different. Generally, the shrinkage of alloy castings is better than that of gray cast iron. However, when the sulfur element in gray cast iron increases and the silicon element decreases, the shrinkage of castings will increase.

3. The influence of metal's concession. The shrinkage of alloy metal castings will increase with good yield. With the increase of casting size, the castability of the mold will become worse, and the shrinkage of the casting will become smaller.