For large castings, the most basic point of view is to solve the “thermal balance” of casting shrinkage defects. In the solidification process of large castings, the size of each part is usually reduced. The percentage of casting size shrinkage is called casting linear shrinkage or casting shrinkage. When manufacturing the mold (including the core box), the mold must be expanded according to the determined shrinkage rate of the casting to ensure that the size of the cooled casting meets the requirements.

Large casting is the process of melting metal into a liquid that meets certain requirements and pouring it into the mold. After cooling, curing and cleaning, castings with predetermined shape, size and properties are obtained. Casting is one of the basic processes of modern machinery manufacturing industry. Casting is a relatively economical method of forming billets, and it can show more economy for parts with complex shapes. Large castings, such as machine tool castings, have their own unique advantages, which are easy to operate and save time, but also increase production. The high surface smoothness makes large castings well received by users in the process of more use.