Cast iron process can be divided into three basic parts, namely, cast iron preparation and cast iron treatment. Cast metal refers to the metal material used in cast iron production, which is composed mainly of a metal element. Alloys formed by addition of other metal or non-metallic elements, customarily called cast iron alloys, mainly cast iron, cast steel, and cast non-ferrous alloys.
1. Characteristics of foundry production
The forming of cast iron is a process from liquid condensation to solid state. It is an important process for manufacturing blank or parts of mechanical parts. It has the following advantages:
（1）Can manufacture various sizes and shapes of cast iron, especially cast iron with complex inner cavity.
（2）Cast iron can be made from common metal materials, and some materials (such as cast iron, bronze) can only be made by cast iron.
（3） the raw materials used in foundry are widely used, low price and can be recycled, so the cost of cast iron production is low, so it is widely used in machine manufacturing, for example, it is 60% in machine tool.
（4）the shape of cast iron is close to the size of parts, which can save metal consumption and reduce cutting cost.
The main shortcomings of foundry production are: the process of cast iron production is complicated and the working procedures are many. The shrinkage holes, shrinkage holes, sand holes, cold seperation often occur because of the difficulty of comprehensive control in the technological processes of cast iron materials, moulds, cast iron alloys, melting and pouring of alloys, etc. Therefore the cast iron quality is not stable and the mechanical properties of the cast iron are not as good as the forgings of the same materials.
2. Classification of cast iron
Generally, cast iron is classified according to modeling method, which is usually divided into sand mold cast iron and special cast iron. Sand mold cast iron includes wet sand mold, dry sand mold and chemical hardened sand mold. We use dry sand mold cast iron.