Characteristics of Investment Casting Process

Characteristics of Investment Casting Process

Characteristics of Investment Casting Process
1. Due to the poor fluidity of molten steel, in order to prevent cold insulation and insufficient pouring, the wall thickness of precision castings should not be less than 8mm. The structure of the casting system is simple and the section size is larger than that of cast iron. Dry cast or hot cast type is adopted. , properly increase the pouring temperature, generally 1520°C - 1600°C. Due to the high pouring temperature, the molten steel has a high degree of superheat and a long liquid retention time, and the fluidity can be improved. However, if the pouring temperature is too high, defects such as coarse crystal grains, hot cracks, pores and sand sticks may be caused. Therefore, the precision castings of small, thin-walled and complex shapes generally have a casting temperature of about 150°C. The casting temperature of large and thick-walled castings is about 100°C higher than the melting point.
2. Since the shrinkage of cast steel greatly exceeds that of cast iron, in order to prevent the shrinkage and shrinkage defects of precision castings, the riser and cold iron and subsidies are mostly used in the casting process to achieve sequential solidification. In addition, in order to prevent shrinkage, shrinkage, porosity and crack defects in the steel castings, the wall thickness should be uniform, avoid sharp corners and right angle structures, add sawdust in the molding sand, add coke in the core, and Hollow cores and oil sand cores are used to improve the retractability and gas permeability of the sand or core.