Precision casting manufacturer details of the characteristics of the process

The mechanical function of precision casting is higher than that of cast iron, but its casting function is worse than that of cast iron. Because the melting point of precision casting is higher, the molten steel is easy to oxidize, the fluidity of molten steel is poor, the shortening is large, the shortening rate of the body is 10 ~ 14%, the line is 1.8 ~ 2.5%. In order to avoid casting steel casting short, cold isolation, shrinkage cavity and porosity, cracks and sticky sand and other defects.

      It is necessary to adopt a process method that is more messy than cast iron:

1. Because the shortening of precision casting is much greater than that of cast iron, in order to avoid shrinkage cavity and porosity defects in castings, risers, chillers and subsidies are mostly used in casting technology to achieve secondary condensation.

2. Due to poor fluidity of molten steel, in order to avoid cold isolation and casting of cast steel, the wall thickness of cast steel should not be less than 8mm; The structure of the casting system is simple and the section standard is larger than that of cast iron. Choose dry or hot casting mold; Proper pouring temperature, generally is 1520 ° ~ 1600 ℃, because of the high pouring temperature, liquid steel superheat, adhere to a long time, liquidity can be improved. However, if the temperature is too high, the grains will be coarse, hot cracks, pores and sticky sand. So generally small, thin wall and shape messy castings, the pouring temperature is about steel melting point temperature of + 150 ℃; Large, thick wall castings pouring temperature about 100 ℃ higher than the melting point.

In addition, in order to avoid shrinkage cavity, porosity, porosity and crack defects of casting, it is necessary to make its wall thickness uniform, avoid sharp Angle and right-angle structure, add sawdust in molding sand, add coke in mold core, and select hollow core and oil sand core to improve the retreat and permeability of sand or mold core.