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The precision casting process should pay special attention to the following two points

Posted by: Fymicohuang 2021-05-31 Comments Off on The precision casting process should pay special attention to the following two points

Precision casting parts use silica sol precision casting parts processing technology, we have a full set of equipment and material composition testing equipment. The processing equipment is automatically controlled from wax melting, injection, dewaxing, roasting, and casting. For each furnace of molten steel of different materials, a spectrometer is used to perform on-site material composition determination and analysis. Precision die casting is absolutely not allowed if the material composition is insufficient or too high, ensuring the quality and reliability of the equipment from the source

  1. Due to the poor fluidity of molten steel, in order to prevent the cold barrier and insufficient pouring of the steel castings of precision castings, the wall thickness of the steel castings should not be less than 8mm; the structure of the pouring system should be simple and the cross-sectional size should be larger than that of cast iron; Dry casting or hot casting; appropriately increase the pouring temperature, generally 1520°~1600°C, because the pouring temperature is high, the molten steel has a high degree of overheating, and the liquid state is maintained for a long time, and the fluidity can be improved. However, if the pouring temperature is too high, it will cause defects such as coarse grains, thermal cracks, pores and sand sticking. Therefore, the casting temperature of small, thin-walled and complex-shaped castings is about the melting point temperature of steel + 150°C; the casting temperature of large, thick-walled castings is about 100°C higher than its melting point.
  2. Since the shrinkage of cast steel greatly exceeds that of cast iron, in order to prevent shrinkage and porosity of castings, risers, chilled iron, and subsidies are mostly used in the casting process to achieve sequential solidification. In addition, in order to prevent the occurrence of shrinkage cavities, shrinkage porosity, pores and cracks in steel castings, the wall thickness should be uniform, sharp corners and right-angle structures should be avoided, sawdust is added to the casting sand, coke is added to the core, and Use hollow cores and oil sand cores to improve the retreatability and air permeability of sand molds or cores.

The casting steel of precision casting has a high melting point and correspondingly its pouring temperature is also high. At high temperatures, molten steel interacts with the mold material, and it is easier to produce sticky sand defects. Therefore, artificial quartz sand with higher refractoriness should be used as the mold, and the surface of the mold should be brushed with a coating made of quartz powder or zircon sand powder.

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