What are the requirements for molding sand for cast iron platforms?

What are the requirements for molding sand for cast iron platforms?

Sand is the main shaping material for cast iron castings and has a significant impact on the quality of the castings. The performance requirements for sand cast iron castings include the following aspects:

1. Chemical composition of molding sand for cast iron platforms: Quartz sand is generally used as a raw material for producing gray cast iron platforms, with a mass fraction of 90% -95% silicon dioxide.

2. The particle size and shape of cast iron platform sand: In rivet platform castings, the decomposition of the rivet platform model during the pouring process mainly depends on the coating and molding sand. For clean molding sand, its permeability depends on the size of the sand particles, usually between 30-70 sieves. Round sand is generally used due to its good fluidity, density, and high permeability.

3. Moisture in cast iron platform sand: The moisture in the sand is the root cause of many casting defects in cast iron platforms. The use of dry sand without moisture also means that a large amount of heat required for gas moisture can be reduced, which is beneficial for the gasification conditions of the cast iron platform model and ensures the quality of the casting. The ideal molding sand has no moisture, but due to atmospheric humidity and condensation, there may be trace amounts of moisture. Therefore, the moisture content of cast iron platform molding sand should be less than 1%.

4. The mud content of casting sand: Due to the thermal effect of high-temperature metal liquid, certain components in the casting sand gasify and produce a large amount of gas, while forming high pressure. The mud content of molding sand should be less than 1% -3%, and sand can generally be washed with water.