Do you know the uses of large cast iron platforms?
Thermal cracks in large cast iron platforms form within the solidification temperature range but close to the solidus temperature, at which point the alloy is in a solid-liquid state. Secondly, cracks form slightly below this temperature, when the alloy is in a solid state. Preventive measures for cracks in large cast iron platforms: Ensure the quality of melting for large cast iron platforms. In the alloy composition of large cast iron platforms, sulfur is a harmful chemical component. When wS > 0.03, with a critical aluminum content of 0.05 distributed in a chain-like eutectic form, the plasticity of the large cast iron platform is very low, making it prone to thermal cracks.
The compactness of the sand mold and sand core for large cast iron platforms is low or uneven, with local looseness. Complex mold shapes, pits, and corners are difficult to compact. Improper selection of molding equipment parameters, low molding pressure, poor fluidity, and difficulty in filling may result in low sand mold compactness. Low compactness of the sand core for large cast iron platforms may be due to poor exhaust in the core box and low sand shooting pressure during the core-making process. Poor mold quality, uneven coating thickness, and coating peeling. The workshop uses alcohol-based coatings for spraying sand molds. Due to low compactness near the parting surface of the upper mold, spraying and drying of large cast iron platforms can easily cause issues. In the original process, the upper mold was sprayed less, and areas prone to sand collapse were not sprayed.

Melting metal for large cast iron platforms is not just simple melting but also involves a smelting process to ensure that the metal poured into the mold meets the expected requirements in terms of temperature, chemical composition, and purity. For this purpose, various quality control inspections and tests are conducted. The molten metal for large cast iron platforms must meet all specified indicators before it is allowed to be poured. Sometimes, to meet high requirements, the molten metal undergoes treatments such as desulfurization, vacuum degassing, external refining, inoculation, or modification. Commonly used equipment for melting metal in large cast iron platforms includes cupola furnaces, electric arc furnaces, induction furnaces, resistance furnaces, and reverberatory furnaces.
Mechanical sand sticking and damage-related sand sticking in large cast iron platforms have different mechanisms, some even opposing, and many factors influence sand sticking. Only through rigorous analysis, verification, identification of key factors, and improvements can the surface quality and precision of the platform be better controlled. Low pouring temperature for large cast iron platforms prevents the molten metal at the filling front from fully vaporizing the foam. Unvaporized residues do not have time to float to the top or risers, and vaporized residues cannot be expelled from the mold in time, solidifying in the casting.
Insufficient refining of the alloy melt results in a large amount of gas or gaseous substances, leading to the formation of gas pores or reaction pores in large cast iron platforms. Inadequate drying of molds and cores, poor permeability, poor ventilation, excessive moisture and gas-generating substances, un-dried coatings or coatings with excessive gas-generating components, un-dried chills and core supports, and poor exhaust in metal molds for large cast iron platforms can cause invasive pores in castings. Low pouring temperature, low metal mold temperature, and poor slag removal from molten metal.
During melting, an appropriate amount of strong desulfurizing rare earth elements can be added to reduce the sulfur content in the alloy. With a reasonable addition process, the desulfurization effect is significant. The design of the gating system and risers for large cast iron platforms may cause thermal and mechanical hindrances during casting shrinkage. Areas near the ingate solidify later, and these weak spots in large cast iron platforms are prone to thermal cracks. By dispersing the ingates and allowing molten metal to enter the mold cavity from multiple points, thermal stress can be distributed, reducing thermal hindrances during shrinkage of large cast iron platforms and preventing or minimizing thermal cracks.
Weiyue Machinery, Ms. Xie, 15350773479