Determining a reasonable pouring temperature is an important condition for ensuring the quality of gray iron castings.

The pouring temperature significantly affects the quality of gray iron castings, yet it is often overlooked by technicians—especially furnace operators at small to medium-sized foundries, who, lacking solid technical knowledge, rely on intuition to control molten iron temperature instead of systematically recording and testing it.

There are three reasons for this situation: 1、 Some small- and medium-sized foundries are not equipped with thermometers. Without temperature-measuring devices, foremen cannot monitor the molten iron. Although thermometers are inexpensive, portable models still cost over 1,000 yuan. Yet, the owners of these casting plants have a poor awareness of quality. Over time, such facilities will be limited to producing only standard castings. 2、 Some foundries are equipped with thermometers, but due to the lack of an effective temperature-monitoring system, furnace operators often fail to follow the proper temperature-measurement procedures when checking molten iron—sometimes skipping measurements altogether, or recording data carelessly and inaccurately. As a result, the molten iron temperature frequently deviates significantly from the required casting temperature, leading to a high rate of defective castings and causing substantial financial losses for the foundry. 3、 Another reason is that the furnace workers have limited experience and haven’t acquired systematic knowledge of casting. They’re unclear about the precise pouring temperatures required for different materials, varying wall thicknesses, and distinct chemical compositions, which can easily lead to defects if the pouring temperature isn’t properly controlled.

When the pouring temperature exceeds the required level for gray iron castings, defects such as shrinkage cavities and porosity are likely to occur, leading to insufficient self-repair capability of the cast iron. This issue becomes particularly pronounced in thicker castings. Therefore, for wall thicknesses exceeding 20 Castings measured in millimeters require the pouring temperature to be precisely controlled within the specified range. It’s also important to remember that, at the same pouring temperature, melting iron in an electric furnace versus melting it in a cupola furnace will yield different casting results. For instance, in a cupola furnace, when the molten iron reaches a temperature of 1300–1320 When measuring, with the same wall thickness 10 Millimeter-sized castings exhibit excellent fluidity, and the gray iron casting products meet quality requirements. However, when using an electric furnace for melting, the molten iron must be heated to a higher temperature—provided that the casting and wall thickness remain identical. 20-30 Degree, which can ensure a better flow temperature. This is related to the melting characteristics of the medium-frequency induction furnace and its degree of supercooling.

Low pouring temperature can lead to issues such as cold shuts, insufficient filling, slag inclusions, and manganese sulfide porosity. This occurs because the lower molten iron temperature causes rapid cooling of the metal. After the molten iron is poured into the mold, its temperature falls below the required casting range, preventing it from completely filling the mold and resulting in inadequate casting. Moreover, due to the cooler temperature of the poured iron, impurities and slag fail to fully rise to the surface, leading to incomplete removal of slag and leaving behind troublesome slag inclusions in the gray iron casting. Low molten iron temperatures pose a particularly significant risk for thin-walled castings—especially those with wall thicknesses less than 5 mm Thin-walled castings can develop numerous defects if the pouring temperature is not properly controlled—such as poor surface quality, chilling, improper microstructure, and excessive carbide formation. Therefore, in the production of gray iron castings, establishing a reasonable pouring temperature is a critical factor in ensuring product quality. Indeed, every type of gray iron casting requires an optimal pouring temperature, and identifying this ideal temperature demands that our casting technicians conduct repeated preliminary trials, followed by meticulous comparative analyses and data-driven insights to pinpoint the perfect pouring setting.