For less complex steel castings, in order to save man hours and improve the quality of steel castings, the number of sand cores should be reduced as much as possible. The position of the sand core in the sand mold is generally fixed by the core head, and it is also fixed by core support and iron wire. For steel castings with high requirements, core support shall not be used as much as possible. For the fine and high vertical sand core, the diameter of the lower core head is often appropriately increased to position the sand core. According to the position of the sand core in the sand mold, the core head can be divided into two categories: vertical core head and horizontal core head.
When casting steel castings, the sand core under the action of high-temperature liquid metal will produce a large amount of gas instantaneously due to the evaporation of water and the combustion, decomposition and volatilization of organic matter. When the exhaust of the sand core is poor, the gas will enter the liquid metal, so that the steel casting contains a large number of pores after solidification. Therefore, necessary measures should be taken in the structural design, processing and manufacturing of sand core, as well as the operation of core lowering and mold closing, so that a large amount of gas generated during pouring can be discharged from the core head in time and smoothly.