Generally speaking, the riser should be set at the hot joint of steel castings, that is, the final solidification area. Therefore, in the riser design, the solidification time of each part of the steel casting should be calculated first to find the position of the hot joint of the steel casting. The solidification time of steel casting is directly proportional to its modulus value. Therefore, the solidification sequence can be determined by the modulus value of each part of steel casting, and then the position of hot joint of steel casting can be determined. The feeding channel is located at the hot joint of the steel casting, and its temperature is higher than that of the non feeding channel. The solidification speed is slow and the solidification time is long. If the feeding liquid metal is not available during the solidification of the steel casting, shrinkage porosity and shrinkage cavity will appear at this position.
When designing the feeding system of steel casting process, it is necessary to decompose the steel casting with complex shape into multiple substrates with simple shape. By calculating the modulus of each substrate, the modulus of each part of the steel casting can be obtained, so as to determine the position of the hot joint of the steel casting.