It is found that only a small amount of shrinkage porosity occurs at the inner runner when observing the inside of the sand casting by using the X-ray perspective internal view (Figure 1). According to the observation of the solidification time of the 2D section of the casting (Figure 2), the inside of the sand casting near the riser does not affect the use of the flywheel.

According to the above analysis, in order to improve the feeding distance of the riser, the reasonable use of cold iron will play a vital role. The riser and cold iron will be used together to improve the solidification sequence of the sand casting. Under the same pouring conditions, the improved scheme can greatly reduce the defect of the ductile iron flywheel. This flywheel is a product provided by ZHY Casting. From product part drawing to 3D design and mold design, it has passed the acceptance after trial production, which shows that this process plan is feasible and can cast sound sand castings with good surface quality. After trial production, the mechanical properties can meet the design requirements, and it has passed the acceptance, and is officially put into production.