It was found that the entire cast solidification started in a short time after being filled based on the numerical simulation under the conditions of low pressure casting.The difference of the solidification in solidification came from the solid content in different position varied with the cooling condition.The formation of the shrinkage was attributed to cooling curve in the feeding zone partly coincidences with that in needed feeding zone.The insulation layer was designed to set on the positions corresponding to the wheel rib in the upper core and bottom core

which made position of the cooling curve at the spoke increase

realizing cooling curves separation between the spoke and conjunction location of the rib and elimination of the shrinkage porosity（holes） at the conjunction.The temperature in the area of mold being covered by the insulation boards was raised by approximately 20 ℃.