Aluminum alloy cooling fin was produced by vacuum negative pressure technology

in which gating area of cooling fin was calculated by the Osann equation

and riser size was presented based on the hot spot circle. The numerical simulation was performed to visualize filling and solidification process to predict the potential position of casting defects

and process was optimized. The simulated results reveal that shrinkage porosity （hole） in the cooling fin can be eliminated effectively as a result of defects transferring into the riser by increasing height of static head and enlarging riser size. The optimized process parameters are as follows:pouring time of 3 s

pouring temperature of 740 ℃

hydrostatic head height of 40mm and nine risers with 10 mm. With the optimized processing parameters

smooth filling with entrapment-gas free and splash free is conducted to realize the sequential solidification and feeding

producing successfully the qualified cooling fin.