We have X-ray inspections for die casts, and find some inner defects such as shrinkage cavities, blow holes and shrinkage porosity existing in die casts after die casts are manufactured. We put forward the following corresponding countermeasures in order to improve defects and quality of die casts.

1. Improving the structure of the overflow box
The overflow box has the effects of eliminating the gas in the cavity, storing the mixed gas and transferring the shrinkage cavity and the shrinkage porosity. We find that we can improve defects such as shrinkage cavities and blow holes by extending and adding overflow boxes after repeated experiments. Usually, vertical overflow gates should be chosen because of much shrinkage porosity in the middle of die casts so as to avoid filling pressure being affected.

2. Optimizing the cooling system of the mold
Shrinkage cavities of die casts often occur in positions where partial temperatures of die casts are too high or walls of die casts are too thick. After the research, we find that temperatures at two sides of die casts' thick walls are high, which will easily cause shrinkage cavities. We select the smallest die cooling pipe with the diameter of 12mm at the beginning, and it can't cool the temperature of the above positions. Therefore, we adopt the high-pressure cooling equipment and the stainless steel die cooling pipe with a diameter of 4mm to improve the structure of the die cooling pipe. We cool temperatures of mold cores of die cast's two sides to 180℃, which can greatly reduce shrinkage cavities and improve quality of die casts.
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