the cause of the depression that appears on the smooth surface of the aluminum casting has the following points:

The casting structure is unreasonable, producing hot joints in the local thick parts; the alloy shrinkage rate is large; the gate area is too small; the mould temperature is too high.

Methods for preventing the depression of aluminum castings:

1, improve the casting structure, uniform wall thickness as much as possible, and make use of transitional connections more often.

2, reduce the shrinkage of the alloy.

3, appropriately increase the area of the section of the inner gate.

4, reducing the temperature of aluminum liquid and mould temperature, using temperature control and cooling device to improve the heat balance of the mold, improve the exhaust condition of the mould, and use the paint with less gas.