The problems with aluminum alloy die-cast parts include: flow marks and patterns.

(1) Characteristics:
There are stripes on the surface of the casting indicating the direction of metal liquid flow, or there are undirected lines. These lines are different in color from the metal matrix and show no obvious trend.
(2) Causes of occurrence:
① The metal liquid forms a thin and incomplete layer first in the mold cavity, which is left as a trace after being filled by subsequent metal liquid;
② The mold temperature is too low or uneven;
③ The cross-sectional area of the internal riser is too small or the position is inappropriate, resulting in splashing;
④ Insufficient filling pressure of the metal liquid;
⑤ Pattern: Excessive amount of coating.