Under the skin of the casting, the bubbles formed by the accumulation of gas bulge.
Reason for formation:
(1) The mold temperature is too high.
(2) The filling speed is too fast, and the metal liquid is drawn into the gas.
(3) The paint has a large amount of gas and a large amount of water. It is not volatilized before casting, and the gas is wrapped on the surface of the casting.
(4) The exhaust is not smooth.
(5) It is too early to open the mold.
(6) The temperature of the aluminum liquid is high.
(1) Cool the mold to the working temperature.
(2) Reduce the filling speed and avoid eddy entrainment.
(3) Select a paint with a small amount of gas, the amount is thin and uniform, and the mold is completely volatilized.
(4) Clean and add exhaust slots.
(5) Correct the mold opening time.
(6) Correct the smelting process.