1. Under-casting (under-filling, unclear outline, corner defects)
Reason for formation:
(1) The fluidity of the aluminum liquid is not strong, the gas content in the liquid is high, and the scale is large.
(2) The cause of the casting system is bad. The inner gate section is too small.
(3) Reasons for poor exhaust conditions. The exhaust gas is not smooth, the coating is too much, and the mold temperature is too high, so that the gas pressure in the cavity is high, so that the gas is not easily discharged.
(1) Improve the fluidity of aluminum liquid, especially refining and slag. Appropriately increase the temperature and mold temperature. Increase the casting speed. Improve the structure of the casting, adjust the thickness allowance, and set the auxiliary rib channel.
(2) Increase the cross-sectional area of the ingate.
(3) Improve the exhaust condition, add a liquid flow tank and an exhaust line, and open a vent plug at the deep concave cavity. Make the coating thin and uniform, and then mold it after drying.