How to prevent streaks in precision casting and why

Precision casting is a general term for the process of obtaining precise size castings. Compared with the traditional sand casting process, the castings obtained by precision casting have high dimensional accuracy and good surface finish. Its products are exquisite and complex. It is similar to the shape of the part and can be used directly without processing or processing. Therefore, investment casting is an advanced near-net-forming technology. However, streaks may appear during the casting process. What are the reasons?

1. The traces left by two metal streams when filling the cavity.

2. The mold temperature is low. If the zinc alloy mold temperature is lower than 150°C and the aluminum alloy mold temperature is lower than 180°C, the above defects are prone to occur.

3. The filling speed is too high.

4. Excessive coating.

Elimination measures

1. Adjust the cross-sectional area or position of the inner gate.

2. Adjust the mold temperature and enlarge the overflow groove.

3. Properly adjust the filling speed to change the flow state of the filled metal liquid.

4. The coating is even and thin.