Common defects in investment casting: how to avoid streaks

Streaks are one of the common defects in investment casting, which are usually caused by factors such as overcooling or uneven cooling of the molten metal. Here are some ways to prevent streaks:

1. Maintain an appropriate pouring temperature: If the temperature of the molten metal is too low, the mold shell will solidify unevenly and easily lead to streaks. Therefore, maintaining an appropriate pouring temperature is one of the keys to avoiding streaks.

2. Control the quantity and location of pouring bars: The main function of pouring bars is to enhance the strength and stability of the model and attachment area. However, too many pouring bars and unreasonable positions will cause the molten metal to cool too much and cause streaks.

3. Control the flow and speed of liquid metal: Excessive flow and speed of liquid metal will cause the supercooled metal to solidify in the thicker shell, causing streaking problems. Therefore, the flow and speed should be appropriately controlled.

4. Use heaters and coolers: Heaters and coolers can be used to adjust the temperature and flow rate of the liquid metal before or during the injection process, so as to better control the temperature distribution and flow rate of the liquid metal within the model. Flow shape to reduce the occurrence of streaks.

5. Keep the model surface smooth: The unevenness and roughness of the model surface will cause uneven flow of molten metal and premature solidification, resulting in streak problems. Therefore, the model surface should be kept as smooth and flat as possible.

All in all, if you want to avoid streaks in precision casting, you need to master the appropriate operating methods and production techniques, strengthen the control and adjustment of parameters such as the temperature, flow rate, and flow rate of the molten metal, and at the same time strengthen the detailed management of the model surface and the flow state of the liquid metal. , thereby minimizing the appearance of streaks.