2025-06-17
• Feature: There are small bumps on the surface of the casting, with cavities formed beneath the surface.
• Causes: The filling degree of the alloy liquid in the die cavity is too low, which easily leads to entrained gas; the injection speed is too high; the mold has poor exhaust performance; the molten liquid is not degassed, and the melting temperature is too high; the mold temperature is too high, the metal solidification time is insufficient, the strength is not sufficient, and the mold is opened too early to remove the casting, causing the compressed gas to expand; there is too much release agent; the internal gate is set improperly, and the filling direction interface is not smooth.
• Solution: Reduce the diameter of the die cavity, increase the filling degree of the molten metal; extend the injection time, reduce the injection speed in the first stage, change the switching point between low-speed and high-speed injection; lower the mold temperature, maintain thermal balance; add exhaust grooves and overflow grooves to ensure thorough exhaust, promptly remove the oil stains and waste materials on the exhaust grooves; adjust the smelting process and perform degassing treatment; appropriately extend the mold holding time; reduce the amount of release agent.