To prevent "surface pinholes" and "bubbles" in lighting fixture die castings during production, the key is to fundamentally control the introduction and discharge of gas.
Alloy Melting Process: Use high-purity raw materials and auxiliary materials to reduce gas generated by impurities. During the alloy melting process, inert gas (such as nitrogen) degassing or degassing agents should be used to reduce the hydrogen content in the molten alloy, preventing the formation of bubbles during the solidification process.
Die Casting Process: Preheat the mold to an appropriate temperature to avoid the molten alloy solidifying immediately upon contact with the cold mold, which would trap gas and prevent its discharge. Control the injection speed and pressure to ensure the molten alloy fills the mold cavity smoothly—high-speed injection that entrains air should be avoided, as this can cause pinholes. For castings with complex structures, vacuum die casting can be adopted to evacuate gas from the cavity, thereby reducing defects. In addition, the mold cavity should be finely polished; a smooth surface facilitates gas discharge and prevents gas from being "trapped" by a rough surface, which would otherwise lead to pinholes.
