Internal defects of die-cast parts: Treatment methods for non-metallic hard points

① During casting, avoid scooping the oxides on the surface of the alloy liquid into the ladle;
② Remove the oxides on the surface of the iron crucible and apply a coating; promptly clean the residues on the furnace walls and bottom;
③ Remove the oxides on tools such as ladles;
④ Use refractory materials that do not react with aluminum;
⑤ Ensure the purity of the metal materials.