1. Insufficient coating of zinc alloy die casting products causes yellowing;
2. The high porosity of the coating leads to yellowing;
3. There are impurities in the plating solution, which are contaminated to cause yellowing of the die casting products;
4. Insufficient electroplating time will also cause yellowing of zinc alloy die casting products;
5. Insufficient washing after electroplating leads to yellowing;
6. Storage in a messy and dirty space after electroplating will also cause yellowing of zinc alloy die casting products.
1. The process technology is not scientific. The negligence of aluminum alloy die casting products after their cleaning or pressure inspection creates conditions for their growth of mildew and blackening, and accelerates the conversion of mold.
2. The logistics and warehousing management is not timely. If aluminum alloy die casting products are stored in warehouses with different aspect ratios, the mold growth will be different.
3. The internal elements of aluminum alloy profiles. Some die casting factory of aluminum alloy profiles do not do everything to clean up after the aluminum die casting and mechanical processing process, or simply rinse with tap water, which cannot guarantee complete cleaning. The surface layer of die casting products contains corrosive chemicals and other dirt such as release agents, cutting oil, soap liquid, and other dirt. That dirt accelerates the growth rate of mildew dots and the blackening of aluminum alloy die casting products.
4. Environmental factors of aluminum alloy profiles. Aluminum is an active metal. Under certain temperature and environmental humidity standards, it is very susceptible to air oxidation and blackening or mildew. This is determined by the characteristics of aluminum itself.
5. Improper use of cleaning agents. The cleaning agent used is highly corrosive, causing corrosion and oxidation of die casting products.