Zinc alloy is widely used in sanitary ware, bags, shoes and clothing accessories because of its convenient forming, strong plasticity, low cost and high processing efficiency. Die casting is a metal casting process, which is characterized by applying high pressure to the melted metal by using the mold cavity. Molds are usually made of higher strength alloys, which is somewhat similar to injection molding. This article tells you the causes and solutions for blackening of zinc die casting and aluminum die casting.
Most die castings are iron free, such as zinc, copper, aluminum, magnesium, lead, tin and lead tin alloys and their alloys. Depending on the type of die casting, it is necessary to use cold chamber die casting machine or hot chamber die casting machine. If the die castings produced are not handled properly, they will become moldy and black. If such a problem occurs, how should we deal with it? Common causes of mildew and blackening of zinc alloy die castings and aluminum alloy die castings include as follows:
1. External environmental factors. Aluminum is an active metal, which is easily oxidized, blackened or moldy under certain temperature and humidity conditions, which is determined by the characteristics of aluminum itself.
2. Another is its own internal factors. After die casting and machining processes, many manufacturers do not do any cleaning treatment, or simply flush with water, which can not be completely cleaned. There are residual release agent, cutting fluid, specification fluid and other corrosive substances on the surface of die casting aluminum, as well as other stains, which accelerate the growth of mildew spots on aluminum die castings;
3. Unreasonable process design. Improper treatment of aluminum alloy die castings after cleaning or pressure inspection creates conditions for mold of aluminum alloy die castings and accelerates the formation of mold;
4. Improper selection of cutting fluid and cleaning agent. Cleaning is highly corrosive, causing corrosion and oxidation of die-casting aluminum.
5. Warehouse management is not in place. The moldy condition is different when the warehouse is stored at different heights.
From the analysis of the causes of mold of die-casting aluminum, it is not difficult for us to draw such a conclusion: the anti-oxidation problem is not caused by a single factor, it involves internal and external, process, storage and other aspects. At the same time, anti-oxidation needs to be considered in various processes such as cleaning, pressure inspection, storage and transportation. If there is a problem in any link, there will be mold spots for you to see. Therefore, this is a comprehensive problem, and an overall solution needs to be formulated.
From the perspective of cutting fluid, cleaning, lubricity, storage environment and storage mode, the special water-based cutting fluid for zinc alloy solves the problem of mold of zinc alloy die-casting parts, and can provide anti-oxidation solutions for various processes of die-casting zinc cleaning, pressure inspection and storage.
The surface of die-casting zinc alloy products is blackened, especially after machining, which is manifested as black spots and black spots. This may be due to insufficient pressure during die casting and insufficient workpiece density, so pores are formed. This problem will occur after these pores absorb water and are oxidized. Therefore, it is still necessary to solve the problem from the die-casting process.
In addition, impurities and release agents will also cause this situation on the blank surface. If you must use surface treatment to eliminate (cover up), it is recommended that you use natural color anodizing. It’s just that the cost is a little high. Through the above statements, I believe you can further understand zinc alloy die casting and aluminum alloy die casting.