Core tips: zinc alloys are widely used in bathroom, bags, shoes and accessories, because of its convenience, plasticity, low cost and high efficiency.
Zinc alloy is widely used in sanitary ware, bags, shoes and clothing accessories due to its convenient forming, strong plasticity, low cost and high processing efficiency. However, the blistering problem of zinc alloy (electroplating; spraying) has always troubled the friends of hardware factories and electroplating factories
The experience of zinc alloy foaming in electroplating factories of several hardware factories is summarized as follows:
1. At the beginning of the design of zinc alloy products, we should consider the setting of the feeding port, slag discharge port and exhaust port of the mold. Because the flow path of the workpiece with feeding and slag discharging is smooth, there is no air entrapment, no water stains, no dark bubbles, which directly affects whether the subsequent electroplating is bubbling. The workpiece with qualified feeding and slag discharging die casting has smooth surface, white light, and no water stains.
2. In the mold development, we should also consider the tonnage and pressure of the mold mounting machine. We experienced a 20-30% blistering event after zinc alloy electroplating. A hardware factory Friend the first mock exam, and 8 pieces of mold, and how to solve the problem of 20-30% before foaming, and finally block the mold 4 pieces, and change to 4 pieces of mold.
3. The calendering solution, polishing paste and oxide layer on the pretreatment surface are not cleaned, and the surface of the workpiece after calendering and polishing is bright. Many employees in the pickling process of the electroplating plant pickling casually, resulting in the surface attached calendering agent is not cleaned, and long bubbles appear. In addition, there is a great relationship between the calendering agents selected by the calendering and polishing plant, and the surfactants in some calendering agents are very difficult to wash off.
4. Before the product goes into the alkaline copper plating bath, there is still oxide film (pickling film) on the surface of the workpiece. The wax and oil removal film is not treated completely. Therefore, it is very important to remove the film. In the early years, it can also be removed with anti staining salt. Now, it is not allowed to discharge waste water containing anti staining salt. It is recommended to use lj-d009 film removal powder, which has better effect than anti staining salt, can also remove nickel layer, and COD emission meets the national standard International standards
5. There are many organic matters and impurities in the alkaline copper plating bath, and the free cyanide is not in the range. Test the composition of the alkaline copper tank to see if the sodium cyanide is low or the sodium hydroxide is high! If you add the brightener carefully, the brightener is high, and the cleaning of the alkaline copper tank is very important. It is suggested that the carbon treatment should be carried out once every 3-5 days
6. The conductivity of alkali copper cylinder is also very important. Whether the anode dissolves normally and whether the anode copper plate is sufficient will lead to blistering
7. Zinc alloy products blister when they come out of the oven; it may be caused by uneven oven temperature, that is, too high temperature. Because the die casting is not tight, it is easy to put acid into the water stains and trachomas of zinc alloy. Even if there is a surface coating, acid and zinc will still have a chemical reaction, producing a large amount of hydrogen h. When the air pressure inside is higher than atmospheric pressure to a certain extent, and high temperature will produce bubbles
Post time: Mar-15-2021