For a long time, the main and frequent defects (foaming) of zinc alloy die-casting parts have plagued many die-casting practitioners and die-casting processing enterprises. At the same time, this has also caused peeling between large raw material suppliers and die-casting companies, polishing and electroplating companies, and small business sectors.
Zinc alloy die castings are currently widely used in various decorations, such as furniture accessories, architectural decoration, bathroom accessories, lighting parts, toys, tie clips, belt buckles, various metal decorative buckles, etc. The surface quality requirements are high, and at the same time good surface treatment performance is required. The common defect of zinc alloy die-casting parts is surface blistering.
Caused by incorrect post-processing techniques
(1) Polishing
For example, polishing intensity; some of them are calendering (the stone used and specifications, "granite ceramics"), vibration (the specifications of the abrasive used, the amplitude of vibration, the frequency of vibration).
(2) Polishing
The specification and model of the polishing wheel, as well as the strength of the polishing (too much force will destroy the hard layer, if it is too light, the polishing effect will not be achieved).
(3) Degreasing and cleaning
Since some auxiliary materials (wax, vibration fluid, etc.) are used when grinding or polishing, and these auxiliary materials will remain on the surface of the die-casting part, it needs to be cleaned. Usually, lye, acid and electrolytic degreasing are used.
The main components of zinc alloy die-casting parts are zinc and aluminum. Segregation occurs during the die-casting process, and there will be zinc-rich or aluminum-rich phenomena in some parts of the product. Alkali can make aluminum, and acid can make zinc preferentially dissolve. Pinholes will be formed on the surface of the product, the solution will remain between them, and bubbles are likely to be generated after electroplating, so the cleaning and degreasing of zinc alloy die-casting parts is very important.
(4) Process and storage
A. It cannot be stored after die-casting, resulting in water absorption and oxidation;
B. After polishing, the electroplating treatment was not carried out in time, resulting in oxidation of the product surface;
C. After cleaning and degreasing, timely electroplating will not cause corrosion of the product surface;
D. After the electroplating is completed, it is not stored as required.
