The manufacturing process of zinc alloy labels encompasses die casting, surface treatment (such as electroplating), and precision machining (such as laser engraving). Through the collaborative efforts of multiple processes, high-precision, durable, and decorative metal markings are achieved.
1.Die Casting: The Core of High-Precision Molding
The main body of the zinc alloy label is manufactured using a high-pressure die casting process. Molten zinc alloy (common grades such as YZZnAl4A) is injected into a precision mold cavity at high speed and pressure. After rapid cooling, a blank with complex shapes and uniform wall thickness is obtained. This process supports a minimum wall thickness of 0.3mm and can accurately replicate details such as logos, text, and embossed textures.
Key Mold Design Points: Optimize the parting surface and gating system to avoid flash and porosity; use sliders or core-pulling mechanisms for structures with undercuts to ensure smooth demolding.
Parameter Control Points: Injection temperature should be controlled between 430–450℃; holding pressure and time must be matched to the part thickness to prevent shrinkage cavities and deformation.
Post-processing and initial finishing: Removing gates and burrs is often done by vibratory grinding (ceramic beads, 1–3 mm) or ultrasonic cleaning. Manual finishing uses diamond files to treat local residues.
2.Surface Treatment: Enhancing Corrosion Resistance and Decorative Appearance Die-cast labels require multi-stage surface treatment to improve protective performance and meet visual requirements, with electroplating being one of the core processes.
Pre-treatment Process: This includes ultrasonic dewaxing → hot water washing → chemical degreasing → cathodic electrolytic degreasing → activation → pre-immersion, ensuring the substrate is clean and free of oil, providing good adhesion for subsequent plating layers.
Electroplating Process Selection:
Decorative Plating: A common combination is "pre-plating copper (5–10μm) → bright nickel plating → chromium plating (>0.25μm)," forming a multi-layered copper/nickel/chromium structure that combines high gloss and corrosion resistance.
Environmental Trends: Cyanide-free electroplating processes (such as pyrophosphate systems) are gradually replacing traditional cyanide plating solutions, complying with RoHS directives and suitable for export products.
Other surface treatments: PVD coating (such as gold, rose gold), oxidation coloring or spraying can also be performed to achieve special visual effects such as antique bronze and matte black.