Zinc Electroplating

Zinc electroplating deposits a thin sacrificial zinc layer on metal parts for low-cost corrosion protection and cosmetic appearance in high-volume production.

Overview

Zinc electroplating applies a thin zinc layer onto metal parts using an electrolytic bath. The zinc coating provides sacrificial corrosion protection, meaning the zinc corrodes first to protect the underlying steel or iron. Typical coating thickness ranges from about 5–25 µm, often with post-treatments like clear, yellow, or black passivation to boost salt-spray performance and tune appearance.

Use zinc electroplating for high-volume hardware, brackets, and stamped parts where you need economical corrosion resistance and a clean, uniform finish. It works well for small to medium steel parts, including bulk barrel-plated fasteners and rack-plated components with more cosmetic requirements. Tradeoffs include limited wear resistance, risk of hydrogen embrittlement for high-strength steels (requiring bake-out), and reduced coverage in deep recesses or sharp corners. Dimensional buildup is small but should be considered on tight fits and fine threads. For most industrial hardware, zinc electroplating gives a strong cost-to-performance balance and broad supplier availability.

Common Materials

  • Low-carbon steel
  • Alloy steel
  • Stainless steel 304
  • Cast iron
  • Brass

Tolerances

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Applications

  • Bolts, nuts, screws, and washers
  • Stamped brackets and clips
  • Automotive clamps and spring clips
  • Hydraulic and pneumatic fittings
  • Electrical and cable hardware
  • Hinges, latches, and small assemblies

When to Choose Zinc Electroplating

Use zinc electroplating when you need economical corrosion protection on steel or iron parts, especially small hardware and stamped components. It is ideal for medium to very high volumes, where thin, uniform coatings, cosmetic appearance, and good salt-spray performance matter more than extreme wear resistance or thick barrier coatings.

vs Anodizing

Choose zinc electroplating over anodizing when you are coating steel, cast iron, or brass, where anodizing is not applicable. Zinc plating gives sacrificial corrosion protection and is better suited to fasteners, brackets, and general hardware that are not aluminum-based.

vs Powder Coating

Choose zinc electroplating when you need a thin, controlled coating for threads, tight fits, or small hardware where powder coating would be too thick. Zinc plating is also more cost-effective for very high-volume small parts that can be barrel plated.

vs E-Coating

Choose zinc electroplating when sacrificial protection of steel is a priority and part geometry is simple enough for good zinc coverage. It is often more economical for small components and fasteners, while still offering strong corrosion resistance with appropriate passivation.

vs Nickel Electroplating

Choose zinc electroplating instead of nickel electroplating when corrosion protection and cost matter more than hardness and decorative appearance. Zinc plating is typically cheaper and better suited for general-purpose industrial hardware rather than wear or high-end decorative applications.

vs Physical Vapor Deposition (PVD)

Choose zinc electroplating when you need low-cost, sacrificial corrosion protection in bulk quantities, not ultra-thin decorative or functional hard coatings. Zinc plating is far more economical for large batches of fasteners, brackets, and general steel components.

Design Considerations

  • Specify coating thickness range and passivation type (e.g., clear, yellow, black) in the drawing notes to avoid guesswork and inconsistent finishes
  • Avoid extremely tight thread tolerances or press fits without allowing for plating buildup, especially on small fasteners and precision bores
  • Design parts and racks to avoid deep blind recesses and tight corners where coverage will be poor and burn or bare spots are likely
  • Call out masking requirements only where critical; excessive masking increases labor and cost significantly
  • Identify high-strength steels (typically > HRC 32) and specify hydrogen embrittlement relief baking where required by standards
  • Provide clear indication of cosmetic surfaces versus non-critical areas so the plater can orient parts and rack them to prioritize appearance where it matters