Anodizing

Anodizing creates a controlled oxide layer on specific metals for corrosion resistance, wear protection, and cosmetic coloring with good dimensional control.

Overview

Anodizing is an electrochemical process that converts the surface of metals like aluminum and titanium into a controlled oxide layer. This oxide is integral to the base material, not a paint or plated layer, so it adheres strongly and follows the part’s geometry with predictable thickness. You can specify thickness, hardness, and color (dyed or undyed) to balance corrosion resistance, wear life, and appearance.

Use anodizing when you need durable corrosion protection, improved surface hardness, or a consistent cosmetic finish on aluminum or other anodizable alloys. It suits both low and high volumes, from prototypes to production, as long as the part fits in standard tanks and can be fixtured. Tradeoffs include limited material compatibility, reduced electrical conductivity, possible dimensional growth on tight fits, and color variation across alloys and batches. Proper design for masking, racking points, and edge radii is critical to control quality and cost.

Common Materials

  • Aluminum 6061
  • Aluminum 7075
  • Aluminum 5052
  • Titanium Grade 5
  • Magnesium AZ31
  • Zinc alloys

Tolerances

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Applications

  • Machined aluminum housings
  • Extruded structural profiles
  • Consumer electronics enclosures
  • Bicycle and motorcycle components
  • Optical and camera bodies
  • Aerospace brackets and fittings

When to Choose Anodizing

Choose anodizing when working with aluminum or other anodizable alloys that need corrosion resistance, improved wear, or a durable cosmetic finish. It fits parts where a thin, controlled, integral coating is preferred over a thick, layered coating. It works well for medium to high volumes, or repeatable prototypes, as long as you can tolerate some dimensional change and plan for masking and racking areas.

vs Powder Coating

Pick anodizing when you need a thin, tightly controlled coating that preserves fine features, threads, and heat dissipation on aluminum parts. It also performs better where adhesion and abrasion resistance are critical and chipping or flaking of a thicker organic coating would be an issue.

vs E-Coating

Choose anodizing over e-coating when the base metal is aluminum or titanium and you want an inorganic, integral oxide layer rather than an organic paint film. Anodizing is better where you need higher hardness, better wear resistance, or metallic appearance with optional dyeing instead of a paint-like look.

vs Chromium Electroplating

Use anodizing instead of chromium electroplating when you want corrosion and wear resistance on aluminum without handling hexavalent chromium or building a distinct plated layer. Anodizing usually offers simpler environmental compliance and better adhesion on aluminum, at the cost of being limited to certain alloys.

vs Nickel Electroplating

Select anodizing when you prioritize corrosion protection and cosmetic color on aluminum rather than a bright metallic nickel finish or added conductivity. Anodizing keeps coating thickness low and integral, which can simplify tolerance management on precision aluminum components.

vs Physical Vapor Deposition (PVD)

Choose anodizing when you need a cost-effective, robust oxide layer over large batches or larger parts, rather than ultra-thin decorative or functional films. Anodizing lines typically handle higher volumes and larger work envelopes at lower part cost, with less demanding surface prep than PVD requires.

Design Considerations

  • Specify anodize type, thickness range, and color clearly (e.g., Type II, 0.0004–0.0008", black dye) to avoid misquotes and rework
  • Account for dimensional growth: roughly half the coating thickness builds up and half penetrates; open fits and tight bores may need machining allowance
  • Add generous radii and avoid sharp edges where possible to reduce burning, thin spots, and chipping in service
  • Define masked and contact areas on the drawing so the shop can plan racking, plugging, and masking labor accurately
  • Keep deep blind holes, narrow slots, and enclosed pockets to a minimum or add vent paths to improve solution flow and coating uniformity
  • Call out alloy and temper explicitly, since color, coating quality, and hardness vary significantly between aluminum grades