Anodizing

Anodizing forms a hard, corrosion-resistant oxide layer on metals—most often aluminum—improving wear, appearance, and dyeability with minimal dimensional change.

Overview

Anodizing is an electrochemical conversion coating that grows a controlled oxide layer from the base metal (most commonly aluminum, also titanium and others). The layer is integral to the substrate, improves corrosion resistance, increases surface hardness (especially hardcoat), and can be dyed for durable color and branding.

Choose anodizing for lightweight metal parts that need robust corrosion protection, a clean cosmetic finish, or electrical insulation on the surface. It fits prototypes through production, with good repeatability and relatively low per-part cost when racking is efficient.

Tradeoffs: coverage depends on line-of-sight current flow and racking, so contact marks are expected and must be planned. Thickness grows partly into the material and partly outward, so tight fits, threads, and precision bores may need masking or post-process sizing. Dyes can fade under UV depending on type and color, and cosmetic variation can occur across alloys, heat treat, welds, and mixed lots.

Common Materials

  • Aluminum 6061
  • Aluminum 7075
  • Aluminum 5052
  • Titanium Grade 5
  • Magnesium AZ91
  • Niobium

Tolerances

±0.001" to ±0.003" (dimensional change from coating buildup; depends on anodize type/thickness and masking)

Applications

  • Black anodized electronics enclosures
  • Hard-anodized hydraulic manifolds
  • Anodized aluminum bicycle components
  • Colored aerospace brackets and clamps
  • Laser-etched anodized nameplates
  • Titanium medical instrument handles

When to Choose Anodizing

Pick anodizing for aluminum or titanium parts needing corrosion resistance, surface hardness, or a durable dyed finish without adding a separate paint layer. It’s a strong fit for production hardware and fielded products where handling, abrasion, and environmental exposure matter. Plan it early when the design has tight fits, critical threads, or cosmetic requirements so masking and racking can be defined.

vs Powder Coating

Choose anodizing when you want a finish that becomes part of the metal, won’t chip like a polymer film, and preserves sharp details and laser marking. It’s also better when you need electrical insulation on the surface without a thick build that can interfere with fits.

vs E-Coating

Choose anodizing when wear resistance and hardness matter, or when you want a metallic look with dyed color options. Anodizing also performs well on aluminum without relying on a deposited paint film that can be damaged at edges and during assembly.

vs Chromium Electroplating

Choose anodizing when you need corrosion protection and surface hardness on aluminum without adding a plated metal layer or risking peeling/flaking from poor adhesion. Anodizing is typically more cost-effective for large surface areas and supports cosmetic dyeing and marking.

vs Physical Vapor Deposition (PVD)

Choose anodizing when you need a cost-effective, high-throughput finish on aluminum with strong corrosion resistance and good cosmetic consistency at scale. PVD is better for thin decorative metallic colors, while anodizing is better for integral protection and dyeing on aluminum.

vs Nickel Electroplating

Choose anodizing when you want a lighter-weight aluminum part with integral corrosion protection and optional color, rather than adding a metallic deposit. Anodizing also avoids potential dimensional buildup associated with thicker plating on threads and precision fits.

Design Considerations

  • Call out anodize type and thickness (e.g., Type II vs Type III/hardcoat) and whether dye/color is required to avoid quote ambiguity
  • Define racking/contact locations and acceptable contact marks on cosmetic faces; add hidden tabs or non-cosmetic areas for clamps
  • Mask critical threads, bearing bores, seal grooves, and mating surfaces; specify which features must remain conductive or uncoated
  • Allow for coating buildup on tight fits and threads; consider post-anodize ream/hone or oversize/undersize features as needed
  • Keep alloy and heat treat consistent across the lot; mixed alloys, welds, and cast/rolled sections can shift color and appearance
  • Specify sealing requirements and performance standards (e.g., MIL-A-8625, salt spray expectations) when corrosion performance is critical