Aluminum

Aluminum anodizing forms a controlled oxide layer that improves corrosion resistance, wear, and dyeability, with Type I/II/III options for performance and thickness.

Overview

Aluminum anodizing is an electrolytic surface treatment that converts the outer aluminum into aluminum oxide, creating a hard, corrosion-resistant, electrically insulating finish. The anodic layer can be left natural, sealed for maximum corrosion resistance, or dyed for durable color; Type I (chromic), Type II (sulfuric), and Type III (hardcoat) cover most performance needs.

Choose anodizing for machined or formed aluminum parts that need improved corrosion resistance, better wear on sliding/handling surfaces, cosmetic color control, or electrical isolation without adding a flaking coating. Key tradeoffs: the oxide layer grows from the base material (dimensional change), can build unevenly in deep bores/threads, and can shift shade between alloys/heat treats. Hardcoat increases wear resistance but reduces dye range and can add brittleness at sharp edges.

Common Materials

  • Aluminum 6061
  • Aluminum 7075
  • Aluminum 2024
  • Aluminum 5052
  • Aluminum 6063

Tolerances

±0.001" to ±0.003" (post-anodize critical features with masking or finish machining)

Applications

  • Colored instrument panels and housings
  • Hardcoat wear surfaces on guides and sliders
  • Corrosion-resistant brackets and mounts
  • Electrical isolation on heat sinks and enclosures
  • Consumer electronics cosmetic aluminum shells
  • Valve bodies and manifolds (sealed anodize)

When to Choose Aluminum

Pick aluminum anodizing when the part needs a durable, integral oxide layer for corrosion resistance, wear improvement, or stable cosmetic color at prototype through production volumes. It fits parts where small, predictable dimensional growth is acceptable or can be managed via masking, racking strategy, or post-process finishing. It works best on alloys and geometries that can be cleaned uniformly and fixtured with consistent electrical contact.

vs Titanium

Choose aluminum anodizing when you want predictable protective performance at lower part and processing cost with straightforward thickness control for wear/corrosion. It’s a better fit when you need hardcoat wear properties and consistent cosmetic dye options across many parts. Titanium anodizing is mainly a color/interference finish with different durability and process windows.

vs Magnesium

Choose aluminum anodizing when you need a robust, widely supported anodic coating with strong corrosion resistance and good cosmetic options. Magnesium requires specialized conversion/anodic systems and stricter corrosion management, and many shops won’t run it due to handling and compatibility limits. Aluminum is the safer default for repeatable finishing and supply-chain depth.

vs Zinc

Choose aluminum anodizing when you need a hard, abrasion-resistant, non-flaking oxide layer and aluminum’s strength-to-weight and thermal performance. Zinc parts typically use plating or chromate conversion; those finishes can be softer and more prone to cosmetic damage under handling. Anodizing also supports durable dye color without adding a separate paint film.

vs Niobium

Choose aluminum anodizing when you need functional corrosion/wear performance on structural parts and want broad commercial anodize capacity. Niobium anodizing is commonly used for vivid interference colors, but the base material and processing are niche and costlier. Aluminum offers better availability, larger part capability, and more standardized specs.

vs Tantalum

Choose aluminum anodizing when cost, lead time, and shop availability matter and the environment doesn’t require tantalum’s extreme chemical resistance. Tantalum is typically selected for harsh chemical service rather than cosmetic or general wear/corrosion improvement. Anodized aluminum covers most industrial needs with lower complexity.

Design Considerations

  • Specify anodize type, target thickness range, and sealing requirement; call out color by standard (e.g., black) and acceptable shade variation.
  • Account for dimensional growth: model allowance on tight bores, fits, and precision datums; use masking or post-anodize machining where needed.
  • Avoid sharp external edges; add small chamfers/radii to reduce burn, edge chipping, and thin/anomalous coating at corners (especially hardcoat).
  • Call out thread strategy (mask threads, chase after anodize, or oversize before anodize) and define which threads are functional vs cosmetic.
  • Design with racking in mind: allow a non-cosmetic contact area and identify cosmetic surfaces that must not show rack marks.
  • Group parts by alloy/heat treat and surface condition to reduce color mismatch and quoting risk; note any welding or mixed materials up front.