Hardcoat Anodizing

Almost As Hard As A Diamond

Hardcoat Anodizing, Type III, Military, Aerospace

Hard anodized coatings or hard anodizing (Type III) is similar to standard anodizing (Type II) in as much as it also creates a film of aluminum oxide on the part. It is produced at colder temperatures and provides a surface that is harder, smoother, and more wear and corrosion resistant than standard anodizing - its hardness characteristics are second only to diamonds.

Hardcoat anodizing can also be grown to greater thickness, typically .002 inches or more.

Purple HardcoatHardcoat finishes are typically darker in appearance than standard anodizing depending on the coating, thickness and alloy. They tend to have a bronze/olive shade from processing. A variety of colors are available on thinner coatings. Heavier coatings can be dyed black and some darker shades of color.

Note: A crucial issue for designers to understand is that aluminum from the substrate is consumed in building the anodized coating. A rule of thumb is 50-50 penetration vs. build: about one thousandth of an inch of aluminum is consumed in building a coating thickness of two thousandths. This is even more pronounced on inside threads of parts. We highly recommend that you consult with our sales or process team prior to anodizing your parts if there are critical tolerances.

Benefits of Hardcoat Anodizing:

  • Wear Resistance
  • Corrosion Resistance
  • Appearance
Understanding and Specifying Anodizing

Anodizing is perhaps the most common specified finish for aluminum components. We receive many questions from manufacturers related to how the process works. With the permission of Joseph Osborne we provide this excellent resource on understanding and specifying anodizing.

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