Why Anodize and How to measure?

Why Anodize and How to measure?

Anodizing is a highly effective and desirable means of finishing aluminum. Some of the primary advantages of anodizing include:

  • Durability – Most anodized parts experience no wear from handling, installation, usage and maintenance Adhesion – Anodizing is part of the aluminum for total bonding and unmatched adhesion.
  • Color – Anodized parts maintain good color stability when exposed to ultraviolet rays, do not have an applied coating that is subject to chipping or peeling, and have a repeatable coloring process.
  • Quality of original finish – Parts are not subject to marking from the original anodizing process.
  • Maintenance – Mild soap-and-water cleaning usually will restore an anodized profile to its original appearance.
  • Aesthetics – Anodizing offers a large number of gloss and color alternatives, while allowing the metallic appearance of the extruded aluminum to show through.
  • Cost – Anodizing is a very cost-effective value compared to other finishing methods. In addition to low processing and maintenance costs, durability minimizes replacement costs.
  • Environment, health and safety – Anodizing is favorable towards current governmental regulations because it is one of the most environmentally friendly industrial processes and is typically not harmful to human health. An anodized finish is chemically stable, will not decompose, is nontoxic, and is heat-resistant to the melting point of aluminum. Since the anodizing process is a reinforcement of a naturally occurring oxide process, it is non-hazardous and produces no harmful or dangerous by-products. Chemical baths used in the anodizing process often are reclaimed, recycled, and reused.

Anodized aluminum sample, matt finish

How to measure?

The anodizing process parameters have a significant influence on the properties of the oxide formed. If low temperatures and acid concentrations are used, it yields a less porous and harder coating. Higher temperatures and acid content, along with longer immersion times produces softer, more porous coatings. Minor changes to the alloy itself or any of these parameter can significantly affect the coating.

Through various process controls and measurement techniques, Anodizers are able to monitor, control and correct the anodized coating application.  One of the most critical quality controls for anodizing is thickness.  Thickness of anodizing can be measured non-destructively using an eddy current gage or by calculating weight per unit area.  The simplicity of the eddy current method is not only more efficient than the calculation method, but also enable the inspector to verify that adequate anodizing occurs across all surfaces of the part.

Anodization thickness gauge



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