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Getting Your Parts Anodized (All You Need To Know)

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If the part is made of aluminium or other select materials, manufacturers often finish it off by treating the part’s surface with an electrochemical solution. This process is called anodizing.

Get to know all about this process, its advantages, and considerations to make before applying it to your parts.

 

What is Anodizing?

Anodizing is the process of using electricity and chemicals to coat an aluminium part (or other select metals) in a surface layer of oxide. Oxide is a chemical compound that consists of at least one oxygen atom and some other element.

Anodizing is one of the most durable surface finishes available, hence its popularity. It improves corrosion resistance, enhances part aesthetic, strengthens surface layers, and is relatively inexpensive. It is also low maintenance and an ideal foundation for painting or powder coating.

 

 

There are two main types of anodizing: clear anodizing and colour anodizing.

 

Clear Anodizing

Clear anodizing produces a translucent oxide layer that allows some of the underlying metal material to show through. This type of anodizing is often found in jewelry, kitchen utensils, and engineering components that sustain a natural look.

 

aluminium cnc machined part with clear anodized finish

 

Colour Anodizing

Colour anodizing is the process of adding pigment to an opaque oxide layer either by colour dipping or electrolytic colouring. This type of anodizing is often used on external automotive parts and other products where a decorative finish is desired.

 

what is anodizing: color anodised part

 

How Does Anodizing Work?

To anodize aluminum, the metal is placed in an acidic solution and a current is passed through it. The aluminum oxide that forms on the surface of the metal acts as an insulator, so the current does not flow through the metal itself. This process creates a strong, durable oxide layer that can protect the aluminum from corrosion and wear. It also makes the part appear glossier and more aesthetically pleasing. The colour of the oxide layer depends on the type of acid used in the anodizing process.

Read this step-by-step guide for a more detailed understanding of how parts are anodized.

 

What Materials Can Be Anodized?

Applying an anodized finish to aluminum would lead to a hard and corrosion-resistant aluminum oxide. Iron, on the other hand, would turn to iron oxide (rust), which would just flake off the surface. Therefore steel or any other iron-based metal cannot be anodized.

Anodization is key for all grade of aluminium. Other materials that can undergo this electrochemical process include, titanium, zinc, magnesium tantalum, and niobium.

 

Main Benefits of Anodizing

Understanding the advantages of anodizing will you help you in deciding whether the coating should be used on your part. Below are the main benefits of applying an anodized finish to a metal part.

 

  • Hardens part surface.
  • Provides excellent corrosion and wear resistance.
  • Increases durability.
  • Extends part’s life span.
  • Provides better thermal insulation.
  • Increases dielectric strength.
  • Lends an attractive metallic look to the part.

 

Considerations Before Anodizing

It’s important to emphasize that anodizing doesn’t work on every metal. It’s also less likely to work to its fullest extent if the surface of the part is too rough or if the design of the part is complex. Keep the following considerations in mind before anodizing any of your metal parts:

 

  • Not All Materials Can Be Anodized –Materials like steel will dissolve in the chemical solution and, therefore, can’t be anodized.
  • Change in Dimensions and Tolerances – Geometric dimensions and tolerances may change due to the added coating, so you should account for it in the design process.
  • Matching Colour – Expect that colour matching will never be 100% accurate.
  • Surface Roughness – Surface roughness on the part can negatively impact the overall anodized finish.
  • Out of Reach Areas – A portion of the part surface is likely to not become anodized during the anodizing process. The solution may not reach it, or it may not be completely submerged.

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