Aluminum Alloy Sheet & Strip for Anodizing

What is Anodizing?

Anodizing is an electrochemical process that converts the aluminum surface into a durable, corrosion-resistant, and aesthetically pleasing aluminum oxide finish. The oxide layer is integral to the aluminum substrate, so it won't peel or chip like paint. It's used to:

Increase corrosion resistance

Improve wear resistance

Provide an electrically insulating layer

Create a decorative finish (can be dyed in a variety of colors)

Improve adhesion for paints and adhesives

These products are used for electronic appearance parts(such as the ipad shell),decoration,adornment and other industries.

Product Features

Better surface quality,free of scratch,dotted injury,black silk, oil mark, roll marks, bubbles or other defects.

Exquisite surface texture,Exquisite and uniform board after oxidation, good effect of oxidation

Good shape and high flatness.

Key Factors for Choosing Aluminum Alloys for Anodizing

Alloy Composition: Certain alloying elements can interfere with the anodizing process or result in a less desirable finish.

Surface Quality: The surface finish of the aluminum sheet or strip will directly affect the final appearance of the anodized part. Scratches, dents, or other imperfections will be visible after anodizing.

Grain Structure: A fine, uniform grain structure will produce a smoother and more consistent anodized finish.

Heat Treatment: The temper (heat treatment) of the aluminum can affect its anodizing response.

End-Use Requirements: The specific requirements of the application (corrosion resistance, wear resistance, color, etc.) will influence the alloy selection.

Aluminum Alloys Best Suited for Anodizing

Generally, alloys with lower alloy content (especially copper) anodize better. Here's a breakdown:

5005 Aluminum: Excellent anodizing response. Produces a clear, bright, and uniform finish with excellent color match. Widely used for architectural applications, trim, and decorative parts. Is one of the best choices when aesthetics are paramount.

5052 Aluminum: Good anodizing response and high strength. Offers a good balance of strength, corrosion resistance, and anodizing quality. Used for marine applications, tanks, and other structural components. Typically provides a matte appearance.

5454 Aluminum: Very good corrosion resistance. Is similar to 5052 but will give a higher strength.

5754 Aluminum: Very good corrosion resistance. Is similar to 5052 but will give a higher strength.

6061 Aluminum: Good anodizing response, but can be more challenging than 5005. The silicon content can result in a slightly darker or grayish finish. Common for structural components, automotive parts, and aerospace applications. Needs careful process control for consistent color.

6063 Aluminum: Very Good anodizing response. Excellent for extrusions and parts requiring a smooth, bright finish. Commonly used for architectural extrusions, window frames, and lighting fixtures. Is generally slightly better than 6061 regarding anodizing quality.

1100 Aluminum: Good anodizing response, very formable. Commercially pure aluminum. Softer and weaker than other alloys but offers excellent corrosion resistance. Typically a matte silver finish.

3003 Aluminum: Fair to Good anodizing response. Good corrosion resistance and moderate strength. Can be dyed, but the finish may not be as bright or uniform as with 5005 or 6063. Can have a slight golden hue.

5657 Aluminum: Specifically designed for bright anodizing. Used for decorative trim and automotive brightwork.

Alloys to Avoid (or Use with Caution):

2xxx Series (Aluminum-Copper Alloys): The high copper content makes these alloys very difficult to anodize. The resulting finish is often porous, weak, and discolored. 2024 is a common example.

7xxx Series (Aluminum-Zinc Alloys): Also difficult to anodize due to the zinc content. Can result in a powdery or uneven finish. 7075 is a common example.

Detailed Considerations for Each Alloy

5005:

Anodizing Quality: Excellent. Clear, bright, and uniform finish.

Best Uses: Architectural applications, decorative trim, parts requiring excellent color match.

Limitations: Lower strength than some other alloys.
6063:

Anodizing Quality: Very Good. Smooth, bright finish.

Best Uses: Architectural extrusions, window frames, lighting fixtures.

Limitations: Lower strength than 6061.

6061:

Anodizing Quality: Good. Can be more challenging than 5005 or 6063 due to silicon content. Requires careful process control.

Best Uses: Structural components, automotive parts, aerospace applications.

Limitations: Can result in a slightly darker or grayish finish.

3003:

Anodizing Quality: Fair to Good.

Best Uses: General-purpose applications where corrosion resistance is important.

Limitations: The finish may not be as bright or uniform as with other alloys.

5052:

Anodizing Quality: Good

Best Uses: Marine Applications.

Limitations: The finish may not be as bright or uniform as with other alloys.

1100:

Anodizing Quality: Good

Best Uses: General purpose applications where good ductility is needed.

Limitations: The finish may not be as bright or uniform as with other alloys.

Surface Preparation is Key!

Even with the right alloy, proper surface preparation is crucial for a high-quality anodized finish. Steps may include:

Cleaning: Removing dirt, oil, and other contaminants.

Etching: Creating a uniform surface texture.

Bright Dipping: Chemical or electrochemical polishing to create a bright, reflective surface (for bright anodizing).

Deoxidizing: Removing any existing oxide layer.

Anodizing Processes

Sulfuric Acid Anodizing (Type II): The most common type of anodizing. Provides a good balance of corrosion resistance, wear resistance, and aesthetic appeal.

Hard Anodizing (Type III): Creates a thicker and harder oxide layer for superior wear resistance. Often used for components subject to high levels of abrasion.
Chromic Acid Anodizing (Type I): Primarily used in aerospace applications. Provides excellent corrosion resistance, especially in salt spray environments. Results in a thinner oxide layer than sulfuric acid anodizing.

Considerations When Specifying Aluminum for Anodizing

Specify the Alloy and Temper: Clearly state the desired aluminum alloy and temper (e.g., 5005-H34, 6061-T6).

Specify the Anodizing Type: Indicate the type of anodizing required (Type II, Type III, etc.).

Specify the Oxide Layer Thickness: Provide a thickness range for the oxide layer (e.g., 0.0002 to 0.0007 inches).

Specify the Color (if applicable): If you want a colored anodized finish, specify the desired color.

Specify Surface Finish Requirements: Indicate any specific surface finish requirements (e.g., smooth, matte, bright).

Provide Drawings or Specifications: Include detailed drawings or specifications for the part, including dimensions, tolerances, and any special requirements.

Finding Suppliers

Aluminum Distributors: Companies that sell aluminum sheet, strip, and other forms.

Anodizing Service Providers: Companies that specialize in anodizing aluminum parts.

Integrated Suppliers: Some suppliers offer both aluminum materials and anodizing services.

In summary, selecting the right aluminum alloy is essential for achieving a high-quality anodized finish. 5005 is often considered the best overall choice for anodizing due to its excellent anodizing response and consistent color match. 6063 is an excellent choice for extrusions. However, 6061 is a strong and commonly available alternative when 5005 isn't specified. Proper surface preparation and control of the anodizing process are also critical for success. Remember to clearly specify your requirements to both your aluminum supplier and your anodizing service provider to ensure that you get the desired results.