Aluminum Anodizing vs Powder Coating – Difference Between Anodizing and Powder Coating

2021.8.6

Powder coating and anodizing (anodising) are two commonly used coating types to improve the performance and appearance of CNC parts. In this article, we are going to take about the difference between anodizing and powder coating with details.

What is Anodizing?

Anodizing is a surface treatment method that thickens the natural oxide layer on the aluminum surface. The aluminum anodizing process is an electrochemical process, which requires submerge the aluminum parts into an electrolytic bath, and run an electric current through it, the aluminum is used as the anode in the circuit, an oxidation process will occur on the surface of the metal surface. 

The process of anodizing can be summarized as below.

1: Pretreatment in acid or alkali solutions to remove dirt, grease, and impurities. 

2: Etching on the surface to make it rough. Brightened to a smooth surface to receive a coating. 

3: The section to be coated is dipped in the electrolyte, the current is passed through the electrolyte, oxygen formed in the electrolyte deposits on aluminum section, and the oxygen reacts with aluminum to form a thick oxide coating.

What is Powder Coating?

Powder coating is a type of metal surface finishing process that can be used on a wide selection of metal products, in the process, the dry powder will be applied on the surface using a spray gun, which applies a negative electrostatic charge to the powder, makes it attracted to the grounded metal part.

Advantages of Coatings

– Coatings or finishes can improve the corrosion resistance of aluminum parts.

– Coatings can enhance the appearance and look, raw materials from mills are very dull.

– Coatings can protect aluminum parts from wear and tear.

– Coatings can hide the dye marks generated by mill finish, maintain surface smooth and even.

– Coatings can increase the reflectivity of materials, hardness of the material.

Difference Between Anodizing and Powder Coating

1. Process. Anodizing is an electrochemical process, which thickens and strengthens the existing thin natural oxide coating, while powder coating is an electrostatic process that electrostatically charged dry powder is sprayed for coating. 

2. Color choices. Anodising has a very limited choice of colors, matching with the building color scheme is difficult. But powder coating has unlimited colors to choose from, it can match any building color scheme. 

3. Finish. Anodizing is available in clear and satin finishes, powder coating is available in simple matt, satin, and gloss finish to super matt, gloss, and textured finishes. 

4. Color variation. Anodizing shows shade variation between batches, the color formed by powder coating is consistent and uniform, with no shade variation between batches. 

5. Uses. Anodizing can be done only over aluminum products, powder coating can be done on any surface, such as steel, wood, composite, etc. 

6. Repairing & repainting. Anodizing can’t be repaired, dented, or repainted, anodized aluminum products need to be protected by wrapping in the construction stage. Powder-coated parts can be repainted easily, and the product will retain the same color and texture after denting and repainting. 

7. Strength. Anodizing is harder than powder coating. 

8. Wear and abrasion resistance. Anodized components are highly resistant to wear and abrasion, easy to clean and maintain. Powder coating is not wear-resistant and abrasion-resistant as anodizing. 

9. Lifespan. Anodized parts have a longer life than powder-coated objects. 

10. Applications. Anodized aluminum or products are usually used in high traffic areas and applications subjected to continuous wear and tear. Powder-coated products are not usually preferred in heavy traffic areas. 

11. Durability. Anodizing becomes a part of the metal, but powder coating is just a coating. On exposure to external atmospheric conditions like sunlight, moisture and heat, anodized parts never fade or peel off. No effect on any climate changes or heat. Powder-coated parts are vulnerable to external atmospheric conditions and may fade on long exposure to sunlight, crack or peel off on exposure to humidity and moisture. 

12. Chemical resistance. Anodizing is vulnerable to chemical attack, hence to be protected from cement, lime, etc., in the construction stage by wrapping it. Powder coating can resist chemical attacks better than anodizing. Cement and lime have no impact on powder coating. 

13. Price. Anodizing is relatively costly, and a powder coating is cheap.

14. Recycling. Anodized materials can be recycled directly without any coating removal, the recycled product has the same properties as a virgin product, powder coating has to be removed before commencing recycling. 

15. Surface visibility. Weld joints are visible in anodizing, powder coating covers the welded joints.