There are two common coating types, powder coating and anodizing, which are mainly used to improve the performance and beautify the appearance of CNC parts. Here, we will discuss the main differences between them.
What is anodizing?
Anodizing is a finishing process in surface treatment. It can thicken the natural oxide layer on the surface of aluminum. In fact, the anodizing process of aluminum is an electrochemical process. Aluminum parts need to be immersed in the electrolytic cell, and the current runs in the electrolytic cell. Aluminum acts as an anode in the circuit, then the surface of the metal will undergo the oxidation process.
The whole process of anodizing can be summarized as follows.
1: It is treated in acid or alkali solution to remove dirt, grease and impurities.
2: Etch the surface to make it rough. Brighten to a smooth surface to obtain a coating.
3: Put the parts to be coated into the electrolyte, the current passes through the electrolyte, the oxygen formed in the electrolyte will be deposited on the surface of aluminum parts, and the reaction between oxygen and aluminum will get a thick oxide coating.
What is powder coating?
Powder coating is also a process of CNC surface finish. It can be used for surface treatment of a variety of metal products. Dry powder is usually sprayed on the surface with a spray gun, which applies a negative electrostatic charge to the powder to attract it to grounded metal parts.
Advantages of coatings
the coating can improve the corrosion resistance of metal parts.
the coating improves the appearance.
the coating can reduce external wear of aluminum parts.
the coating can cover the dyeing marks generated during processing and obtain a smooth and uniform surface.
the coating can improve the reflectivity and hardness of the material.
Difference between anodic oxidation and powder coating
1. The process of CNC machining precision is different. Anodic oxidation is an electrochemical process, which can enhance and thicken the existing natural oxide coating, while powder coating is an electrostatic process, that is, electrostatic charged dry powder is sprayed for coating.
2. Color selection. There are few color choices for anodizing, so it is difficult to match with the building color scheme. However, powder coating has a variety of colors to choose from, and it has a scheme that can match any building color matching.
3. Finish. Anodizing has transparent and satin finishes.Powder coating can also get simple matte, satin and gloss finishes, as well as super matte, gloss and texture finishes.
4. Color change. Anodizing shows changes in chromaticity between batches, which is difficult to be completely consistent. The powder coating can form a consistent and uniform color without chromaticity change between batches.
5. Applied materials. Anodizing can only treat the surface of aluminum products, and powder coating can be carried out on the surface of any variety of materials, such as steel, wood, composite materials, etc.
6. Repair and repaint. It is very difficult to repair and repaint anodic oxidation. Anodic alumina products need to be protected by wrapping at the construction stage. Powder coated parts are easier to repaint, and the treated products can maintain the same color and texture.
7. Strength. The powder coating is not hard than anodized . Therefore, anodized components have more wear resistance, longer life cycle and easy cleaning and maintenance. Powder coating is not as wear-resistant and wear-resistant as anodizing, and its life cycle is short.
8. Application. In areas with heavy traffic and applications with continuous wear, anodized aluminum products will be the first. Instead of powder coated products.
9. Durability. The anodized surface has become part of the metal, but the powder coating is only a covering applied to the outside of the CNC precision parts. When exposed to external atmospheric conditions such as sunlight, humidity and high temperature, anodized parts will not fade or fall off. The powder coating will crack or peel without affecting any climate change or heat.
10. Chemical resistance. For chemical attack, such as cement or lime, powder coating performs better than anodizing.
11. Price. The cost of anodizing is higher than that of powder coating.
12. Recycling. Anodized materials can be recycled directly, while powder coatings must be removed before recycling.
13. Visibility of Surface. Welded joints can still be seen on anodized parts. The powder coating does not see the welded joint.