A protective surface with an attractive finish is buyers’ only requirement when purchasing aluminum casting parts. That’s why this article will focus on the 2 most popular surface finishing processes of aluminum castings: anodizing and powder coating. If you don’t know what to choose, we will help you understand them or make the right choice.
What is Anodizing?
Aluminum castings always have a thin layer of natural oxide on their surface. This layer has become passive, and when exposed to the air, it does not react with the surrounding environment. Also, this thin layer protects the rest of the metal from the elements.
Anodizing thickens this thin oxide layer, so it is essentially a surface treatment for cast aluminum parts. In this process, the aluminum foundry uses aluminum pieces, such as a cast part, add them to an electrolytic bath and let the electric current flow through them.
In this case, they use aluminum as an anode, which causes the surface of the aluminum casting to oxidize. This process will create a thicker oxide layer on the natural thin layer.
By thickening the oxide layer, the properties of the naturally formed oxide layer are increased. These properties include wear and corrosion resistance, improved heat dissipation, and better adhesion of glue and primer. The final surface is also ideal for the addition of colorants. However, these chemicals can also be reused in the electrolytic bath for future anodizing projects.
What is Powder Coating?
Powder coating is also a finishing process applied to a wide range of cast aluminum products. The results of this process are excellent, and you will see a protective and decorative layer on the surface of the treated product.
As the name implies, this is a dry application process. No solvents are used here, making powder coating an environmentally friendly approach.
In this process, the aluminum parts are first cleaned thoroughly, and then the powder is applied with a spray gun. The gun creates a negative electrostatic charge on the powder, which is attracted to the grounded aluminum part. The aluminum casting is then cured in an oven, and the powder remains attached to the object. After drying, the powder layer turns into a uniform and solid layer.
The result is very stunning and durable. You can create thick layers and a wide variety of colors and textures.
Let’s find out the quick differences between the two.
Anodizing vs. Powder Coating
Mention below is the direct comparison between the 2 famous surface finishing methods of aluminum castings.
|
Anodizing |
Powder Coating |
| It can’t get a thick layer. Only slight changes will be observed on the cast aluminum part’s surface. | With this method, it is difficult to achieve a thin layer. However, it is best to obtain thick layers. . |
| You will observe a wide variety of metallic colors, with fine finishes. | Powder coating offers striking colors range and textures. |
| Anodizing is eco-friendly if the electrolyte recycling is done properly. | Since no solvents are used in this process, so, powder coating is more eco-friendly. |
| Excellent resistance against wear, scratch, and corrosion. | They show maximum resistance against corrosion if the surface is uniform and undamaged. Also, it shows great resistance compared to anodizing. |
| The process shows resistance against color fading until it is exposed to a specific UV light unit. | The process shows great resistance against color fading even in the presence of UV light. |
| With this process, the aluminum casting surface becomes electrically non-conductive. | Due to the thick layer, the electrical conductivity doesn’t show as good results as bare aluminum. |
| The process will be expensive | Compared to anodizing, it is cost-effective. |
Which Surface Finish Should You Choose?
The surface finish depends on how the application of cast aluminum takes place. Whether you choose anodizing or powder coating, both are environmentally friendly for the surface treatment of aluminum parts. However, both processes have exceptions depending on your needs.
Anodizing offers tight dimensional margins, excellent corrosion and wear resistance, and also gives your castings an attractive metallic appearance. So, if you need heat dissipation in your aluminum casting, or if you are going to subject it to glue or primer application, this process is preferable.
Choose powder coating if you are looking for striking colors or unique textures that can withstand the elements even after exposure. However, compared to anodizing, it offers good protection while remaining affordable.
Any inquiry on aluminum casting on anodizing or powder coating finish, pls contact our aluminum casting company!