Aluminum Anodizing
Anodizing is a controlled electrochemical process that increases corrosion resistance by thickening the oxide layer naturally present on aluminum and aluminum alloy surfaces. The anodic oxide layer provides electrical insulation and can be dyed in a wide range of colors. These coatings also improve the adhesion of paint primers and adhesives and are an excellent base for decorative finishes.
Mil-A-8625 In accordance with this standard, we apply Type 2 (Class 1, Class 2) and Type 3 (Class 1, Class 2) anodizing.
Sulfuric Acid Anodizing (Type 2)
The sulfuric acid process is the most widely used method. It is applied especially to surfaces that require high corrosion resistance and a decorative appearance. Sulfuric acid anodizing can be applied in a thickness range of 2–25 µm. The total coating thickness forms with approximately 67% penetration into the substrate and 33% growth over the original dimensions of the part. On aluminum and aluminum alloys, the porous structure of sulfuric acid films is particularly advantageous for achieving a colored surface appearance before sealing.
• Class 1 : Non-dyed.
• Class 2 : Dyed.
Base metals to which MIL-A-8625 Type 2 sulfuric acid anodizing can be applied include 1100, 2000, 3000, 5000, 6000 and 7000 series aluminum alloys.
Hard Anodizing (Type 3)
Hard anodizing is used for aluminum alloys exposed to abrasive environments where superior wear resistance and a thicker, harder and more durable surface coating are required. It also offers advantages on aluminum alloy surfaces that require enhanced electrical insulation. Hard anodizing can be applied in thicknesses between 15 and 100 µm. In non-dyed applications, the color of the aluminum oxide depends largely on the alloy of the aluminum material.
• Class 1 : Non-dyed.
• Class 2 : Dyed. (Usually black; other colors are not decorative.)
Base metals to which MIL-A-8625 Type 3 hard anodizing can be applied include 1100, 3000, 5000, 6000 and 7000 series aluminum alloys. It is not preferred for 2000 series aluminum alloys.
Differences Between Type 2 and Type 3 Anodizing
At ELDEM Kaplama we offer two options for this process: Type 2 standard anodizing and Type 3 hard anodizing. Both coatings provide a protective barrier on aluminum and comply with MIL-A-8625. However, there are a few differences to keep in mind before choosing one of them.
Type 2 standard anodizing forms a coating up to 25 microns thick on the aluminum surface. After anodizing and dyeing, porous structures form in the coating layer. Sealing processes are applied to close these pores and improve corrosion resistance. It is the most widely used form of aluminum anodizing. Dyed and non-dyed options are available.
Type 3 hard anodizing forms a coating up to 100 microns thick on the aluminum surface; typically around 50 microns is applied. Hard anodizing is a more durable coating. Dyed and non-dyed options are available. Sealing is not applied when maximum wear resistance is required or when adhesion is needed on an undyed part.
Sealing is required after hard anodizing. After hard anodizing, part surfaces are porous and tacky. Sealing after coating closes the pores and prevents tackiness. Sealing also fills the pores of dyed parts and prevents fading.
Related services: At our facility in Ankara İvedik OSB we also offer chromate conversion (Alodine) coating, sandblasting and fiber laser marking services. You can send the technical drawing of your part via our quote form .
Guides (in Turkish): What is hard anodizing (Type 3) and how does it differ from Type 2? · Black and colored anodizing · How to write a coating note on a technical drawing · Masking in surface finishing
Repeatability
Fully automatic anodizing line
Our coating lines are fully automatically controlled.
Automated control ensures repeatable quality in the coatings we apply to your products.
We meet technical requirements such as repeatable decorative appearance and coating thickness in high-volume production.
Precision
Precise dimensional inspection of parts
We have precision measuring equipment in-house.
For parts with tight tolerances, we take measurements during the coating process to deliver the coating thickness you require.
We apply coatings of the appropriate thickness to your products in a controlled way, in line with your designs.