Anodizing is a surface treatment process that employs electrochemistry to create a layer of aluminum oxide (Al2O3) film on the surface of aluminum and aluminum alloys. Through the process of anodic oxidation, the material’s surface state and performance can be altered, resulting in improved corrosion resistance, enhanced wear resistance and hardness, and protection of the metal surface.
Non-ferrous metals or their alloys, such as aluminum, magnesium, and their alloys, can undergo anodization. This method finds extensive use in various applications, including mechanical parts, aircraft and automobile components, precision instruments and radio equipment, as well as everyday items and architectural decoration.
Types of Anodizing
| Type II Anodizing | Type III Anodizing | |
| Materials | Aluminum | Aluminum |
| Color | Clear, black, blue, gold, grey, red, etc. | Clear, black |
| Texture | Smooth, matte finish. | Smooth, matte finish. |
| Thickness | 1.8 μm to 25 μm (0.00007″) | > 0.001″ |
| Applications | Consumer goods, aircraft components, architectural parts, kitchenware | Parts subject to high and low temperatures, chemical exposure, or wear |
Design Considerations
>Anodizing imparts insulative properties to parts, resulting in poor electrical conductivity of anodized components.
>To prevent local overheating and burning caused by current concentration, all edges and corners on the workpiece should be rounded with a radius of no less than 0.5 mm, and the presence of burrs is not permitted.
>While hard anodic oxidation treatment can make the surfaces of rough workpieces smoother, those with an already extremely smooth finish may experience a slight loss of smoothness.
>During the hard anodizing process, the workpiece must withstand high voltage and current. It is crucial to design special fixtures to maintain good conductive contact, as the workpiece may otherwise experience breakdown or burning of its contact parts.
