Aluminum Anodizing: All you need to know in 2023

Aluminum Anodizing: All you need to know in 2023


Why aluminum anodizing is needed?

For aluminum parts manufacturers, aluminum parts products must take into account both excellent mechanical properties and aesthetic design, so aluminum anodizing is a good choice for parts processing.

Because the metal components are subjected to anodizing aluminum treatment, the oxide film formed on the surface of the machined parts has good protection, decoration, and other characteristics.

Therefore, the technology of aluminum anodizing is widely used in aviation, electrical appliances, electronics, machinery manufacturing, and the light industry.

An aluminum anodizing part
An aluminum anodizing part

Aluminum Anodizing Process

In order to obtain an artificial film that is firmly bonded to the substrate, meets the requirements of color and thickness, and has the best corrosion-resistant function, wear resistance, weather resistance, and other good properties.

First of all, surface treatment and degreasing (aluminum and products, there will be dirt and defects on the surface to varying degrees). Therefore, before treatment, the surface should be cleaned as necessary to expose the pure metal matrix to facilitate smooth oxidation and coloring.

The second is the process of surface cleaning in sodium hydroxide solution. It is used as a supplementary treatment after degreasing by the degreasing method, so as to further clean up the oily dirt attached to the surface, which is conducive to the formation of the anode film and obtains a higher quality film layer.

Finally, a metal or alloy product is used as an anode, and an oxide film is formed on the surface by electrolysis.

Once anodizing begins, a positive charge is transferred to the aluminum, while a negative charge is applied to the electrode plates in the electrolytic solution.

Aluminum anodizing parts

Normally, the current will force positive ions to be attracted to the negatively charged ground electrode plate, and negative ions will be attracted to the aluminum metal where the positive anode is located.

Of course, there is only one purpose for this, and that is to ensure that the electrochemical reaction can open all the gaps on the surface of the aluminum metal, so as to ensure the safe leakage of + ions. This is like a uniform geometric pattern, the pores have penetrated into every substrate of the aluminum metal.

At this time, the combination of negatively charged ions and the aluminum surface has formed a thick barrier layer. This phenomenon is called the surface layer in the process of aluminum anodizing, and the purpose is also to ensure that the parts have a lay.

Aluminum Anodizing Coloring

Anodizing coloring is one of the most common processes in aluminum oxidation treatment. It can bring excellent acid to create decoration functions for aluminum products. So what should be paid attention to in the process of aluminum anodizing coloring and before and after?

Cleaning After Coloring

If the surface of the aluminum parts is not cleaned, the residual color paste will affect the aluminum products.

Cleaning Before Coloring

Since the anodizing treatment tank needs to be fully cleaned after taking it out, especially the gaps in the aluminum components.

Otherwise, residual acid and alkali will gradually flow out in the coloring process. So that the pH of the coloring solvent exceeds the conventional category, and even rust and oxidation will appear white.

Aluminum Parts Can Not be Stacked During Coloring

During the coloring process, the aluminum parts cannot be superimposed and must be placed in parallel, otherwise, the yin and yang surfaces will be generated due to the occlusion of the superimposed position.

Anodizing coloring parts

Timely Coloring After Anodizing

Aluminum parts should be colored in time after anodizing; If the aluminum parts are exposed to the air for too long after anodizing, the film gap will become smaller, and it may be stained with dirt, resulting in inconvenient coloring.

If the coloring tank is too small, the aluminum products to be colored should be immersed in a clean water body when coloring in batches.

In order to ensure that metal products can have better performance and appearance after anodization, users first need to do two things: washing and cleaning.

This process scrubs the metal surfaces of dust, grime, and other residues before placing them in the electrolytic bath. The purpose of this practice is to add a conductive coating containing positive and negative ions to the metal.

Types Of Aluminum Anodizing

  • Anodized Type 1: This process is the simplest of the anodizing processes. The operator simply uses butyric acid to form a thin, stretchable anodized layer on the aluminum metal part.
  • Anodized Type II: The specific difference between anodizing type II and anodizing type I is that anodizing type II does not use butyric acid, but uses sulfuric acid to process metal parts to form a thicker protective film. This process will not only be superior to anodizing type 1 in corrosion resistance but also improve the aesthetics of the part surface.
  • Anodized Type III: Anodized Type III uses sulfuric acid as the surface treatment, and the process takes a long time, so it can increase the thickness of the oxide layer of the metal parts and achieve better corrosion resistance.
  • Anodized Type IV/Chemical Film: Anodizing type IV is also called chemical film or Alodine.

For parts manufacturers, sulfuric acid is generally used for anodizing. Part manufacturers can choose from different anodizing aluminum methods according to the wishes of their customers.

The Benefits Of Anodizing Aluminum Parts

  • Anodized aluminum parts can improve the corrosion resistance of the component and prolong the service life of the workpiece.
  • The most in-depth analysis of the benefits of anodized aluminum is its excellent workpiece surface protection function. Aluminum parts are easily affected by the natural climate, which can cause corrosion.
  • Anodizing, on the other hand, creates a thick protective film on aluminum products. The anodizing process can increase the aesthetics, and durability of metal components.
  • Anodizing used in natural environments today is higher than metal parts used in non-natural environments.
  • Anodized for improved wear resistance of aluminum parts.
  • Aluminum parts are particularly susceptible to scratches and wear, and anodized aluminum products have a very hard surface, with an aluminum oxide film hardness up to HV300. The abrasion resistance is improved, and it is not easy to scratch.

Anodized Aluminum for Improved Performance and Appearance of Aluminum Parts

Regarding the anodizing process, the performance and appearance of the processed aluminum parts are the focus of many customers. Anodizing can improve the appearance and performance of the parts, and can make glue and paint primer surfaces have excellent adhesion.

Of course, starting from the appearance of aluminum parts, aluminum anodizing technology will produce an anodized film on the external of the aluminum products, making the painting more uniform and beautiful.

anodizing parts

After the metal parts are subjected to aluminum anodizing, the quality of the external protective film can be judged by tests such as friction, electrical conductivity, and electric shock.

At present, the process of the anodizing process still continues the tradition, including degreasing, water washing, anode reaction, water washing, sealing, and finally high-temperature baking.

Anodizing can be applied not only to aluminum but also to other metals such as zinc, magnesium, and titanium.

One thing that is really hard to k

Anodized Aluminum Parts for Easy Recycling

The advantage of aluminum anodizing is that it is easy to recycle. Metal parts are regularly reported for loss, depreciation, and recycling, which are of great concern to parts manufacturers.

Applications Of Aluminum Anodizing

Metal aluminum is a material that is often used in industrial production, daily life, public facilities, and aviation. Aluminum is strong, lightweight, and has good plasticity.

After anodizing, aluminum metal parts can be widely used in various fields, such as aviation, consumer goods, sports equipment, electronic products, and large-scale amusement parks.

At present, the hardness of metal parts that have undergone anodizing type III / anodizing type II operations can already meet the actual demands of different industries.


Anodizing technology is an important surface treatment process in the production of aluminum machining parts. In recent years, with the development of modern industry, the improvement of people’s living standards, and the enhancement of environmental protection awareness, aluminum, and its alloys will play an increasingly important role in people’s daily production and life.

Therefore, the requirements for aluminum anodizing are getting higher and higher, and the functional requirements are becoming more and more diverse.

In the production practice, it is necessary to observe, analyze and summarize many factors affecting the performance of the anodic oxide film for a long time, and master the method of improving the performance of the anodic oxide film, so as to provide a guarantee for obtaining satisfactory product quality.

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