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By David | 08 October 2021 | 0 Comments

Black Anodized Aluminum Services-The Definitive Guide For Anodizing

Do you ever receive a batch of black anodized aluminum strips arrived with a ton of scratches, scrapes, edges are not fully deburred and dings? Received black  anodized aluminum channel, the anodized surface are chipped. Super bummed?
How to improve the the quality with no chips and defects? Let our Fiter-auto tell you how to make it out.
Let’s go direct to the 6 contents as below.

contents for anodized aluminum
Chapter 1

What is anodizing aluminum

The process in which aluminum or aluminum alloy products are used as anodes, placed in an electrolyte solution for energization, and an aluminum oxide film is formed on the surface by electrolysis, is called anodizing of aluminum and aluminum alloys. After anodic oxidation treatment, the aluminum surface can form an oxide film of several micrometers-hundreds of micrometers. Check Wikipedia for anodizing.

In summary, there are the following classification methods:
According to the current type, there are: direct current anodizing, alternating current anodizing, and pulse current anodizing that can shorten the production time to the required thickness, the film is thick, uniform and dense, and the corrosion resistance is significantly improved.

According to electrolyte, it is divided into sulfuric acid, oxalic acid, chromic acid, mixed acid and natural color anodizing with organic sulfonic acid solution.

According to the nature of the film, it is divided into: ordinary film, hard film (thick film), porcelain film, bright modification layer, semi-conductor barrier layer and other anodic oxidation.

The application of direct current sulfuric acid anodizing is the most common, because it has anodizing treatment suitable for aluminum and most aluminum alloys; the film layer is thicker, harder and wear-resistant, and better corrosion resistance can be obtained after sealing; The film is colorless and transparent, with strong adsorption capacity and easy to color; the processing voltage is low, and the power consumption is low; the processing process does not need to change the voltage cycle, which is conducive to continuous production and practical operation automation; sulfuric acid is less harmful to humans than chromic acid, and has a wide supply , Low price and other advantages.

It is widely used in aluminum doors and windows and other decorative aluminum materials in the construction industry.

Chapter 2

Process of anodizing aluminum

You may always receive smooth and uniform black anodizing aluminum. Do you know how the anodizing works? Let dive into it.
The main process of anodizing aluminum is as follow:

process flow chart for anodized aluminum

Description: Put the workpiece into the degreasing tank at an operating temperature of 50°C. Be careful not to collide with the tank. When the time is up, gently remove the workpiece and move to the next step.
Purpose: to remove oil stains on the surface of the workpiece.

Alkaline washing 
Description: Use the degreasing agent at an operating temperature of 50°C. Gently place the workpiece in the caustic washing tank.
Purpose: Remove the oxide layer on the surface of the workpiece to expose a pure metal matrix

Description: Use nitric acid, operating temperature is normal temperature, gently put the workpiece into the pickling tank
Purpose: Remove dirt on the surface of the workpiece

Chemical polishing
Description: Use phosphoric acid at an operating temperature of 92°C. Gently put the workpiece hanger into the chemical throwing tank, turn on the timer and rotate it left and right, pay attention to bumping the barrel, gently take out the workpiece and move to the next step when the time is up.
Purpose: chemically polish the surface of the workpiece to increase the gloss and thus determine the gloss after the anode

Description: Use sulfuric acid with an operating temperature of 21°C. The automatic line crane moves the flying target to the anode tank and puts the rack into it
Purpose: Convert the surface of the workpiece into a layer of oxide film, which has protective decorative properties and some other functional characteristics

Description: Use the dye operating temperature 55℃ automatic line crane to move the flying target to the dyeing tank and put the hanger into it. If you are doing black anodized aluminum, then the black dye should be prepared.
Purpose: According to the customer's color requirements to produce bright and beautiful colors

Description: Use the sealing agent operating temperature 95℃ automatic line crane to move the flying target to the sealing slot and put the hanger into it
1 Prevent the appearance of the anodic oxide film from deteriorating.
2.Improve the wear resistance of the anodic oxide film.
3.Maximize the corrosion resistance of the anodic oxide film.
4.Minimize the fading of the dyed oxide film.
5.Improve the corrosion resistance of the anodic oxide film.
6.Improve the electrical insulation performance of the anodic oxide film, especially the insulation in a humid environment

Description: Operating temperature 50℃
Purpose: Dry the moisture on the surface of the workpiece.
Takeaway: operating temperature and timing are keys for a success anodized aluminum.

Chapter 3

Impact factors of  anodized aluminum

Layer of black dye of anodizing aluminum is not shine enough? Want your anodize aluminum looks beautiful and sturdy?
Here you need to know what are the main impact factors that will influence the surface quality of anodized aluminum.
The physical composition and grade of the aluminum material are important factors for the success of the adsorption coloring. Aluminum materials are divided into high-purity aluminum, pure aluminum and alloy aluminum. High-purity aluminum only contains no more than trace amounts (no more than 0.05%, in order) of the affinity metal; the content of the affinity metal of pure aluminum does not exceed 1%. Because aluminum itself is not strong enough to meet various uses, it forms alloys with other metals, mainly magnesium, zinc, manganese, copper, etc. The higher these components in the alloy, the stronger the mechanical abrasion resistance, but the relatively poorer the suitability for decorative coloring.
Anodized aluminum must be selected to ensure that it can still maintain an attractive appearance after anodizing and coloring. This grade of aluminum is specially prepared and specially tested for anodizing and coloring.
The original colors of aluminum and aluminum alloys vary with their purity levels and different ingredients. The color tone of the adsorption color is affected by the original background color.
When the magnesium content is greater than 5%, the anodic oxide film will be dull.
Aluminum without pretreatment cannot be anodized and colored. In fact, controlled surface treatment is a prerequisite for perfect and smooth dyeing. Mechanical and chemical pretreatment determines the final appearance of the metal surface. The purpose of chemical treatment is to remove lipids, oil stains, mixed affinity, soap residues, and natural oxide films on the metal. If these pollutants are not completely removed, they will hinder the formation of oxide film and have a significant adverse effect on dyeing.
Chapter 4

Application of anodized aluminum

Our factory make black anodized aluminum in vary applications. Black anodized aluminum sheet, black anodized aluminum round tubing, square tubing, flat bar,aluminum extrusion,business cards, tags, plate,U channel, aluminum strips ect, widely used in home decoration and industry application.
Our anodized aluminum in very sturdy and good quality.

Chapter 5

Advantages of anodising aluminum

An excellent anodized aluminum in perfect color will have below characters:
- natural metallic anodised finish
-corrosion resistance
-good appearance for decoration
- high resistance value
- high abrasion resistance
- adds a touch of the modern feel
Chapter 6

Our cases study in

We are working on black anodized for more than 10 years. You may face issues that the anodized surface  are chipped  and edges are not fully deburred, just like our customer used to be. Now they come to us, issues solved.

We proved anodized aluminum that exactly as described and delivered on time.
Case 1#  anodized aluminum slatwall

anodized aluminum slatwall
Case 2#  anodized stackable channel
anodized stackable slatwall
Case 3#  anodized aluminum with different colors
anodized aluminum with different colors

Case 4#  golden anodized aluminum round ring
anodizing golden ring

Case 5# other applications
aluminum anodizing cases

Do you want to try one color for your project? Pls contact us via Email:[email protected]



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