Anodizing is an electrolytic process that increases the thickness of the natural oxide layer on the surface of a metal. This layer acts as a barrier against corrosion, making the metal more durable. Anodizing can also be used to change the color of the metal.
The most widely used surface treatment process for aluminum is anodic oxidation; the surface can generate an oxide film of several microns to hundreds of microns; compared with the natural oxide film of aluminum alloy, its corrosion resistance, wear resistance, decoration, insulation Performance and heat dissipation have been significantly improved.
Anodizing of aluminum products can usually be divided into three types: sulfuric acid anodizing, chromic acid anodizing, and oxalic acid anodizing. If not specified, it usually refers to sulfuric acid anodizing.
Commonly used materials
Aluminum and aluminum alloys, the common ones are: 2A12, 5052, 6061, 6063, 7075, etc.; in addition, cast aluminum alloys, such as ADC10, ADC12, A356, A380, etc., are also often anodized
Magnesium alloy: mainly used for conductive oxidation/chemical oxidation, the color is white, yellow;
Titanium alloy: Titanium alloy is anodized, and can be made in various colors, such as blue, yellow, green, gold, etc.
Common anodized film thickness:
The film thickness of ordinary anodic oxidation is usually about 10μm; the range is between 5-15μm
The role of ordinary anodizing:
- Protection: Increase surface hardness (HV300) and improve wear resistance
- Decorative: Surface effects of various colors can be generated
- Insulation: The oxide film is non-conductive and can play an insulating role
- It can improve the bonding force between parts and organic coatings
- It can improve the binding force with the inorganic covering layer
Common Anodizing Colors:
Silver, black, bright silver, gray, matte black, bright black, red, purple, yellow, green, gold, rose gold…, almost any color, you can do it!
Choose the color you need through the Pantone color card number!
General process flow
Aluminum workpiece→hanger→degreasing→water washing→alkali etching→water washing→irradiation→water washing→anodizing→water washing→deionized water washing→dyeing or electrolytic coloring→water washing→deionized water washing→sealing→water washing→bottom hanger→drying →drying→quality inspection→packaging→delivery;
Note 1: Various colors of anodic oxidation can be achieved by two methods, namely dyeing and electrolytic coloring; if there is no special instruction, they are all achieved by dyeing; compared with dyeing, the color of electrolytic coloring will be more firm and Wear-resistant, high-temperature resistant (can withstand 400 high temperature plating); while ordinary anodizing, at this high temperature, the problem of color fading will occur.
Note 2: The entire process of ordinary anodizing, the whole process, can be completed in more than 20 minutes; (for higher film thickness requirements, the required time is correspondingly longer); it should be noted that, When doing black anodizing, the whole process will take more than 2 hours, or even 3 hours; therefore, the price of black anodizing in anodizing factories is higher than that of ordinary anodizing;
Note 3: Ordinary anodizing, the usual pre-process is sandblasting or wire drawing; if there is no high finish requirement for the surface of the workpiece, sandblasting can effectively improve the bonding force between the oxide film and the workpiece, making it more firm Wear-resistant; the commonly used sandblasting is quartz sand, which can be divided into automatic sandblasting and manual sandblasting. The sand numbers are: 80#, 100#, 120#, 150#, 180#, 200#, 220#, etc.