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What is the principle and process of anodizing during surface treatment of CNC Customized Parts?

2024 - 07 - 16

Anodic oxidation, as the name implies, refers to the process of forming a dense oxide film on the surface of metals (such as aluminum, magnesium, titanium, etc.) by electrochemical methods in an electrolyte solution. In this process, the metal part acts as an anode and is connected to the positive electrode of the power supply, while the cathode of the electrolyte is connected to the negative electrode of the power supply. When the current passes through, the atoms on the metal surface react with the oxygen ions in the electrolyte to form an oxide film.

1. The principle of anodizing aluminum is that in an appropriate electrolyte (such as sulfuric acid, oxalic acid, etc.), the surface of the aluminum reacts with oxygen ions to form a porous aluminum oxide (Al₂O₃) film. This film has extremely high hardness and good wear resistance, which can effectively prevent further oxidation and corrosion of the aluminum. The aluminum oxide film also has good adsorption, which provides conditions for subsequent dyeing, sealing and other treatments.

2. Anodizing process
Surface pretreatment: Before anodizing, the surface of CNC customized parts is cleaned to remove impurities such as oil, dirt and oxide scale to ensure the uniformity and quality of the oxide film. Common pretreatment methods include alkaline washing, acid washing and mechanical polishing.
Anodizing: The pretreated parts are placed in the electrolytic cell and connected to the positive pole of the power supply as an anode. The electrolytic cell is filled with an appropriate amount of electrolyte. Under the action of constant voltage or current, an aluminum oxide film begins to form on the surface of the parts. Parameters such as oxidation time, electrolyte concentration, and temperature will affect the thickness and performance of the oxide film.
Dyeing treatment: For parts that need to be colored, dyeing treatment can be performed after anodizing. The porosity and adsorption of the aluminum oxide film are used to penetrate the dye into the membrane pores to form various colorful oxide films.
Sealing treatment: There are many micropores on the surface of the dyed or undyed oxide film, and sealing treatment is required to improve the corrosion resistance and weather resistance of the film. Common sealing methods include hot water sealing, cold sealing and steam sealing.