What are the surface treatment processes after cabinet sheet metal processing?

The surface treatment processes after cabinet sheet metal processing mainly include the following:

phosphating

Principle: Phosphating is a process of chemical and electrochemical reaction to form phosphate chemical conversion film. Put the sheet metal part into an acidic solution containing dihydrogen phosphate, and a chemical reaction occurs on the metal surface to form an insoluble phosphate protective film.

Function: This phosphating film can significantly improve the adhesion between the cabinet surface and the coating, so that the subsequent spraying, baking and other processes can be better carried out. At the same time, the phosphating film itself has a certain anti-rust ability, which can provide preliminary corrosion protection for the cabinet. For example, for some computer operating cabinets used in high relative humidity environment, the surface after phosphating treatment can effectively delay the rusting time.

Process parameters: The temperature of phosphating solution is usually controlled at 50-70℃, and the treatment time is about 3-15 minutes. The specific parameters should be adjusted according to the formula of phosphating solution and the material of sheet metal parts.

electrostatic coating

Principle: Using electrostatic adsorption, the powder coating is evenly adsorbed on the surface of the cabinet. A high voltage is applied between the spray gun and the workpiece, so that the powder coating sprayed by the spray gun is charged, and the workpiece is grounded to form an electric field. Under the action of electric field force, charged powder coatings fly to and adsorb on the surface of the workpiece.

Advantages: This process can obtain a uniform and thick coating, and the coating thickness can generally be controlled at 60-120μm m.. Moreover, electrostatic spraying has high efficiency and can quickly complete large-area spraying operation. Compared with traditional liquid coatings, powder coatings contain no solvent and are more environmentally friendly.

Precautions: Before spraying, ensure that the surface of the workpiece is clean and dry, and free of oil and dust. At the same time, the humidity and temperature of the spraying environment will also affect the spraying effect. Generally, it is recommended that the environmental humidity be below 60% and the temperature be between 15-30℃.

Baking paint treatment

Process: Firstly, the surface of sheet metal parts is pretreated (such as degreasing, derusting, etc.), then painted with primer and baked in spray booth. In spray booth, the solvent in the paint is volatilized by heating, and the resin is solidified to form a hard paint film. After the primer is cured, the topcoat may be sprayed and baked to obtain a better appearance and protective effect.

Advantages: the surface of the cabinet after baking paint has high gloss and hardness, which can effectively resist scratches and wear. For example, in the front panel of computer cabinets that need to be operated frequently, the surface after baking paint treatment can maintain a good appearance for a long time.

Parameter control: the temperature and time of baking paint are the key parameters. Different paints have different baking requirements. Generally, the baking temperature of primer is 150-180℃ for 20-30 minutes. The baking temperature of topcoat may be 160-200℃ for 30-40 minutes.

Electroplating treatment

Principle: A layer of metal (such as zinc, nickel, chromium, etc.) is deposited on the surface of sheet metal by electrolysis. The cabinet is used as the cathode, and the metal salt solution is used as the electrolyte. Under the action of direct current, the metal ions in the solution are reduced and deposited on the surface of the cathode to form an electroplating layer.

Function: Electroplated coating can provide good decoration and protection for the cabinet. For example, galvanized coating can play a good role in rust prevention of cabinets, while chrome coating can make the cabinet surface have bright metallic luster, which is often used for cabinet parts with high appearance requirements.

Thickness requirements: The thickness of electroplating layer depends on different application requirements, for example, the thickness of galvanized layer for general industry is about 8-12μm, and the thickness of decorative chromium plating layer is about 0.2-0.5 μ m..

Anodizing treatment (for aluminum cabinets)

Process: Anodizing is a common surface treatment method for aluminum computer operating cabinets. An aluminum workpiece is used as an anode, which is put into electrolyte (usually sulfuric acid, oxalic acid and other solutions) and electrified with direct current to form an oxide film on the surface of the workpiece.

Features: Anodized oxide film is porous, and different colors can be obtained by subsequent treatment such as dyeing. At the same time, the hardness of oxide film is high, which can improve the wear resistance and corrosion resistance of aluminum cabinet. For example, in some computer cabinets that need personalized appearance, anodizing dyeing can meet different design requirements.

Film thickness control: The thickness of oxide film is generally about 5-20μm, and the specific thickness can be controlled by adjusting parameters such as electrolysis time and current density according to actual needs.