Views: 314 Author: Isabella Publish Time: 2018-05-11 Origin: Site
Factors Affecting the Spraying Quality of Electrostatic Powder Coating Gun
Quality impact factors
Powder electrostatic spray gun as a necessary tool for electrostatic spraying, its performance directly determines the final spraying effect. The general spray gun consists of cascade, gun body, nozzle, Powder Hopper and auxiliary air device. A high-quality Cascade (high-voltage module) can generate a stable and long-lasting high-voltage electric field to ensure that the powder particles can carry an effective and sufficient negative charge to ensure reliable adsorption of the workpiece. The gun body and the nozzle need to be made of high quality materials to ensure that the gun has a lighter weight and a longer service life. The intelligent controller and aerodynamic assist device help the gun to provide the powder with reasonable air driving force. Ensure film thickness and penetration into certain difficult-to-spray areas.
The factors that often determine the spray quality are the following: one is a uniform and stable film thickness, and the other is that for a shaped workpiece, the powder can overcome the Faraday cage phenomenon, effectively infiltrate and spray. Therefore, the performance of the spray gun will directly determine the effect of the powder coating. The charging characteristics of the powder and the aerodynamic performance mentioned above will directly affect the final coating quality.
(1) Surface pretreatment. The main method is degreasing and rust removal. The method is the same as pretreatment of liquid paint.
(2) Putty. Scrape the conductive putty according to the degree of defect of the workpiece, dry it with sandpaper, and smooth it to complete the next process.
(3) Protection (also called shelter). If some parts of the workpiece do not require coating, they can be covered with protective glue before preheating to avoid spraying paint.
(4) Warm up. Generally does not need to warm up. If a thicker coating is required, the workpiece can be preheated to 180 to 20°C, which increases the thickness of the coating.
(5) spraying. In the high-voltage electrostatic field, the dust gun is connected to the negative pole, and the workpiece ground (positive pole) constitutes a circuit. The powder is sprayed by the gun with negative charge, and is sprayed on the workpiece according to the principle of anisotropic suction.
(6) Curing. After spraying, the workpiece is heated in a drying chamber at 180-200°C to cure the powder.
(7) Clean up. After the coating is cured, remove the protection and smooth the burr.
(8) Inspection. Check the coating of the workpiece, and if there is any defect such as missing spray, bump, or pinhole, it shall be reworked.
(9) Defect handling. Repairs or re-sprays workpieces that have leaks, pinholes, bumps, bubbles, etc.