Factors Affecting the Spraying Quality of Electrostatic Powder Coating Gun

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.

Technology

(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.