Causes of surface defects in electrostatic powder spraying

1. Insufficient gloss of the coating film: the baking time is too long during curing; the temperature is too high; other harmful gases are mixed in the baking; the surface of the workpiece is too rough; the pretreatment method is improperly selected.

 2. Discoloration of the coating film: repeated baking several times; other gases mixed in the oven; excessive baking during curing.

 3. Orange peel on the surface of the coating film: uneven thickness of the sprayed coating; poor powder atomization and powder accumulation in the spray gun; low curing temperature; powder damp, powder particles too thick; poor grounding of the workpiece; excessive baking temperature High; coating film is too thin.

 4. Concave holes in the coating film: improper treatment, unclean degreasing; source of pollution, compressed air degreasing, incomplete dewatering; uneven surface of the workpiece; contamination by dust or other impurities.

  5. Bubbles in the coating film: After the surface treatment of the workpiece, the water is not completely dried, leaving the pre-treatment residual liquid; degreasing and rust removal are not thorough; the bottom volatiles are not cleaned; the workpiece surface has pores; the powder coating is too thick.

6. Uneven coating film: uneven powder spray; too close distance between spray gun and workpiece; unstable high-voltage output.

 7. The impact strength and adhesion of the coating film are poor: the phosphating film is too thick; the curing temperature is too low and the time is too short, so that the curing is incomplete; the bottom metal is not cleaned; the adhesion of the coated workpiece will be reduced after being immersed in water.

  8. Pinholes in the coating film: the air contains foreign matter and residual oil; the voltage of the spray gun is too high, causing the coating to break down; the distance between the spray gun and the workpiece is too close, causing the coating to break down; the coating is too thin; the coating film is not fully cured .

 9. There is a small amount of sand on the surface of the coating film: the spray is blocked or the airflow is not good; the spray gun is not well atomized; there is powder dripping in the powder spraying room; there are other debris contaminating the surface of the workpiece.

 10. Coating peeling: poor surface treatment of the workpiece, incomplete degreasing and rust removal; insufficient output voltage of the high-voltage electrostatic generator; poor grounding of the workpiece; excessive air pressure during powdering;

 11. Uneven powder supply: The powder supply pipe or the powder spray pipe is blocked, and the powder adheres and hardens at the nozzle; the air pressure is insufficient and the pressure is unstable; the air compressor is mixed with oil or water; the fluidization of the powder supply is unstable. The powder feeder has too little powder; the powder supply tube is too long, and the resistance increases when the powder flows.

12. Powder flying and poor adsorption: The electrostatic generator has no high voltage shortage; the workpiece is poorly grounded; the air pressure is too high; the air duct in the recovery device is blocked.

 13. Small amount of powder spraying: insufficient air pressure, insufficient air volume; too high air pressure, too high air ratio in the mixture of powder and flow; moisture and oil mixed in the air space; partial blockage of the spray gun head.

14. The powder spraying pipe is blocked: due to the material of the powder spraying pipe, the powder is easy to adhere to the pipe wall; the output pipe is heated, causing the powder in the pipe to agglomerate; the powder conveying pipe is bent and distorted; the powder is mixed with relatively solid particles.