Causes and Solutions of Poor Surface Coating of Electrostatic Spraying Powder

       On October 21, 2021, the causes and solutions of the poor surface coating of electrostatic spray powder



   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 not selected properly.



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



  3. Orange peel on the surface of the coating film: the thickness of the sprayed coating is uneven; the degree of powder atomization is not good, and the spray gun has powder accumulation; the curing temperature is low; the powder is damp, and the powder particles are too coarse; the workpiece is poorly grounded; the baking temperature is too high High; the coating film is too thin.



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



  5. Air bubbles appear in the coating film: after the surface of the workpiece is treated, the moisture is not completely dried, leaving pre-treatment residue; degreasing and rust removal are incomplete; the underlying volatiles are not cleaned; the surface of the workpiece 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 pressure output.



  7. Poor impact strength and adhesion of the coating film: the phosphating film is too thick; the curing temperature is too low and the curing 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 soaking in water.



  8. Pinholes in the coating film: there are foreign objects in the air 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. A small amount of sand particles appear on the surface of the coating film: the spray is blocked or the air flow is not good; the spray gun is not well atomized; there is powder dripping in the powder spraying room; other debris contaminates the surface of the workpiece.



  10. The coating falls off: the surface of the workpiece is not well treated, and the degreasing and rust removal is not complete; the output voltage of the high-voltage electrostatic generator is insufficient; the grounding of the workpiece is poor; the air pressure is too high when powdering;



  11. Uneven powder supply: the powder supply pipe or 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 powder of the powder feeder is too small; the powder supply pipe is too long, and the resistance increases when the powder flows.



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



  13. Small amount of powder spraying: insufficient air pressure and insufficient air volume; too high air pressure, the air ratio in the mixture of powder and flow is too high; water vapor and oil stains are mixed in the air; the spray gun head is partially blocked.



  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 disassembled and twisted; the powder is mixed with relatively fine particles of impurities.