一. Paint film discoloration
Causes:
1. Residual treatment solution remains on the coating surface.
2. Overbaking, or the presence of volatile gases in the oven.
3. Other colored powders are mixed in during application.
4. The pigment in the powder itself is not heat-resistant, or the resin tends to yellow.
Solutions:
1. Improve the pretreatment methods.
2. Establish appropriate baking conditions and clean the baking oven.
3. Enhance cleaning before construction.4. Replace with qualified powder coatings.
二. There are granular bumps on the coating surface
Causes:
1. The surface of the workpiece being coated is not clean.
2. Uneven powder supply or poor atomization of the spray gun.
3. The powder is too fine or the powder has absorbed moisture and clumped, causing powder to accumulate in the spray gun.
4. The coating site is not clean or there is powder falling inside the spray booth.5. Recovered powder or poor quality of the powder itself.
Solutions:
1. Improve the quality of the workpiece substrate and enhance pre-treatment.
2. Adjust the air pressure, check the flow guide, and set it to the optimal point.
3. Control the powder particle size distribution, store the powder properly, and strictly prevent moisture.
4. Clean the site and purify the air.5. Recycle the powder by sieving and mixing with new powder, and replace with qualified powder.
三. Shrinkage CavitiesCauses:
1. Oil or grease on the surface of the workpiece.
2. Moisture, oil, etc., in the compressed air, causing contamination of the powder.
3. Contamination from dust or other impurities.
4. Pollution present in the powder coating itself.
Solutions:
1. Strengthen pretreatment.
2. Enhance purification of compressed air before coating.
3. Thoroughly clean the environment and replace with qualified powder.
四. Poor leveling or severe orange peelCauses:
1. Rough surface of the workpiece.
2. Coarse powder particles, moisture absorption, or poor leveling performance of the powder itself.
3. Curing temperature too high or too low.
4. Coating film too thin or too thick.
5. Poor grounding of the workpiece.
6. Mixing different powders.
Solutions:
1. Improve the surface finish of the workpiece.
2. Choose high-quality powder with uniform particle size and good leveling, and strictly prevent moisture absorption.
3. Adjust to appropriate curing conditions.
4. Control the powder thickness within 60-80 μm.
5. Regularly clean the hanging fixtures.
6. Thoroughly clean the powder spraying system and site before operation to avoid mixing powders of different types or from different manufacturers.
