1. Paint Film Discoloration
1.1 Causes
1.1.1 Residual treatment liquid on the coated surface.
1.1.2. Over-baking, or the presence of volatile gases in the oven.
1.1.3. Mixing in powder of other colors during application.
1.1.4. The pigment in the powder itself is not heat-resistant, or the resin is prone to yellowing.
1.2 Solutions
1.2.1. Improve pretreatment methods.
1.2.2. Establish appropriate baking conditions and clean the baking oven.
1.2.3. Strengthen pre-application cleaning.
1.2.4. Replace with qualified powder coating.
2. Particles/Nodules on the Coating Surface
2.1 Causes
2.1.1. The surface of the workpiece is not clean.
2.1.2. Uneven powder supply, poor atomization by the spray gun.
2.1.3. Powder that is too fine or powder that has become damp and clumps together, causing powder buildup in the spray gun.
2.1.4. The coating area is not clean or powder is dripping from the spray booth.
2.1.5. Recycled powder or poor-quality powder itself.
2.2 Solutions
2.2.1. Improve the quality of the workpiece substrate and strengthen pretreatment.
2.2.2. Adjust the air pressure, check the air guide, and adjust it to the optimal point.
2.2.3. Control the powder particle size distribution, store the powder properly, and strictly prevent it from getting damp.
2.2.4. Clean the work area and purify the air.
2.2.5. After sieving recycled powder, mix it with new powder for reuse, and replace with qualified powder.
3. Pinholes
3.1 Causes
3.1.1. Oil stains on the workpiece surface.
3.1.2. Water, oil, etc., in the compressed air cause powder contamination. 3.1.3. Contamination by dust or other impurities.
3.1.3. Contamination by the powder coating itself.
3.2 Solutions
3.2.1. Strengthen pretreatment.
3.2.2. Strengthen the purification of compressed air before coating.
3.2.3. Thoroughly clean the environment and replace with qualified powder.
4. Poor leveling or severe orange peel effect
4.1 Causes
4.1.1. Rough workpiece surface.
4.1.2. Coarse powder particles, dampness, or poor powder leveling.
4.1.3. Curing temperature too high or too low.
4.1.4. Coating film too thin or too thick.
4.1.5. Poor grounding of the workpiece.
4.1.6. Mixing of different powders.
4.2 Solutions
4.2.1. Improve workpiece surface finish.
4.2.2. Select high-quality powder with uniform particle size distribution and good leveling properties, and strictly prevent the powder from getting damp.
4.2.3. Adjust suitable curing conditions.
4.2.4. Control the powder thickness to 60-80μm.
4.2.5. Clean the spraying equipment regularly.
4.2.6. Thoroughly clean the powder spraying system and site before application, and avoid mixing powders of different types or from different manufacturers.
5. Loss of Gloss on Coating Surface
5.1 Causes
5.1.1. Poor substrate pretreatment quality.
5.1.2. Excessive baking time or temperature.
5.1.3. Presence of volatile gases in the oven.
5.1.4. Excessive use of recycled powder.
5.1.5. Mixing of two powders with different properties.
5.1.6. Poor quality powder coating.
5.2 Solutions
5.2.1. Select a suitable pretreatment process.
5.2.2. Adjust appropriate curing conditions.
5.2.3. Clean the oven.
5.2.4. After filtering, mix the recycled powder with the new powder, ideally keeping the ratio <30%.
5.2.5. Thoroughly clean the powder spraying system before changing powder.
5.2.6. Replace with high-quality powder.
6. Coating with Pores and Pinholes
6.1 Causes
6.1.1. Pores on the workpiece surface.
6.1.2. Residual treatment liquid on the workpiece surface; incomplete degreasing and rust prevention.
6.1.3. Conductive putty applied too thickly and not fully dried.
6.1.4. Spray gun too close to the workpiece; excessively high application voltage, causing coating breakdown.
6.1.5. Volatile gases are present in the drying tunnel.
6.1.6. The coating is too thick, or the coating film has not been fully cured.
6.1.7. Problems with the powder coating itself.
6.2 Solutions
6.2.1. Improve the processing of the workpiece.
6.2.2. Improve the pretreatment process.
6.2.3. Extend the baking time.
6.2.4. Adjust the process parameters.
6.2.5. Clean the drying tunnel and purify the gas inside the oven.
6.2.6. Control the coating thickness to 50-80μm and adjust the curing conditions.
6.2.7. Replace with qualified powder coating.
7. Poor mechanical properties of the coating film, with the coating peeling off in large pieces
7.1 Causes
7.1.1. Poor substrate quality, improper pretreatment method.
7.1.2. Improper baking conditions, incomplete curing or over-baking. 7.1.3. Poor powder quality or expired powder.
7.2 Solutions
7.2.1. Improve pretreatment.
7.2.2. Determine a suitable baking process.
7.2.3. Use qualified powder; expired powder requires comprehensive inspection.
8. Poor Coating Corrosion Resistance
8.1 Causes
8.1.1. Incomplete curing of the coating.
8.1.2. Uneven oven temperature with large temperature differences.
8.1.3. Improper workpiece preparation.
8.1.4. Poor powder coating performance.
8.2 Solutions
8.2.1. Adjust baking conditions according to coating performance.
8.2.2. Select a suitable oven with a temperature difference of ±5℃.
8.2.3. Strengthen pretreatment to avoid treatment solution residue on the workpiece surface.
8.2.4. Replace with qualified powder coating.
9. Poor Powder Adsorption
9.1 Causes
9.1.1. The electrostatic generator is not generating high voltage or the high voltage is insufficient.
9.1.2. Poor grounding of the workpiece.
9.1.3. Excessive air pressure.
9.1.4. Blockage in the air duct of the recovery device.
9.1.5. Incomplete pretreatment (rust, oil).
9.1.6. Problems with the powder coating itself.
9.2 Solutions
9.2.1. Check the electrostatic generator and adjust the voltage.
9.2.2. Clean the hangers and ensure grounding.
9.2.3. Adjust the air pressure.
9.2.4. Clean the recovery device.
9.2.5. Improve the pretreatment process.
9.2.6. Use qualified powder coatings
10. Uneven powder supply, inconsistent powder spraying
10.1 Causes
10.1.1. Partial blockage in the powder pipe, resulting in poor powder flowability.
10.1.2. Insufficient or unstable air pressure.
10.1.3. Oil or water mixed in the air.
10.1.4. Unstable fluidization in the powder feeder, resulting in insufficient powder supply.
10.2 Solutions
10.2.1. Clean debris or clumps from the powder pipe to ensure unobstructed flow and adjust the dry powder flowability.
10.2.2. Select a suitable air compressor.
10.2.3. Regularly remove oil and water from the air compressor.
10.2.4. Maintain stable fluidized bed air pressure and add fresh powder regularly.
