Powder coating and its coating technology is a new process and technology that has been rapidly developed in our country for more than ten years. It saves energy and resources, reduces environmental pollution, is simple in process, easy to realize automation, the coating is durable, and the powder is recyclable. Features of reuse. The following summarizes the common problems of powder coating application.
1. Discoloration of paint film
cause:
1. There is residual treatment liquid on the surface of the paint.
2. Excessive baking, or volatile gas in the furnace.
3. Mix powder of other colors during construction.
4. The pigment of the powder itself is not resistant to high temperature or the resin is easy to turn yellow.
Solution:
1. Improve the pre-treatment method.
2. Develop proper baking conditions and purify the baking furnace.
3. Strengthen the cleaning before construction.
4. Replace qualified powder coating.
Second, there are particles on the surface of the coating
cause:
1. The surface of the painted workpiece is not clean
2. Uneven powder supply and poor atomization of the spray gun.
3. The powder is too fine or the powder is damp and agglomerates, causing powder to accumulate in the spray gun.
4. The painting site is not clean or there is powder dripping in the spray chamber.
5. The recycled powder or the powder itself is of poor quality.
Solution:
1. Improve the quality of the workpiece substrate and strengthen the pre-treatment.
2. Adjust the air pressure, check the deflector, and adjust it to the best point.
3. Control the particle size distribution of the powder, keep the powder properly and prevent moisture.
4. Clean up the scene and purify the air.
5. After the recycled powder is sieved, the new powder is mixed for use and the qualified powder is replaced.
Three, shrinkage
cause:
1. There is oil stain on the surface of the workpiece.
2. The compressed air contains water, oil, etc., which causes the powder to be contaminated.
3. Contaminated by dust or other impurities
4. The powder coating itself is polluted
Solution:
1. Strengthen the pre-processing.
2. Strengthen the purification of compressed air before painting.
3. Thoroughly clean up the environment and replace qualified powder.
4. Poor leveling or serious orange peel
cause:
1. The surface of the workpiece is rough.
2. The powder particles are coarse, damp, or the powder leveling itself is poor
3. The curing temperature is too high or low
4. The coating film is too thin or too thick.
5. Poor grounding of the workpiece.
6. Mixing of different powders.
Solution:
1. Improve the finish of the workpiece.
2. Choose high-quality powder with uniform particle size distribution and good leveling and prevent the powder from being damp.
3. Adjust the appropriate curing conditions.
4. Control the powder thickness in 60-80μm.
5. Clean the hanger regularly.
6. Strictly clean up the powder spraying system and site before construction to avoid mixing powders of different types or different manufacturers.
5. Loss of gloss on the coating surface
cause:
1. Poor quality of substrate pretreatment.
2. The baking time is too long or the temperature is too high.
3. There is volatile gas in the furnace.
4. The proportion of recycled powder used is too large.
5. Two powders with different properties are mixed.
6. Poor quality of powder coating.
Solution:
1. Choose a suitable pre-treatment process.
2. Adjust the appropriate curing conditions.
3. Purify the oven.
4. Mix the recycled powder with new powder after filtering, preferably <30%.
5. Thoroughly clean the powder spraying system before changing the powder.
6. Replace the powder with good quality.
Six, the coating film has pores and pinholes
cause:
1. There are pores on the surface of the workpiece.
2. There is treatment residue on the surface of the workpiece, and the degreasing and rust prevention are not thorough.
3. The conductive putty is shaved too thick and not dry.
4. The spray gun is too close to the workpiece, and the construction voltage is too high, causing coating breakdown.
5. There is volatile gas in the drying tunnel.
6. The coating is too thick, or the coating film is not fully cured.
7. The problem of powder coating itself
Solution:
1. Strengthen the processing of the workpiece.
2. Improve the pre-treatment process.
3. Extend the baking time.
4. Adjust the process parameters.
5. Clean the drying tunnel and purify the gas in the furnace.
6. Control the thickness of the coating film to 50-80μm and adjust the curing conditions.
7. Replace qualified powder coating
Seven, the mechanical properties of the coating film are poor, and the coating falls off as a whole
cause:
1. The quality of the substrate is poor and the pretreatment method is improper.
2. Improper baking conditions, incomplete curing or excessive baking.
3. The quality of the powder is poor, or the shelf life has expired.
Solution:
1. Improve pre-processing.
2. Determine the appropriate baking process.
3. Select qualified powders, if overdue, a comprehensive inspection is required.
8. Poor corrosion resistance of the coating film
cause:
1. The coating film is not sufficiently cured.
2. The temperature of the baking oven is uneven and the temperature difference is large.
3. Improper handling of the workpiece.
4. Poor performance of powder coatings
Solution:
1. Adjust the baking conditions according to the performance of the coating.
2. Choose a suitable oven with a temperature difference of ±5°C from top to bottom.
3. Strengthen the pre-treatment to avoid the treatment liquid remaining on the surface of the workpiece.
4. Replace qualified powder coating.
IX. Poor adsorption of powder flying
cause:
1. The electrostatic generator has no high voltage or insufficient high voltage.
2. Poor grounding of the workpiece.
3. The air pressure is too high.
4. The air duct in the recovery device is blocked.
5. Incomplete pretreatment (rust, oil).
6. The problem of powder coating itself
Solution:
1. Check the electrostatic generator and adjust the voltage.
2. Clean the hanger and keep it grounded.
3. Adjust the air pressure.
4. Clean up the recovery device.
5. Strengthen the pre-treatment process.
6. Use qualified powder coatings
10. The powder supply is uneven and the powder spraying amount is sometimes high and sometimes low
cause:
1. The powder tube is partially blocked, and the powder has poor fluidity.
2. Insufficient air pressure and unstable pressure.
3. Oil and water are mixed in the air.
4. The fluidization of the powder feeder is unstable, and the powder feeder is too small.
Solution:
1. Clean up the debris or agglomeration of the powder tube, keep the powder tube unblocked, and adjust the fluidity of the powder coating dry powder
2. Choose the right air compressor.
3. Regularly drain the oil and water in the air compressor.
4. Keep the fluidized bed pressure stable, and add new powder regularly.
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