Powder coating manufacturers and companies using powder coatings have been constantly exploring powder coating coating technology. Powder coating and its coating technology is a new process and new technology that has developed rapidly in my country for more than ten years. It has the advantages of saving energy and resources, reducing environmental pollution, simple process, easy automation, durable coating, and recyclable powder. The characteristics of reuse, the following summarizes the common problems of powder coating coating.
1. Paint film discoloration
Causes: 1. There is residual treatment liquid on the surface of the coating; 2. Excessive baking, or volatile gas in the furnace; 3. Powders of other colors are mixed in during construction; 4. The pigments of the powder coating itself are not resistant to high temperature or The resin is prone to yellowing.
Solutions: 1. Improve the pre-treatment method; 2. Formulate appropriate baking conditions and purify the baking furnace; 3. Strengthen the cleaning before construction; 4. Replace qualified powder coatings.
2. There are pimples on the surface of the coating film
Causes: 1. The surface of the workpiece to be coated is not clean; 2. The powder supply is uneven, and the atomization of the spray gun is not good; 3. The powder is too fine or the powder is damp and agglomerated, causing the spray gun to accumulate powder; 4. The coating site is not clean or sprayed There is powder dripping in the room; 5. The quality of recycled powder or powder coating itself is poor.
Solutions: 1. Improve the quality of the workpiece substrate and strengthen 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 site , to purify the air; 5. After the recycled powder is sieved, mix it with new powder, and replace the qualified powder.
3. Shrinkage cavity
Causes: 1. There is oil on the surface of the workpiece; 2. The compressed air contains water, oil, etc., causing the powder to be polluted; 3. Contaminated by dust or other impurities; 4. The powder coating itself is polluted
Solutions: 1. Strengthen pre-treatment; 2. Strengthen the purification of compressed air before painting; 3. Thoroughly clean up the environment and replace qualified powder.
4. Poor leveling or severe orange peel
Causes: 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 too low; 4. The coating film is too thin or too thick; 5. The workpiece is not well grounded; 6. . Mixing of different powders.
Solution: 1. Improve the smoothness of the workpiece; 2. Choose high-quality powder with uniform particle size distribution and good leveling and prevent the powder from getting wet; 3. Adjust suitable curing conditions; 4. Control the thickness of the powder at 60-80 μm; 5. Regularly Clean up the hangers; 6. Strictly clean the powder spraying system and site before construction, and avoid mixing powders of different types or different manufacturers.
5. Loss of gloss on the surface of the coating film
Causes: 1. Poor pre-treatment quality of the substrate; 2. Too long baking time or too high temperature; 3. Volatile gas in the furnace; 4. Too large proportion of recycled powder; 5. Two different types of powder Mixed; 6. The quality of the powder coating is poor.
Solution: 1. Select the appropriate pretreatment process. ;2. Adjust the appropriate curing conditions; 3. Purify the oven; 4. The recovered powder is filtered and mixed with new powder, preferably <30%; 5. Thoroughly clean the powder spraying system before changing the powder; 6. The replacement quality is good of powder.
6. There are pores and pinholes in the coating film
Causes: 1. There are pores on the surface of the workpiece; 2. There is residual liquid on the surface of the workpiece, and the degreasing and rust prevention are not complete; 3. The conductive putty is too thick and not dry; 4. The spray gun is too close to the workpiece, and the construction voltage is too high 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 the powder coating itself
Solutions: 1. Strengthen the processing of the workpiece; 2. Improve the pretreatment 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, adjust curing conditions; 7. Replace qualified powder coating.
7. The mechanical properties of the coating film are poor, and the coating falls off in one piece
Causes: 1. The quality of the base material is poor, and the pretreatment method is improper; 2. The baking conditions are improper, the curing is not complete or the baking is over; 3. The powder quality is poor, or the shelf life has expired.
Solutions: 1. Improve the pre-treatment; 2. Determine the appropriate baking process; 3. Select qualified powder, and a comprehensive inspection is required if it is overdue.
8. The coating film has poor corrosion resistance
Causes: 1. The coating film is not fully cured; 2. The temperature of the baking furnace is uneven and the temperature difference is large; 3. The workpiece is not handled properly; 4. The performance of the powder coating is poor
Solutions: 1. Adjust the baking conditions according to the performance of the coating; 2. Choose a suitable oven, with a temperature difference of ±5°C; 3. Strengthen the pre-treatment to prevent the treatment liquid from remaining on the surface of the workpiece; 4. Replace the qualified powder coating.
9. Powder flying poor adsorption
Causes: 1. No high voltage generated by the electrostatic generator or insufficient high voltage; 2. Poor grounding of the workpiece; 3. Excessive air pressure; 4. Blockage of the air duct in the recovery device; 5. Incomplete pre-treatment (rust, oil); 6. Powder Problems with the paint itself
Solutions: 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 coating.
10. The amount of powder supplied is uneven, and the amount of powder sprayed is sometimes high and sometimes low
Causes: 1. The powder pipe is partially blocked, and the powder fluidity is poor; 2. The air pressure is insufficient and the pressure is unstable; 3. Oil and water are mixed in the air; 4. The fluidization of the powder feeder is unstable, and the powder in the powder feeder is too little .
Solution: 1. Clean up the debris or agglomeration of the powder pipe, keep the powder pipe unblocked, and adjust the flow of powder coating dry powder; 2. Choose a suitable air compressor; 3. Regularly remove the oil and water in the air compressor; 4. Keep the air pressure of the fluidized bed stable, and add new powder regularly.
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