How Does used coating line Work?

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Workpiece Not Attracting Powder 1. The electrostatic spray gun has no voltage or low voltage. 1. Check the wiring and voltage of the spray gun. 2. Poor contact of the workpiece or thick insulation layer on the hanger. 2. Check the contact and grounding of the workpiece, remove the insulation layer of the hanger. 3. Excessive exhaust air volume in the spray booth. 3. Reduce the exhaust air volume. 4. Unreasonable hanger design causing shielding effect. 4. Adjust the hanger. 5. The distance between the workpiece and the spray gun is too far. 5. Adjust the distance between the spray gun and the workpiece. Insufficient Powder Coating on Workpiece 1. Insufficient powder output from the spray gun. 1. Adjust the powder output from the spray gun. 2. Blockage in the powder supply system or pipeline. 2. Unblock the powder supply system or replace the powder supply pipe. 3. Insufficient electrostatic high voltage or poor charging of the friction spray gun. 3. Increase the electrostatic high voltage or check the charging effect of the friction spray gun and powder. 4. Thick cured powder layer on the hanger, causing high resistance. 4. Remove the cured coating on the hanger to reduce resistance. 5. Insufficient powder spraying time. 5. Adjust and extend the powder spraying time. 6. Unreasonable arrangement of the workpiece and spray gun. 6. Adjust the arrangement of the workpiece and spray gun. Excessive Powder Coating on Workpiece 1. Excessive powder output from the spray gun. 1. Adjust the powder output from the spray gun. 2. Electrostatic voltage too high. 2. Adjust the electrostatic voltage. 3. Conveyor speed too slow. 3. Adjust the conveyor speed. 4. Spray gun too close to the workpiece. 4. Adjust the distance between the spray gun and the workpiece. 5. Too many spray guns. 5. Adjust the number of spray guns. Powder Coating Clumping 1. Poor storage stability of powder, or pressure during transportation or storage, and unreasonable powder formula design. 1. When designing the powder formula, select resins and powders with a glass transition temperature that meets the storage stability requirements. 2. Improper storage of powders, with storage temperature higher than the required temperature. 2. Ensure the storage temperature for powders meets the temperature requirements for the specific type of powder. 3. Powder absorbs moisture or is packaged when the temperature is too high. 3. Maintain the required temperature and humidity during powder production. When the powder temperature is high, it must be cooled to a non-caking temperature (varies by type) before packaging. For already caked powder, use mechanical methods to crush and sieve them before use. 4. Excessive content of ultrafine powder coating. 4. Reduce the content of ultrafine powder during the production of powders. Uneven Powder Spray from Gun 1. Uneven powder supply from the powder system. 1. Check the powder supply device for stable powder supply pressure. 2. Accumulation of powder in the powder supply pipeline or spray gun nozzle, causing blockage. 2. Clean the powder supply pipeline and spray gun nozzle regularly to prevent powder adhesion and accumulation. 3. Powder absorbs moisture or cakes. 3. Prevent powder from absorbing moisture, shorten the contact time of recycled powder with air, and limit the proportion of recycled powder added to new powder. 4. Unstable compressed air pressure. 4. Check the stability of the air compressor pressure and the condition of the oil-water separator, ensuring that the compressed air is dry and oil-free. Poor Coating Adhesion Efficiency 1. Voltage of the high-voltage electrostatic generator is too low, resulting in poor electrostatic effect. 1. Increase the voltage of the high-voltage electrostatic generator, and check the grounding of the workpiece and the resistance of the hanger. 2. Poor charging performance of the powder when using a friction spray gun. 2. Check if the amount and type of charging additives in the powder are appropriate. 3. Excessive use of recycled powder. 3. Reduce the amount of recycled powder used. 4. Too much ultrafine powder or excessive exhaust air volume in the spray booth. 4. Decrease the content of ultrafine powder and reduce the exhaust air volume in the spray booth. 5. Powder particles are too coarse or density is too high. 5. Adjust the filler content in the powder formula and the particle size distribution during production. Honeycomb Pattern on Powder Layer 1. Excessive thickness of the electrostatic powder coating layer, causing ion repulsion. 1. Reduce the thickness of the electrostatic powder coating layer or use an electrostatic friction spray gun. 2. Spray gun too close to the workpiece. 2. Increase the distance between the spray gun and the workpiece, generally keeping them more than 150mm apart. Incorrect Powder Color, Yellowing 1. Poor heat resistance of the powder. 1. Use powders with better heat resistance or adjust the formulation to use heat-resistant pigments and additives. 2. Excessive curing temperature. 2. Lower the curing temperature. 3. Conveyor speed too slow, resulting in prolonged curing time. 3. Increase the conveyor speed. Poor Impact Strength of Powder 1. Curing temperature does not meet the process requirements. 1. Check if the curing oven temperature meets the process requirements. 2. Curing time does not meet the coating process requirements. 2. Check if the dwell time of the coated workpiece in the curing oven is sufficient, especially when the thickness of the workpiece changes or the number of workpieces increases, the baking time should be extended. 3. Powder quality does not meet the requirements, or the storage period of the powder has expired. 3. When designing the powder formula, fully consider the requirements for coating impact strength; check if the powder has exceeded its storage period. 4. Poor surface treatment of the workpiece. 4. Check the pre-treatment process and ensure proper pre-treatment. Coating with Pinholes, Bumps, or Particles 1. Poor pre-treatment of the workpiece, with stains or particles. 1. Ensure the quality of the pre-treatment process, making the surface of the workpiece free of stains and impurities. 2. Poor purification of compressed air, containing water or oil. 2. Purify the compressed air of the air compressor. 3. Coating is too thick, causing ion repulsion. 3. Control the coating thickness to be below 150 microns during cold spraying. 4. Powder with blocked curing agents or those that release small molecules during curing is applied too thickly. 4. For powder with blocked curing agents and those releasing small molecules, control the coating thickness to be below 100 microns. 5. Pinholes on the surface of cast iron, cast aluminum, hot-rolled steel plate, and galvanized sheet. 5. For workpieces with sand holes or pinholes, hot spraying is better; if cold spraying is required, add suitable defoamers in the formula. 6. Interference between powders of different types or manufacturers. 6. Clean the powder spraying system thoroughly to prevent interference between different types of powder. 7. Unclean spraying environment with dust and contaminants. 7. Keep the environment around the powder spraying booth clean to prevent contamination. 8. Unclean curing environment for the coating. 8. Maintain a clean curing environment. 9. Impurities falling from hangers contaminating the workpiece. 9. Regularly clean impurities and contaminants from hangers to prevent them from falling. 10. Coating thickness is too thin, resulting in poor leveling. 10. Ensure the coating thickness meets the requirements to avoid being too thin. 11. Raw materials contain non-melting or non-dispersing substances, introducing impurities during powder production. 11. Control the quality of raw materials and maintain a clean environment during production to prevent impurities from entering the product. 12. Extruder not cleaned properly or extrusion temperature too high, causing partial gelling of powder coating particles. 12. Clean the extruder thoroughly and avoid excessively high extrusion temperatures. Coating Sagging 1. Low melt viscosity of the powder coating. 1. Choose resins with high melt viscosity. 2. Excessive coating thickness. 2. Avoid excessive coating thickness. 3. Long gelation time of the powder coating. 3. Adjust the gelation time of the powder coating, adding accelerators to shorten it if necessary. Loss of Gloss, Discoloration 1. Incomplete cleaning of the powder supply and spraying system, leading to contamination with different types or colors of powder. 1. Thoroughly clean the entire system and spray booth when changing powder types and colors. 2. Excessive curing temperature. 2. Control the curing temperature within the process requirements. 3. Curing time too long. 3. Adjust the curing time according to process requirements. 4. Quality issues with the powder material. 4. Use higher quality powder materials. Poor Coating Adhesion 1. Poor pre-treatment of the workpiece, such as inadequate oil removal, rust removal, or phosphating. 1. Strictly perform pre-treatment on the workpiece. 2. Curing temperature of the workpiece does not meet the process requirements. 2. Bake and cure strictly according to the process temperature requirements. 3. Curing time of the workpiece does not meet the process requirements. 3. Bake and cure strictly according to the process time requirements. 4. Powder quality does not meet the requirements or has exceeded its storage period. 4. Adjust the powder formula to improve coating adhesion; do not use coatings that have exceeded their storage period unless they are re-tested and found to be qualified or modified to meet standards. 5. Thermoplastic powder coating was applied without a primer. 5. Apply a primer when high adhesion is required for thermoplastic powder coatings. 6. Coating thickness is too thick. 6. Adjust to the appropriate coating thickness. Poor Resistance to Acid, Alkali, Salt, and Water 1. Poor pre-treatment of the workpiece. 1. Strictly control the quality of pre-treatment. 2. Pinholes or uneven thickness in the coating. 2. Improve powder coating quality to ensure necessary coating thickness and uniformity. 3. Curing temperature did not meet process requirements. 3. Adhere to the specified baking temperature for curing. 4. Curing time did not meet process requirements. 4. Follow the process requirements for curing time.