Common problems and solutions for metal spraying

Metal Powder Coating The working principle is almost the same as that of ordinary electrostatic spraying of liquid coatings, except that powder coating is dispersed instead of atomized. It is a coating sprayed with an electrostatic powder spray gun, which makes the powder particles negatively charged while being dispersed. Under the action of airflow and electrostatic attraction, the charged powder particles are coated on the grounded coating, and then heated and melted to solidify into a film. The following introduces common problems and solutions in metal powder coating operations.

Common impurities mainly come from particles in the powder coating environment and other impurities caused by various other factors, summarized as follows: (1) Impurities in the curing oven. The solution is to clean the inner wall of the curing oven with a wet cloth and vacuum cleaner, and the gap between the hanging chain and the air duct. (2) Impurities in the powder spraying room. It is mainly dust, clothing fibers, equipment abrasives and powder spraying system dirt. The solution is to use compressed air to purge the powder spraying system before starting work every day, and clean the powder spraying equipment and powder spraying room with a wet cloth and vacuum cleaner. (3) Hanging chain impurities, which are products of the corrosion of the hanging chain baffle and the spreader baffle by the acid and alkali vapors of the pretreatment. The solution is to clean these facilities regularly! (4) Powder impurities, mainly caused by excessive powder additives, uneven pigment dispersion, and powder extrusion producing powder spots. The solution is to improve the powder quality and improve the powder storage and transportation methods.

Metal Powder Coating Coating shrinkage: (1) Shrinkage caused by residual surface active agents due to incomplete oil removal or rinsing with dirty water after oil removal in pretreatment. The solution is to control the concentration and ratio of the pre-degreasing tank solution and degreasing tank solution, reduce the oil content of the workpiece, and enhance the cleaning effect. (2) Shrinkage caused by excessive oil content in the water quality. The solution is to add an intake water filter to prevent oil leakage from the water supply pump. (3) Shrinkage caused by excessive water content in the compressed air. The solution is to discharge the compressed air condensate in time. (4) Shrinkage caused by powder moisture. The solution is to improve the storage and transportation conditions of the powder, add a dehumidifier, and ensure the timely use of the recovered powder. (5) Oil stains on the hanging chain are blown onto the workpiece by the air conditioner, causing shrinkage. The solution is to change the position and direction of the air conditioner air outlet. (6) Shrinkage caused by mixed powder. The solution is to clean the powder spraying system when changing powder.

Metal Powder Coating Coating color difference: (1) Color difference caused by uneven distribution of powder pigments. The solution is to improve the quality of the powder. (2) Color difference caused by different curing temperatures. The solution is to control the set temperature and the speed of the conveyor chain to maintain the consistency and stability of the workpiece curing temperature and time. (3) Color difference caused by uneven coating thickness. The solution is to adjust the process parameters of powder spraying and ensure the good operation of the powder spraying equipment to ensure the uniform coating thickness.

Metal powder coating technology emerged in the 1960s and is mainly used for metal surface coating. In the late 1990s, with the development of powder coatings and spraying equipment, it became possible to apply metal powder coating technology to non-metal surfaces.