Common problems and solutions of electrostatic coating spraying process

Update:12-06-2020
Summary:

Common electrostatic coating spraying process problems […]

Common electrostatic coating spraying process problems mainly come from particles in the dusting environment and impurities caused by various other factors, which are roughly as follows:

 

Coating impurities

(1) Impurities in the curing furnace. The solution is to use a damp cloth and a vacuum cleaner to thoroughly clean the inner wall of the curing oven, focusing on the gap between the hanging chain and the air duct. If it is black large particles of impurities, you need to check whether the filter of the air supply pipe is damaged, and replace it in time.

(2) Impurities in the powder spraying room. Mainly dust, clothing fibers, equipment abrasive particles and dust accumulation system dust. The solution is to use compressed air to purge the powder-spraying system every day before starting work, and thoroughly clean the powder-spraying equipment and powder-spraying room with a damp cloth and vacuum cleaner.

(3) Hanging chain impurities. It is mainly the product of suspension chain oil baffle plate and primary spreader water tray (made of hot-dip galvanized plate) corroded by pre-treatment acid and alkali vapor. The solution is to clean these facilities regularly

(4) Powder impurities. The main reasons are excessive powder additives, uneven pigment dispersion, and powder spots caused by powder extrusion. The solution is to improve the powder quality and improve the powder storage and transportation method.

(5) Pre-treatment impurities. It is mainly caused by large particles of impurities caused by phosphating slag and small impurities caused by yellow rust of phosphating film. The solution is to clean up the slag accumulated in the phosphating tank and spray pipe in time, and control the concentration and proportion of the phosphating tank liquid.

(6) Water quality impurities. Mainly due to impurities caused by excessive sand content and salt content in the water used for pretreatment. The solution is to add a water filter and use pure water as the last two levels of cleaning water.

Coating shrinkage

(1) The shrinkage pores caused by the residual of surfactant caused by the pre-treatment degreasing or the washing with water after degreasing. The solution is to control the concentration and proportion of the pre-degreasing tank and the degreasing tank liquid, reduce the amount of oil in the workpiece and strengthen the washing effect.

(2) Shrinkage caused by excessive oil content in water quality. The solution is to increase the water inlet filter to prevent oil leakage from the water supply pump.

(3) Shrinkage caused by excessive moisture content of compressed air. The solution is to discharge the compressed air condensate in time.

(4) Shrinkage caused by wet powder. The solution is to improve the powder storage and transportation conditions and add a dehumidifier to ensure that the recovered powder is used in time

(5) Shrinkage holes caused by oil stains on the suspension chain being blown onto the workpiece by the air conditioning wind. The solution is to change the position and direction of the air supply outlet.

(6) Shrinkage caused by powder mixing. The solution is to thoroughly clean the powder spray system when changing powder

Coating color difference

(1) Color difference caused by uneven distribution of powder pigment. The solution is to improve the quality of the powder and ensure that the L, a, and b of the powder are not much different and the positive and negative are uniform.

(2) Color difference caused by different curing temperatures. The solution is to control the set temperature and conveyor chain speed to maintain the consistency and stability of the curing temperature and time of the workpiece.

(3) Color difference caused by uneven coating thickness. The solution is to adjust the spraying process parameters and ensure that the spraying equipment operates well to ensure the coating thickness is uniform.

In short, there are many powder electrostatic spraying technologies and their application methods, which need to be used flexibly in practice.

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