Pathological causes and prevention methods of powder electrostatic spraying

(1) Partial or large-area beaker with coating film

Cause Analysis: The distance between the powder Spray Gun and the workpiece is too close.

Prevention and control methods: keep a distance of 10-25cm between the powder Spray Gun and the workpiece, too close will cause adverse consequences.

(2) The workpiece does not stick to powder, the amount of powder is too small or the powder is easy to fall off

Cause analysis: the degreasing of the workpiece surface is not effective; the voltage is too low during construction; the workpiece is not connected to the hanger, or the workpiece is insulated and dead.

Prevention and control methods: strengthen inspection, and re-grease if the surface is not clean; increase the voltage to the specified value: adjust the contact point to clamp or hang it, and if there is coating, the insulation should be scraped off the film layer.

(3) The thickness of the coating film is uneven, and there is no coating film on the inner surface of the recess or corner

Reason analysis: the workpiece is complex, the electric field distribution is uneven; the voltage is too low or the spraying time is too short; the workpiece is suspended or rotated poorly.

Prevention and control methods: use a brush dipped in powder slurry to repair the place without coating film; electrostatic powder spraying should not be used for workpieces with too complicated shapes, but other construction methods should be used; increase the voltage and prolong the spraying time; adjust the workpiece speed and the movement of the powder Spray Gun Orientation, pay attention to operation, uniform spraying and no leakage of the gun.

(4) The coating film is brittle or the bottom layer is poorly attached

Reason analysis: The performance of the powder coating itself is not good; the dirty oil and rust spots are not cleaned; the water is not quenched after curing or the water is not quenched; the curing temperature is too low or the time is too short. The coating is not fully domesticated.

Prevention and control methods: choose powder coatings produced by reliable quality manufacturers; strengthen pre-treatment construction; construct according to the process, must enter quenching water treatment; solidify according to the temperature and time required by the process.

(5) Sometimes the coating film is too thick or has orange peel, sometimes the coating film is too thin and the covering ability is poor

Reason analysis: the voltage is unstable, when the voltage is high, the amount of powder absorption is large, and the coating film is thick;

Or the spraying time is too long. The workpiece transmission speed is too slow; sometimes the voltage is too low or the hanger is not in good contact, the powder absorption is too small, and the film layer is thin; the spraying time is too short or the workpiece is transmitted too fast, which will also cause the film layer to be too thin .

Prevention and control methods: stabilize the voltage, do not let it fluctuate too much, try to make the voltage output as uniform as possible; master the spraying time, and the workpiece transmission speed should be uniform.