Pneumatic spray gun use and maintenance tips

Pneumatic spraying spray gun is a coating method that uses compressed air or other means as power to spray the paint from the nozzle of the spray gun and form a uniform coating film.

The use and maintenance of pneumatic spraying gun:

a. choose the appropriate spray gun and determine the size of the nozzle, spraying distance and appropriate air pressure. General coating and nozzle relationship: putty, nozzle diameter 3.5~4.5mm; Bottom viscosity coating, nozzle diameter 1 ~ 1.5mm; High viscosity coating, nozzle diameter 2 ~ 3mm. The relationship between spraying object and nozzle: small spraying object, nozzle diameter 1 ~ 1.5mm; Large spraying area, nozzle diameter 2.5 ~ 3mm; Spray all kinds of text, pattern, nozzle diameter 0.2 ~ 1.2mm. The distance between the spray gun and the coated material has great influence on the quality of the film. The distance is too close, the paint layer is thick, resulting in flow hanging, orange peel and other phenomena; The distance is too far, the paint film is too thin, the paint loss is large, the paint film is easy to fall off, the paint film is not smooth, and the luster is greatly reduced when it is serious. The general distance is 200 ~ 300mm, the small diameter spray gun is 150 ~ 250mm, and the spray distance of the large diameter spray gun is controlled in 200 ~ 300mm. The spraying pressure can be adjusted according to the size of the nozzle and the properties of the paint. Generally, the coating with high viscosity uses a higher pressure, such as the pressure of sub-spraying is generally 0.35mpa. The pressure of high viscosity coatings is 0.25~ 0.30mpa, and that of low viscosity coatings is 0.1~ 0.15mpa. The air pressure is too high, the atomization is fine, but the paint spatter more, the loss is large. On the contrary, if the pressure is insufficient, the spray will be thick, resulting in orange peel, pinhole and other defects.

b. The coating should be properly prepared before spraying, and the viscosity of the coating should be adjusted with thinner. The viscosity is too large, the atomization is not good, the paint film is rough and dark; If it is too thin, it will produce a stream. The suitable viscosity is 16~35S(coated -- 4 cups). When loading the paint storage tank, it should not be too full, with 2/3 as appropriate, tighten the elastic knob.

c. When the pneumatic spraying gun is used, the trigger is held by hand, and the passage of compressed air is first opened, and then the passage of paint nozzle is opened. The compressed air is passed by the pipe through the nozzle, at which time the paint flows out of the nozzle and blows the paint onto the workpiece. When the trigger is released, the orifice of the paint nozzle is tightly closed by the thimble, and the flow of compressed air is blocked.

d. After spraying, the excess recyclable paint should be poured back into the original paint bucket, and then the spray gun should be cleaned. No paint residue is allowed in the spray gun. When cleaning the spray gun, the paint can be poured into the corresponding thinner, pull the trigger, the solvent is ejected from the nozzle, so that the paint tube can be cleaned. Then turn off the compressed air, remove the spray gun and wipe it clean with solvent. Use a fluxing brush to carefully clear the air cap, nozzle and gun body. When the air hole is blocked, use a cork needle to unclog it. Check the airtightness of the needle valve gasket and air valve gasket, grease the sealed ring, and suspend.