That is, the distance of spraying, the trajectory of operation, and the overlap of spraying are important factors that directly affect the spraying quality of the spray gun. You must pay attention to it during normal operation.
1. Spraying distance
Spraying distance refers to the distance from the nozzle of the water-based spray gun to the object to be coated. The traditional air spraying distance is 20-30cm for large spray guns and 15-25cm for small spray guns. The spraying distance of the electrostatic spray gun is generally 20 to 30 cm.
If the spraying distance is too short, the coating film formed per unit time will be thick, which is easy to cause sagging; if the spraying distance is too long, the coating film will be thin and the loss of coating will increase. In severe cases, the coating film will have no gloss.
2. The trajectory of the operation
The trajectory of water-based paint spray gun operation needs to consider two aspects: the angle of spraying and the running speed of the spray gun. When spraying, keep the spray gun running at right angles and parallel to the surface of the object to be coated. The moving speed of the spray gun is generally adjusted within the range of 30 to 60 cm/s and is required to be constant.
If the high quality spray gun is inclined and runs in an arc trajectory or the running speed is variable, the uniform thickness of the coating film will not be obtained, which will easily cause the coating film to produce flowers, orange peel and sagging.
3. Atomization and spray range
The overlap width of the spray pattern should be kept constant. If the overlap width is variable, the film thickness is not uniform, and the coating film is prone to defects.
After the water-based paint spray gun is used, spray and clean with the thinner of the sprayed paint until the paint channel of the spray gun is cleaned. Otherwise, the paint in the gun will become dry and clogged, which will affect the normal use of the spray gun.
(1) Specific cleaning method of water-based paint spray gun
1. Turn off the compressed air, remove the paint storage tank, pour the paint in the gun back into the paint storage tank, and pour the paint in the tank into the container;
2. Pour about 1/4 volume of solvent into the paint storage tank for washing, install the paint storage tank, turn on the compressed air, and repeatedly rock and spray several times;
3. Disassemble the spray head, clean it with solvent and install it; wipe the paint on the gun body.
(2) Pay attention to the following points when washing water based paint spray gun:
1. Use soft brushes when scrubbing, metal brushes are forbidden, hard objects are not allowed to poke or scrape, to prevent the nozzle from being worn and the shape of the jet to change;
2. Avoid soaking the spray gun directly in the solvent to prevent the residual paint from attaching to the machine parts and dissolving the lubricating oil on the gun. You can use a soft cloth moistened with solvent to wipe it;
3. The knurled parts on the high-quality spray gun are adjusted by hand, avoiding the use of pliers tools;
4. Regularly drip lubricating oil on the needle valve and bolt pin shaft;
5. Regularly apply light grease or petroleum jelly to lubricate the needle valve and needle valve spring, and do not use silicon-containing oil.