Spraying should be as far as possible on the surface of the coated workpiece polished smooth, smooth, the surface without oxide and micro-pores, if conditions can also be pre-baked, but also effectively reduce the formation of particles.

For the technical personnel ofthermal powder spraying, all understand that if the coating film is too thin, in addition to the appearance of particles, will also produce flow adjustment, orange peel serious, and light color varieties of poor hiding power, at the same time coating film acid, alkali, salt, water resistance and other poor performance. Appropriate increase in coating thickness, can effectively reduce the formation of particles, coating film should not be too thick, generally too thick will affect the size of the coated workpiece, in impact resistance, flexibility, adhesion and other properties decline, general coating thickness control in 40~120um is normal. We can control the film thickness by the following ways: a. the number and arrangement of spray guns in the powder chamber; B. Powder output and air pressure of the spray gun (powder output, atomization and fluidization parameters); C. The running speed of the transmission chain, that is, the chain speed; D. Suspension and arrangement of coated workpieces.

For most enterprises, the recycled powder is generally treated as follows

1. In the automatic powder coating system recovered by the conveyor belt, the escaped powder is automatically recovered and sifted, and then mixed with the new powder coating to continue to be supplied to the powder spraying gun. The quality of such recovered powder is relatively stable and it is not easy to produce particles;

2. In the two-pole recovery system of cyclone separator and bag filter, the powder recovered in the first stage of cyclone separator has little influence on coating and is not easy to produce particles when it is sifted by vibrating screen and circulated with the powder supply system;

3. for the manual spraying coating system to recover the powder, because the dust and impurities in the environment is easy to bring into the recovery of powder, recovery must go through more than 120 mesh vibration screen. For the recycling and reuse of powder, the powder adsorbed on the profile surface only accounts for about 1/3 of the powder output of all the spray guns. There are many powders scattered after thermal powder spraying. The recycled powder must be mixed with the newly added powder in an appropriate proportion to achieve good results.

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