The reasons of excessive particles on the powder coating aluminum profile

A common problem for powder spray technicians is the particles-particles protruding from the surface of the powder coating. Particles seriously affect the decorative nature of aluminum profile surface coatings. So how do powder particles are produced and how can they be reduced?

1.Processing of powder coating aluminum profile

Spraying should try to the surface of the coated work piece polished smooth, flat, the surface does not have oxidizing skin and fine holes, if there are conditions can also be pre-baked, but also effectively reduce the formation of particles.

2.Surface treatment of aluminum profile

General powder spray aluminum work parts need to go through the following process: racking - de-oiling - washing - chroming-......- - curing - discharge, wherein in the surface treatment process of chromium residue and other impurities may attach to the work piece, resulting in the presence of film-forming particles.

3. The surrounding production environment of the powder spray room.

The surrounding production environment of the powder house will directly affect the surface quality of the coating film, for the electrostectant discharge of the electrostectant spray gun coating, some dust and particulate matter in the environment is brought into the powder coating powder room, through electrostitive action to make charged impurities adsorption on the surface of the coating, in the powder melting flow usually, become film surface particles. A clean production environment has a good effect on product quality.

4.The thickness of powder coating

For the spraying of technical personnel, all understand that if the coating film is too thin, in addition to the particles will appear, but also will produce a level difference, orange peel serious, and light color varieties of poor masking force, while the coating of acid resistance, alkali resistance, salt resistance, water resistance and other poor performance. Appropriate increase in film thickness, can effectively reduce the formation of particles, coating film should not be too thick, generally too thick words will affect the size of the coated work, in impact resistance, flexibility, adhesion and other performance decline, the general coating thickness control in 40 to 120um or so for normal.

We can control the film thickness in the following ways.

　　A, the number and arrangement of spray guns in the powder room;

　　B, the amount of powder and air pressure of the spray gun (powdering, atomization, fluidization parameters);

　　C, the speed of the transmission chain, that is, the speed of the chain;

　　D, the suspension and arrangement of the coated work piece.

5. The treatment of recycled powder.

For most enterprises, recycled powder generally has the following treatment: 1, conveyor belt recovery of fully automatic powder coating system, sprayed powder after automatic recovery screening, and then mixed with the new powder coating to continue to supply powder spray gun, the quality of this recovery powder is relatively stable, not easy to produce particles; 2, cyclone separator and bag filter polar recovery system, cyclone separator first-level recovery of powder after vibration screening and powder supply system circulation, the basic impact on the coating is small, also not easy to produce particles; The recycling and reuse of powder, adsorbed on the surface of the profile only accounts for about 1/3 of all spray gun powder, scattered in the spray room more powder, recycling powder must be mixed with new powder in an appropriate proportion, the effect is better, so the powder should be recycled in a timely manner.

6. The powder coating itself has particles.

The particles of powder coating can be divided into mechanical impurities and gel particles. Mechanical impurity particles are mainly derived from the material itself, the production process and equipment wear, the production process brought into the environment of the debris, glycation particles are mainly from the production process of extrusion process used in the resin raw materials. Therefore, we should strengthen the raw materials into the factory inspection, to prevent such a situation.