Coating methods and precautions of metal powder coatingby Lee Dora none
Metal powder coatings are those various powder coatings that containing metallic pigments (such as: copper powder, nickel powder, silver, aluminum, etc.). Since the metal powder coatings can demonstrate a bright, luxurious decorative effect, it is very suitable for furniture, jewelry, cars and other indoor and outside objects spraying.
In the manufacturing process, the current Chinese market is mainly taking the Dry-Blending method, the international community also use Bonding method. In most cases, we recommend using an electrostatic gun for coating. Metal powder coating’s coating method, the friction gun is generally not suitable for the coating of metal powder coating. Due to this type of products containing metallic pigment, while using an electrostatic gun in construction should ensure that the system is well grounded, setting a lower electrostatic voltage and powder amount at the same time, prevent generating ignition when spraying. The effect of forming a coating film and the gun setting, the quality or brand has a great relationship. After longtime spraying, there are may be a lot of metal powder accumulated in the gun discharge needle, which required the constructor regularly clean up the discharge needle.
The shine of metal powder coatings in most cases due to the error is large, we do not recommend using gloss device to measure metallic appearance coating gloss, but only by visual comparison method to determine whether it is the same with sample. The recyclability of the metal powder coating for the powder manufactured by dry mixing method, because of in the process of spraying and recovery will occur separation, thus there are some differences on recycling powder and new powder’s metal pigment content, may cause the coating film appearance inconsistencies, appear color cast. This is because the metallic pigment and the nature of powder particles difference. Experts recommend that the reclaimed powder and new powder’s ratio should at least 1:4.
If use adhesive fixing method manufacturing powder coating, due to the ratio of metal pigment and powder particles is relatively fixed, then it could re-use recycled powder. Spray varnish layer on metal powder layer has the following advantages: Enhanced metal powder coating’s anti-stoning properties; increase the aesthetic effect of the coating metal powder; completely solve the scraped property of metallic pigment; improve weatherability of the coating metal powder. To ensure the appearance of varnish layer, requiring workpiece by first spraying should not be subject to any contamination. Thus, it generally needs for fully automated spray lines and two separate rooms for each spray painting.
Recommended under normal circumstances do not spray varnish layer. Only using in very demanding, such as: high-end appliances, car wheels and outdoor use (to ensure durability) and so on. Metallic pigments’ scraped property, either by dry-blending method or bonding method manufacturing powder, were not completely solve the problem of metallic pigments’ scraped property. The only way to solve the scraped property is spraying a layer of transparent coating film in the metal powder layer. The method to keep the metal powder coating appearance consistent: for the same product, try to use the same batch of metal powder coatings, avoid the difference between powder coatings batches; keep spraying conditions stabilize.
Using the same set of spray equipment, using the same voltage, pressure and other parameters, try to keep the gun and the workpiece distance not change, try to keep the stability of the film thickness; guarantee powder coatings have been fully fluidized before spraying; while using recycled powder should ensure the ratio of recovery powder and new powder less than 1:4; recommend multiple parts to be assembled together spraying at the same time.
Created on Dec 31st 1969 18:00. Viewed 0 times.