Powder coating process is the process in which dry powder is first electrostatically charged and then applied as a coating on the product surface. It offers one-coat finish in varying thickness ranging from 20micron to 1000micron. Powder coating possesses properties such as anti-weathering, anti-corrosion, chemical stain resistance, and formability.
Continuous advancement in powder coating engineering has broadened its applications. New, useful powders are continuously being developed to suit customer needs. Factors such as adherence of powder coating to environmental concerns due to low volatile compound emission, cost efficiency, and finish quality are the driving factors.
Powder coating process has to meet stringent regulatory norms. Installation & maintenance cost of powder coating plant is high. Due to low awareness of its advantages, customers are reluctant to switch from conventional paint technology. Increasing prices of raw materials, increased usage of plastic is restraining the market.
Powder coating uses raw materials such as epoxy resin, maleate & acrylate polyester, bifunctional polyester resin, acrylic resins, silicone, COOH polyester resin, OH polyester resin aromatic polyesters, thermoplastic resins, curing agents and functional additives. The process consists of powder coating spray guns, ovens, and conveyors. Powder application uses electrostatic fluidized bed coating, electrostatic, magnetic brush coating, and curing process.
A powder coating line differs from a batch powder coating set up in that the parts to be coated are placed on a moving conveyor, whereas a batch system is either a manual rolling cart or individual parts that can be moved by hand on hooks. For a line, the conveyor is usually on a chain-type drive system. Hooks are place along the conveyor, and the parts to be coated are hung on the hooks.
Then the parts go through several areas along the line to pre-treat/clean them and eventually coat/cure them. This varies depending on the powder coating line, but a typical one would include a wash/rinse or pre-treatment of some kind to remove oils or other contaminants, and perhaps a dry-off oven to prepare the parts for coating. Then the parts would go through either a manual or automatic powder coating booth where the parts would get coated. Finally the parts go through an oven where they would be heated for the correct temperature and length of time to cure the powder. After the oven, they would be removed from the line.
As indicated before there can be variations to this, but that is the general process for many powder coating lines.