Powder Coating is a type of coating that is applied as a free-flowing, dry powder. The main difference between a conventional liquid paint and a powder coating is that the powder coating does not require a solvent to keep the binder and filler parts in a liquid suspension form. The coating is typically applied electrostatically and is then cured under heat to allow it to flow and form a “skin”. The powder may be a thermoplastic or a thermoset polymer. It is usually used to create a hard finish that is tougher than conventional paint.
Powder coating is mainly used for coating of metals, such as household appliances, aluminum extrusions, drum hardware, and automobile and bicycle parts. Newer technologies allow other materials, such as MDF (medium-density fibreboard), to be powder coated using different methods
How Powder Coating Works
Powder coatings are based on polymer resin systems, combined with curatives, pigments, leveling agents, flow modifiers, and other additives. These ingredients are melt mixed, cooled, and ground into a uniform powder similar to baking flour. A process called electrostatic spray deposition (ESD) is typically used to achieve the application of the powder coating to a metal substrate. This application method uses a spray gun, which applies an electrostatic charge to the powder particles, which are then attracted to the grounded part. After application of the powder coating, the parts enter a curing oven where, with the addition of heat, the coating chemical
Advantages of powder coating instead of other coatings
1.Powder coatings contain no solvents and release little or no amount of Volatile Organic Compounds (VOC) into the atmosphere. Thus, there is no longer a need for finishers to buy costly pollution control equipment.
2.Powder coatings can produce much thicker coatings than conventional liquid coatings without running or sagging.
3.Powder coated items generally have fewer appearance differences between horizontally coated surfaces and vertically coated surfaces than liquid coated items.
4.The wide range of specialty effects are easily accomplished using powder coatings that would be impossible to achieve with other coating processes.
The powder coating process
The powder coating process involves three basic steps:
*Part preparation or the pre-treatment
*The powder application