Powder coating is a dry finishing process used to apply a dry coating material. The coating material is made up of finely ground particles of resin and pigment for color, along with other additives for specific functions such as gloss or hardness. The dry powder coating is delivered to a spray gun tip that is fitted with an electrode to provide an electrostatic charge to the powder as it passes through a charged area at the gun tip. The charged powder particles are attracted to a grounded part and are held there by electrostatic attraction until melted and fused into a uniform coating in a curing oven.
Since its introduction more than 40 years ago, powder coating has grown in popularity and is now used by many manufacturers of common household and industrial products. In North America, it is estimated that more than 5,000 finishers apply powder to produce high-quality, durable finishes on a wide variety of products. Powder-coated finishes resist scratches, corrosion, abrasion, chemicals and detergents, and the process can cut costs, improve efficiency and facilitate compliance with environmental regulations.
Because powder coating materials contain no solvents, the process emits negligible, if any, volatile organic compounds (VOCs) into the atmosphere. It requires no venting, filtering or solvent recovery systems in the application area such as those needed for liquid finishing operations. Exhaust air from the powder booth can be safely returned to the coating room, and less oven air is exhausted to the outside, making powder coating a safe, clean finishing alternative and saving considerable energy and cost.
Theoretically, 100 percent of the powder overspray can be recovered and reused. Even with some loss in the collection filtering systems and on part hangers, powder utilization can be very high. Oversprayed powder can be reclaimed by a recovery unit and returned to a feed hopper for recirculation through the system. The waste that results can typically be disposed of easily and economically.
Powder coating requires no air-drying or flash-off time. Parts can be racked closer together than with some liquid coating systems, and more parts can be coated automatically. It is very difficult to make powder coating run, drip or sag, resulting in significantly lower reject rates for appearance issues.
Powder coating operations require minimal operator training and supervision when compared with some other coating technologies. Employees typically prefer to work with dry powder rather than liquid paints, and housekeeping problems and clothing contamination are kept to a minimum. Also, compliance with federal and state regulations is easier, saving both time and money. In short, powder coating can provide the five “Es:” economy, efficiency, energy savings, environmental compliance and an excellent finish.
Read more: The Powder Coating Process