What is Powder Coating?
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. Powder coating is a superior finish that’s found on hundreds of products you come in contact with each day. It makes products durable, attractive, and scratch-resistant, too.
How Does Powder Coating Process work?
The powder coating process involves three basic steps:
1. Part preparation or the Pre treatment: Removal of oil, soil, lubrication greases, metal oxides, welding scales etc. is essential prior to the powder coating process. It can be done by a variety of chemical and mechanical methods. The selection of the method depends on the size and the material of the part to be powder coated, the type of soil to be removed and the performance requirement of the finished product.
2. The powder application: The most common way of applying the powder coating to metal objects is to spray the powder using an electrostatic gun, or Corona gun. The gun imparts a positive electric charge on the powder, which is then sprayed towards the grounded object by mechanical or compressed air spraying and then accelerated toward the workpiece by the powerful electrostatic charge. There are a wide variety of spay nozzles available for use in electrostatic coating. the type of nozzle used will depend on the shape of the workpeice to be painted and the consistency of the paint. The object is then heated, and the powder melts into a uniform film, and is then cooled to form a hard coating. It is also common to heat the metal first and spray the powder onto the hot substrate. Preheating can help to achieve a more uniform finish but can also create other problems, such as runs caused by excess powder.
3. Curing: When a thermoset powder is exposed to elevated temperature, it begins to melt, flows out, and then chemically reacts to form a higher molecular weight polymer in a network-like structure. This cure process, called crosslinking, requires a certain degree of temperature for a certain length of time in order to reach full cure and establish the full film properties for which the material was designed. Normally the powders cure at 200°C (390°F) in 10 minutes. The curing schedule could vary according to the manufacturer’s specifications.The application of energy to the product to be cured can be accomplished by convection cure ovens or infrared cure ovens.
What are the advantages of Powder Coating?
1.More Durable: Powder coating gives consumers, businesses, and industry one of the most economical, longest-lasting, and most color-durable quality finishes available. Powder coated surfaces are more resistant to chipping, scratching, fading, and wearing than other finishes. Color selection is virtually unlimited with high and low gloss, metallic, and clear finishes available. And colors stay bright and vibrant longer. Texture selections range from smooth surfaces to a wrinkled or matte finish, and rough textures designed for hiding surface imperfections.
2. Protects the Environment: Powder coating is also highly protective of our environment. While liquid finishes contain solvents which have pollutants known as volatile organic compounds (VOCs), powder coating contains no solvents and releases negligible amounts, if any, of VOCs into the atmosphere. Thus, there is no longer a need for finishers to buy costly pollution control equipment. In addition, most powder coating overspray that does not adhere to the part can be retrieved and reused, virtually eliminating the waste commonly found in liquid finishing processes.
Which Different Color Charts Are Available?