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.” The powder may be a thermoplastic or a ceramic. It is usually used to create a hard finish that is tougher than conventional paint.

The powder coating process involves three basic steps:


First Step: Part Preparation

Removal of oil, soil, lubrication greases, metal oxides etc. is essential prior to the 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  coated, the type of soil to be removed and the performance requirement of the finished product.


Second Step: Powder Application Processes

The most common way of applying the powder coating to metal objects is to spray the powder using an electrostatic gun. The gun imparts a positive electric charge on the powder, which is then sprayed towards the grounded object by compressed air spraying and then accelerated toward the workpiece by the powerful electrostatic charge.


Step Three:
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.