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 coating process involves three main steps:
Part Preperation and Pre-Treatment
Removal of oil, dirt, 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 method to be used depends on the size of the part to be powder coated, how clean the part is, where the part will be located (Indoor/outdoor), and the overall performance of the part. However, we recommend abrasive blasting on all parts prior to powder coating. Parts are then hung, washed, and or blown clean.
The Powder Application
We spray the powder using an electrostatic gun. The gun positively charges the powder, which is then sprayed towards the grounded object and then wraps around the workpiece by the powerful electrostatic charge. Pre-Heating the metal before spraying helps reduce the Faraday Cage Effect, and reduces off gassing of trapped oils.
The object is then heated, and the powder melts into a uniform film, and is then cooled to form a hard coating. This cure process requires a certain temperature for a certain length of time in order to reach full cure, and appropriate characteristics. The curing schedule could vary according to types of powder, (Polyester, epoxy, hybrids, etc) and other factors.