How much do you reallyknow about metal finishing andpowder coating?

First developed in the mid 1940's powder coating entails applying the coating as a free-flowing, dry powder which is subsequently cured under heat to allow it to flow before cooling down to create a skin. This results in a tough coating that is normally harder than a standard wet paint finish whilst providing a similar finish.

There are some very specific advantages to using power coating too. Firstly, not having a liquid carrier, which means that powder coating can result in thicker coatings than conventional liquid coatings without any running or sagging. In addition, with powder coating, there are hardly any appearance differences between horizontally coated surfaces and vertically coated surfaces.

Powder coating can be applied either by dipping the item into a container of powder, which may or may not be electrically charged, or the powder paint is electrically charged and sprayed onto the part being covered. After being coated with completely dry paint, the component is heated in an oven causing the powder particles to liquefy before cooling again to leave a tough, continuous layer of paint.

There are additionally two main types of powder available to use. These are thermoplastic powder, which will melt once more when heat is applied, and thermosetting powder, that will not melt again when heated. When it comes to thermosetting powder, a chemical cross linking reaction is caused when heat is first applied to the powder coating, meaning that the bonds cannot be broken down again, even if the coating is subjected to heat once more. The type of powder that is most suitable to use naturally depends on the application that the coated component is designed for and what sort of temperatures it may be subjected to during use.

When it comes to producing a successful powder coating, it truly does all rely on the preparation of the material being coated. It's the case that most powder coating problems are connected to an inadequate preparation process. It is also important to understand that preparation needs to be different depending upon the material.

The preparation of aluminium is the following... clean, wash, etch, chromate, rinse and demineralised rinse.

Oils or grease have to be cleaned off through the use of weak alkali or neutral detergent solutions and the surface of the item is etched to eliminate heavy oxides.

After rinsing, the aluminium is dipped in a chromate to create an adaptation coating. Next the aluminium is rinsed in demineralised water which removes chemical salts on the aluminium. This procedure serves two functions which include providing the aluminium a surface which is better for adhesion and helping to protect the aluminium from under the paint corrosion.

If you are preparing a steel component, the actions you need to take prepare the material are as the following: clean, rinse, etch, rinse, grain refine, zinc phosphate, rinse and acidulated rinse.

The grain refiner is used after acid cleaning of steel surfaces and prior to zinc phosphate. This is due to the fact that otherwise the zinc phosphate finish generated will certainly be quite coarse and also have a reduced adhesion ability.

So, as you can see, the process of powder coating is not necessarily a simple one. If done correctly, powder coating is able to produce a paint finish that is superior in terms of quality and durability, which it is now used so widely for a large range of applications.