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Powder-coating metal offers several advantages, especially when compared to painting, making it the best alternative. Its main advantages include its low-cost nature, there is no risk of chipping, it is more environmentally friendly, and it offers better protection to the surface underneath. However, you can only enjoy these benefits and others if you do it well.
Here is a guide on how to powder coat metal with all the steps involved.
The first and crucial stage of the powder coating metal. It ensures the surface is clean, without any debris, and is best placed for the coating to adhere to. The main steps in preparation are;
Washing the metal alone is insufficient; it will not remove inorganic contaminants. That is where blasting comes into play. The blasting process removes rust, laser scale, welding smut, and other such material.
Blasting uses abrasives that help eliminate corrosion, rust, and other finishes. Removing such contamination ensures better and even powder coat adhesion.
The pre-treatment process covers several processes, all designed to clean the surfaces thoroughly. How many processes you go through depends on the level of contamination, available resources, and your diligence.
Firstly, the surfaces are washed with an alkaline cleaner which rids off any organic liquid and dust contaminants. After this step, the metal gets two thorough rinses to clear any cleaning chemicals and surface debris.
The next step, ideally, is to take the metal through iron phosphate application. It helps prepare the surface for better adhesion and improves the metal’s resistance to corrosion. After this, the metal gets dual rinses.
After this, the metal goes through a reverse-osmosis water rinse, which clears any solutions left on the surface. Then a sealer made from chrome-free zirconium is applied to the surface and dries in place, sealing the surface. Once this is done, it sets the stage for the next process.
This step is optional but highly beneficial, especially to steel and aluminum surfaces. Priming steel and aluminum products allows the finish to last four times longer than unprimed surfaces. Thus, if you intend to use aluminum and steel outdoors, you are better off priming it.
The final stage before the application is to block off areas that do not need powder coating. The masking helps protect threads and machined parts, keeping them clean.
With the preparation process all set, it is time to apply the powder coating. Generally, there are two methods, electrostatic deposition (ESD) and fluidized bed powder coating. However, for metals, the preferred application process is ESD. This method uses an electrostatic spray gun, powder feeder, or powder spray booth. In some instances, one can use spray cans.
The fluidized powder material is distributed evenly on the metal surface, and thanks to its electrical charge, they adhere easily to the electrically grounded metal surface. They will stay on the surface for as long as they retain part of their charge.
There is a different curing stage depending on the method of application. Since it is metal, you are powder coating, you are most likely using ESD, and thus you will use the respective curing method. In this case, the curing process will require you to place the parts in a curing oven. How long the part stays in the oven and at what temperature depends on several factors, including the shape and size of the part, the type of substrate, the thickness of the coating, and other factors.
However, on average, you can have the curing oven operating at 325 to 450 degrees Fahrenheit, giving you curing times ranging from ten to sixty minutes. Smaller parts and those with a thin coating will require lesser time and lower temperatures. Once the part gets to an optimum curing temperature, the powder particles will melt and gel together, creating a continuous film along its surface.
Once you finish curing, allow the metal parts to cool completely before you handle them.
Powder coating metal is an intense activity but not beyond the realms of being a DIY project. The challenge, usually, is having the right equipment. Whether you are at home alone or in a business, quality equipment can make the whole difference in terms of efficiency and quality as well as safety and the general after cleaning.
To that end, Ramseier Koatings proves to be a reliable partner with our versatile range of quality solutions. If you are planning a metal powder coating business, reach out to our products section and see their options. We also have excellent customer service that will guide you on the various options and what suits you.