Powder coating is basically a kind of dry finishing process. And this one of the most popular types of finishing processes. Powder coating was introduced in the 1960s. If we talk about the industrial finishing market powder coating represents a total of 15 percent of the whole market.
The companies target powder coating for its high-quality and durable finishing quality and for better profit they have maximized its production. And they have improved efficiencies and simplified environmental compliance. This has been one of the main reason for its success in the market.
Basically, powder coating works as protective or functional and decorative finishes. You will find powder coating a very wide category of colors and range. This article will mainly focus on everything you actually need to know about powder coating.
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The Types of Powder Coating
You will mainly find only two kinds of powder coating in the market. They are thermosets and thermoplastics.
Thermosets vary manly as a cross-linker into this formulation. Specifically to say this powder during baking reacts with other chemicals and components and works to polymerize the powder, improving the performance properties.
But the thermoplastic type does not undergo any additional process during the baking. Rather it flows to form the final coating.
Why Powder Coating is Better Than Other Coatings
- Powder coatings are more environment-friendly than other coatings. If you look closely you will find that powder coating does not contain any kind of solvents that is why powder coating doesn’t release volatile organic components in the atmosphere. That is it is both environmentally friendly and also saves the extra costs of buying any kind of pollution control companies.
- Powder coatings produce a much thicker coating than the other available coatings in the market and these end up sagging in that process.
- In the sector of appearance, there are a few differences in the powder coating than the other available coatings.
- You can get a wide range of special effects that can easily be achieved in powder coating that is very impossible to figure out in the other conventional coatings.
- The curing process is much faster in powder coating than other available coatings.
The Production of Powder Coating
- First, all kind of powder mixture ingredients, hardener, pigment are mixed with polymer granules in an industrial mixture like turbo mixture
- Then the mixture is heated in an extruder
- The mixture then gets molded and cooled
- Then little chips are made out of the mixture
- The chips are turned into powder by milling and sieving it
How Powder Coating Works
Powder coatings are basically a polymer resin system base that mixed with additives like curatives, pigments, flow modifiers, leveling agents. The ingredients go through a process of melting, mixing, cooling, and grounding into forming a powder similar.
On the looks, it looks like baking powder. The process is used to apply the powder on metal is called electrostatic spray deposition (ESD) and this typically goes into achieving the process of applying the powder coating over a metal surface.
This application method comes with using a spray gun, the gun applies an electrostatic charge to the powder and this makes the particles getting attracted to the grounded part.
After the application of the powder, the coating part comes the curing part where, with the addition of heat of the oven, makes the coating chemically react to produce the long molecular chains that result in high cross-link density.
These molecular chains are very resistant to breakdown and this type of application is the most common method of applying powders. Powder coatings can also be applied to a non-metallic object like plastics and medium density fiberboard.
Powder coating is also sometimes applied during a fluidized bed application. This works in dipping the preheated parts into a hopper of fluidizing powder and results in melting the coating.
And then this flows out on the part. Here cure may be needed in the process but that depends on the temperature and the mass of the coating and also the type of powder that is used.
No matter which application process is followed, powder coatings are very easy and money-saving to use. They are also environmentally friendly, durable and tough.
Removing Powder Coating
After we talked about how to apply powder coating and how they work now we will focus on the removing process. Though most of the organic solvents are not effective in removing powder coating, “Methylene chloride” and “acetone” are very effective and workable in the sector of removing the powder coating.
Powerful acid like 98 % sulfuric acid on its commercial-grade removes powder coating very effectively. Aromatic alcohols like Benzyl alcohol also very effectively remove the coating.
Benzyl alcohol has mainly replaced the place of Methylene chloride and acetone very effectively in recent times. Aggressive blasting is one of the major new ways of removing powder coating.
Burning off is also a way of removing powder coating. Basically for this process, you need to put the structure into a large and high-temperature oven for removing it.
The temperature should be for strong base materials close to 300 – 450 °C and for thinner layered materials use a less air temperature or otherwise, your material will be harmed by excessive heat. The whole process is a process of four to five hours. Within this time the coating gets cleaned.
Powder coating is a type of coating that is a bit different than conventional available coating. The available conventional coatings are mainly liquids and used as liquids but powder coating is applied as dry and free flowing.
Where the regular coatings are delivered via an evaporating solvent, powder coating is typically applied “electrostatically” and the curing happens under heat.
There basically two different types of powder and they are basically thermoplastic and thermosets. The coating is basically used to create a hard finish. The finish is more durable and tough than usual paint.
Powder coating is mainly used for coating metals- like your household appliances, aluminum products, vehicle hard wires like your bicycle or cycle or even car parts.