When it comes to surface finishing, powder coating is one of the methods commonly used. This is mainly because it combines both protection and aesthetics seamlessly. In addition, it provides extra durability to aluminum surfaces and it is possible to achieve a variety of colors. The method keeps gaining popularity particularly when it comes to powder coating aluminum.
What is Aluminum Powder Coating?
Aluminum powder coating is a technique used to coat aluminum metal parts or objects by fusing dry powder with the help of an electric charge. It is then cured to achieve a seamless, smooth coating. The resulting hard finish is tougher as compared to conventional paint.
Since aluminum is naturally a lightweight metal, it has many functional and aesthetic applications. Even though it has excellent corrosion resistance, some applications require extra corrosion protection. This is achieved by aluminum powder coating. Also, the process improves wear resistance, surface finish, and color.
Powder Coating Process for Aluminum
Aluminum powder coating is a multi-stage surface finishing method. The process involves preparation, application, and curing stages. This process requires a spray booth, spray gun, and curing oven. The dry powder is applied to the aluminum’s pretreated surface, melted, and then hardened into a protective coating.
Preparation Stage
The first step is to clean and treat the aluminum finish to ensure it is free of debris, dirt, and dust. If cleaning is not done properly, any remaining deposits and residues could have an impact on the quality of the finish.
The common steps involved in this stage include rinsing, cleaning, blasting, etching, and drying. Used equipment includes blast rooms, wash stations, and drying ovens.
Neutral detergents and weak alkalis are used to remove oil, solvents,
grease, and other residues. The wash station sprays the parts and surfaces with steam, detergents, and other solutions to clean the parts before coating.
If the surface requires some areas to remain uncoated, then masking products are applied before the application stage. These products are mainly made of plastic film or paper coated with pressure-sensitive adhesives. This ensures they adhere to the substrate and protect it from getting into contact with the powder.
Application Stage
There are two major methods employed by finishing service providers. These are fluidized bed powder coating and electrostatic deposition (ESD).
- Electrostatic deposition. In this case, the dry powder is applied through electrostatic spray deposition. The method utilizes a spray booth, spray gun, powder feeder, and power unit. The work area is the spray booth, which also serves as an air filter. In addition, it also contains powder overspray. Recovery systems collect overspray material.
- Fluidized bed powder coating. In this method, preheated parts and surfaces are dipped into powder material. It is also possible to use electrostatic fluidized bed powder coating.
Curing Stage
The characteristics and particularities of the curing stage are determined by the application method.
- Curing electrostatic deposition coated parts. These parts are cured in an oven and the cure schedule is dependent on part size, thickness, and shape. Usually, the oven operates between 300 to 500 degrees Fahrenheit. The process takes between 10 to 60 minutes. When the part attains the optimal curing temperature, powder particles melt and form a smooth finish across the surface of the part.
- Curing fluidized bed coated parts. Preheated parts are immersed in the coating material. As a result, powder particles melt when they come into contact with the part’s heated surface.
When the powder coated part has cooled, it can be assembled, packaged, or shipped.
Benefits of Powder Coating Aluminum
Aluminum powder coating process provides a range of benefits over traditional liquid coating techniques. Some of its advantages include capabilities for specialized finishes, quick turnaround time, low material costs, less environmental impact, and improved durability.
Enhanced Aesthetics
By powder coating aluminum, it is possible to enhance the appearance of surfaces. It does not matter whether you want to achieve a glossy, textured, or matte finish, it is possible with powder coating. Also, you can produce parts with a wide range of colors.
Durability and Protection
Scientific studies have shown that powder coatings are more durable than liquid paints. This is because they provide higher resistance to moisture, chemicals, wear, and impact. In addition, they provide better protection from abrasion, fading, corrosion, and scratches. This explains why powder coated aluminum is suited for high-traffic and high-use applications.
Environmental Friendliness
With powder coating, there are no carbon dioxide and solvent emissions, surface primer requirements, and hazardous waste material. As a result, the process limits the amount of carcinogenic and toxic substances that get into the environment. This explains why the powder coating industry is considered to be more environmentally friendly compared to liquid coating.
Since the process allows for the collection of overspray material, it can be recycled for future use. This reduces the amount of waste that requires disposal.
Cost-Effective
Powder coating aluminum has lower costs in the long term than the liquid coating technique. This is attributed to its higher coating material utilization and quick turnaround. After the curing stage, parts can be assembled and shipped immediately. Therefore, manufacturers can have a quick turnaround and minimal storage requirements.
Limitations of Powder Coating Aluminum
Although this process has many benefits over conventional liquid coating, it has its share of limitations. For instance, it can produce thick coats that lack uniformity, it is challenging to coat complex parts and minor touchups. Also, it fades over time when exposed to direct sunlight.
Is Powder Coating the Best Aluminum Finish?
Powder coating aluminum parts are a great choice for making them more aesthetically appealing and durable. On surface protection, it is less likely to flake or chip. Also, it requires minimal maintenance. However, how does it stack up against other aluminum surface finishing methods, like liquid painting or anodizing?
Liquid painting is more expensive than powder coating. If a part requires improved appearance or better aesthetics, then liquid painting is the right choice. However, if a part only needs functional requirements, then powder coating is desirable. This is because it has good properties, such as anti-corrosion, wearproof, and waterproof. According to experts at Sunrise Metal, powder coating is more durable and provides high-end protection.
Powder coating is cheaper to apply and provides more color options as compared to anodizing. However, anodized aluminum is more wear and corrosion-resistant than powder-coated aluminum. Also, powder coating cannot achieve uniform film on complex parts.