Aluminum Powder Coating: Tout ce qu'il faut savoir

Aluminum powder coating is a simple way to protect and color your aluminum parts. This method helps your parts last longer and look better. It protects against rust, scratches, and sunlight.

In this guide, you’ll learn how aluminum powder coating works, how thick it should be, what powders you can use, and what to keep in mind during the process.

Qu'est-ce que le revêtement par poudre ?

Powder coating is a dry way to coat a surface. You spray tiny particles of color and resin onto the part using an electric charge to make them stick.

Unlike liquid paint, you don’t need any solvents. After spraying, you heat the part so the powder melts and forms a strong, smooth finish that lasts a long time.

Aluminum Powder Coating Process

If you’re planning to powder coat your aluminum parts, it’s helpful to understand what actually happens. Here are the steps of the process so you know exactly what your parts go through.

Aluminum Pretreatment Coating Process

Before anything else, your aluminum parts need to be cleaned really well. This step gets rid of surface dirt, oil, mill scale, and other grime. The cleaning is done in a few stages: washing, alkaline cleaning, solvent cleaning, and rinsing. This makes sure the part is totally clean before the next step.

Préparation de la surface

Once the part is clean and smooth, the surface needs to be made a little rough. This helps the powder stick better. There are two ways to do this: one is called sweep blasting, and the other is phosphate treatment.

Both work well, and the shop doing the coating will choose which one to use. In both methods, a rough texture is added to the surface so the powder can hold on during the next step.

Powder Application

Now it’s time to apply the powder. A special spray gun is used to shoot the powder at your aluminum part. The powder has an electric charge, and your part is grounded. This causes the powder to stick tightly to the surface. If needed, this can be repeated to get a thicker coating.

To get the right thickness (between 60 and 80 microns), you should spray the powder in layers using different directions. In the first pass, spray 20 microns of powder going up and down. In the second pass, spray another 20 microns, but this time go left and right.

For the third pass, go up and down again with another 20 microns. Then, in the fourth and final pass, spray left and right once more with 20 microns. This back-and-forth motion helps you get even coverage and a smooth, consistent finish.

Curing

In this step, your coated part is placed in an oven at about 400°F for 10 to 20 minutes. The heat melts the powder and turns it into a solid, smooth, and tough finish. If the coating is thick, it might need more time and a higher temperature to cure properly.

Refroidissement

Once your part finishes baking in the oven, you need to let it cool down. This cooling step helps the coating set properly and form a strong finish.

Inspection

After the parts have cooled, you should inspect them to make sure the paint is spread evenly.

You’ll need to run a few tests, like a scratch test, a punch test, and a micron test. These tests check how thick the coating is and how well the paint sticks to the surface.

Types of Powders Used in Powder Coating

Different powders are used for coating aluminum, and here are the main types:

Epoxy Powders

These powders stick well to surfaces and are resistant to chemicals, impacts, and abrasions. However, they can discolor and become chalky when exposed to Lumière UV. They’re great for things like appliances, cars, and industrial use.

Polyester Powders

These powders are good for outdoor use because they resist UV rays and weather. They keep their color and gloss over time. They are ideal for outdoor furniture, car parts, and other items exposed to the weather.

Polyurethane Powders

Combining the benefits of polyester and epoxy, these powders offer strong chemical resistance and UV protection. They’re commonly used for heavy machinery, buildings, and automotive parts.

Acrylic Powders

Known for their color clarity and smooth finish, acrylic powders also resist UV light. They are used in applications like furniture, electronics, and automotive finishes. While not as long-lasting as polyurethanes or epoxies, they still offer a good finish.

Hybrid Powders

These are a mix of polyester and epoxy resins. They combine the best features of both, offering good adhesion, weather resistance, and lower cost. They’re used for interior items like office furniture and industrial products.

Flouropolymer Powders

These powders are highly resistant to chemicals and weather. They’re ideal for use in tough environments, such as building facades, window frames, and outdoor parts that need to stand up to UV rays and weathering.

TGIC Polyester Coatings

TGIC is a special type of powdered polyester coating. It’s known for its strength, weather resistance, and UV protection. These coatings are great for outdoor applications and provide a glossy finish that lasts. They also resist chemicals and are flexible enough to handle heat expansion without cracking.

Nylon Powder Coating

Nylon coatings are durable and resistant to wear and tear. They reduce friction and are often used on items like kitchen utensils, gears, and bearings. They are also resistant to chemicals and are commonly used in automotive and industrial settings.

Antimicrobial Coatings

These coatings stop bacteria, fungi, and other germs from growing on surfaces. They’re used in places like hospitals, food processing plants, and public areas where cleanliness is important. They help reduce the need for frequent cleaning and improve safety.

Advantages of Aluminum Powder Coating

Here’s why aluminum powder coating is a great option for you:

• You can make your aluminum look better by adding different colors, textures, and designs.
• You don’t need to use strong-smelling or harmful chemicals during the curing process.
• Any extra powder that doesn’t stick can be collected and used again, so you don’t waste material.
• The coating you get is strong and long-lasting.
• It helps your aluminum resist rust and corrosion.
• The curing time is short, so the process is faster.
• Your coated parts will be more resistant to scratching and wear.
• It’s better for the environment because you don’t need to use liquid solvents.

Challenges When Powder Coating Aluminum

Even though powder coating aluminum has lots of benefits, there are some things you should think about before choosing it.

• It can be expensive because the aluminum powder coating machine costs a lot.
• You might see small differences in aluminum powder coating color between parts.
• Sometimes, thin lines called filiform can appear near the joints.
• The surface might look bumpy, like an orange peel effect.
• In some cases, the coating may not stick well.
• Over time, the color might fade or turn white, which is called chalking.

Powder Coating Aluminum vs. Painting Aluminum vs. Anodizing Aluminum

If you’re confused about which one to choose from powder coating, anodizing, or painting your aluminum parts, this might help you:

Revêtement par poudre

Powder coating is a strong and durable option. It resists wear, corrosion, and impacts better than paint. It’s quick to apply and cost-effective. Powder coating is also better for the environment because it doesn’t release harmful chemicals into the air, and the overspray can be recycled. However, it’s thicker and not as even as anodizing.

Peinture

Painting is cheaper and easier to do yourself. It offers more color options but doesn’t last as long as powder coating. Paint can chip and wear down quickly, so you might need to repaint more often. It’s also less durable overall and releases harmful chemicals into the air, which isn’t great for the environment. Painting also takes more time than powder coating.

Anodisation

Anodizing gives aluminum a thin, even coating that is really resistant to wear, scratching, and corrosion. It’s great for hard-to-reach areas and offers excellent protection. Anodizing is tougher than powder coating, but it is not as thick, so it doesn’t protect as well from high impacts. It’s also more expensive and not as widely available as powder coating.

What is the Ideal Thickness for Aluminum Powder Coating?

The thickness of aluminum powder coating is usually between 60 and 80 microns. The right thickness depends on how you’ll use the part, where it will be, and how strong it needs to be.

Factors Influencing Thickness

When choosing the coating thickness for your aluminum parts, consider the following:

Application Type

If you’re coating parts like machines or tools that deal with a lot of wear, hits, or rust, go with a thicker coating, about 100 to 150 microns. This gives you better protection.

When you’re working on things like window frames or outside walls, a coating between 60 and 120 microns usually works well. It keeps your parts strong and still looks good.

If you’re coating furniture or home appliances, a thickness of 50 to 100 microns is a good choice. It gives you enough protection while keeping the look clean.

Exposure to the Elements

If your parts are going to be outside in the sun, rain, or pollution, you should use a thicker coating to protect them from damage.

For parts that stay inside, you can use a thinner coating since they don’t face as much stress.

Meeting Performance Standards

If you want to stop rust, go thicker. A thick coating helps block out moisture and air. A thicker coating also helps your parts last longer by standing up to scratches and wear.

How to Measure Coating Thickness

To measure the thickness of your aluminum powder coating, you can use a few different tools.

Magnetic thickness gauges are common for magnetic surfaces, but since aluminum isn’t magnetic, you’ll want to use eddy current gauges instead. These are made for non-magnetic métaux like aluminum and give you accurate results without damaging the surface.

You can also use micrometers to measure the total thickness, then subtract the thickness of the aluminum to find the coating thickness. No matter which method you use, it’s important to apply the coating evenly and cure it properly. Uneven coating or poor curing can lead to weak spots, poor adhesion, and a shorter lifespan.

Real-World Applications of Powder-Coated Aluminum

Below are some real-world examples where powder-coated aluminum parts are used:

Industrie automobile

In the automotive industry, powder-coated aluminum is important for parts like wheels, engine components, and trim. Alloys such as 6061 are preferred because they are strong, light, and resist corrosion. For example, 6061 is used in car wheels to make them lightweight and durable.

Architecture

Powder-coated aluminum is also used in building materials like window frames, panels, and facades. Alloys such as 3003 and 5052 are used here because they are easy to shape and can resist weather, which helps keep the buildings looking good and strong over time.

A good example is the Louvre Abu Dhabi, where powder-coated aluminum helps the building’s design last longer.

Industrie aérospatiale

The aerospace industry uses powder-coated aluminum for parts that need to be precise and strong. Alloy 7075 is popular here because it’s tough and can handle the extreme stress that aircraft parts face. It’s used in airplane frames, ensuring they stay safe and durable even under tough conditions.

Conclusion

Powder coating is a durable, corrosion-resistant finish that enhances the look and protects almost any aluminum product, regardless of application. At DEK, we’ve helped many customers with powder-coated aluminum products, and we can help you too! Upload your designs now, and get a free quote.