Anodizing, Powder Coating, Electrophoresis, How to Choose?
Recently, we received couples of enquires about post finish selection. Some customers want to make custom metal parts look pretty. They are entangled in how to select the suitable finish at low cost but high quality, maybe anodizing service? There are various methods you can use to apply coating to various aluminum alloys. These methods include anodization, powder coating, and electrophoresis. Each method has its own uses in various circumstances. Sometimes, you will need to use a certain coating method, while other times, you might choose any coating method that will suit your preferences the most. Here, we want to share our experiences and opinions about Powder Coating, Anodizing, Electrophoresis finishes.
1. Powder Coating
Powder coating is a type of coating that is applied as a free-flowing, dry powder. The main difference between a conventional liquid paint and a powder coating is that the powder coating does not require a solvent to keep the binder and filler parts in a liquid suspension form. The coating is typically applied electrostatically and is then cured under heat to allow it to flow and form a "skin". The powder may be a thermoplastic or a thermoset polymer. It is usually used to create a hard finish that is tougher than conventional paint. Powder coating is mainly used for coating of metals.
Powder coating is commonly used to coat aluminum alloy. With this coating process, you can put an additional layer containing thick aluminum powder on the aluminum’s surface. By doing that, you can make the aluminum material more durable and more resistant to corrosion. This process is quite simple to do, but it can get complicated if you encounter some problems with the resulting powder-coated aluminum material.
Pros
● Cost-effectiveness in the long run.
The powder coating process might have a higher initial cost, but it is quite cost-effective in the long run. After purchasing the equipment, it won’t be as expensive to run the regular powder coating process.
● Better durability.
With powder coating, you will turn the aluminum material into a more durable one. In this process, you will need to apply quite a lot of aluminum powder, which will lead to providing better durability for the base aluminum alloy.
● No waste material.
With the powder coating process, you don’t need to worry about waste materials from this process. There’s little to no waste materials produced from the powder coating process. All the aluminum powders will adhere to the surface area of the aluminum material, leaving no waste material behind.
● Better scratch and corrosion resistance.
The thick powder coating material for the aluminum alloy will provide the aluminum material with a better scratch and corrosion resistance. So, this is the coating process that will provide you with the best solution to reduce or eliminate scratching and corrosion on the aluminum alloys.
● Healthy for the environment.
Powder coating is an aluminum processing method that doesn’t produce much waste materials, which means it is healthy for the environment. Also, this process doesn’t cause any pollution in the air, as the resulting VOCs (Volatile Organic Compound and Smog) stay in the powder coating booth equipment.
Cons
● Unable to apply thin coating.
With powder coating, you need to apply thick coating for the aluminum material. You can’t apply thin coating on it, as the aluminum material won’t be able to absorb enough powder on the aluminum surface. Thus, a large amount of aluminum powder is necessary for the powder coating application.
● Difficult to change color.
You can’t change the coating color with ease. Yes, it is possible to change the coating color, but you will need to remove the previous powder-coated surface first before you can apply a new coating color with the powder coating process. This process can be daunting and complicated to do.
● Uneven finish.
With powder coating, sometimes you will need to deal with uneven finishing, which means the coloring of the surface won’t spread to all the surface areas of the aluminum material. Also, you can’t just add new powders to the uneven areas to fix this problem.
● Higher start-up costs.
To perform the powder coating process, you will need to have certain powder coating equipment ready. The costs of purchasing the equipment will be quite expensive, as you will need to buy the powder coating oven, powder coating booth, and spray gun to perform the powder coating process, along with the aluminum materials and powder coating materials you need to prepare.
2. Anodizing
Anodize (also spelled anodizing, particularly in the UK and Australia) is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts. Aluminum alloys are anodized to increase corrosion resistance and to allow dyeing (coloring), improved lubrication, or improved adhesion. Anodizing produces a very regular and uniform coating. Some aluminum aircraft parts, architectural materials, and consumer products are anodized.
Anodized aluminum is the type of aluminum material that has undergone the anodization process, which is an electrochemical process that transforms the metal surface of the aluminum material with the anodic oxide surface finish. Aluminum anodizing can be found on smart phone, multi-tools, flashlights, anodized aluminum cookware, cameras, sporting goods, window frames, in electrolytic capacitors, and on many other products both for corrosion resistance and the ability to retain dye. The anodic oxide surface has a more metallic appearance, and it is also useful as a decorative property for the anodized metal. Also, with this process, you can increase the thickness of the aluminum surface, improving its overall durability.
Pros
● Stronger aluminum build.
The aluminum anodizing process provides the base aluminum alloy with a stronger build, meaning that you can improve the overall durability of the aluminum metal such as hard anodized cookware after this process. Also, you will give the base aluminum metal with more appealing metallic anodizing colors.
● More resistance to wear and corrosion.
You can provide the aluminum alloy with more resistance from corrosion and regular wear by adding a new metallic layer via the anodized aluminum process. It will be very useful for various applications, such as construction and home appliances anodized cookware.
● Better surface finishes.
Anodization can also create better surface finishes for the aluminum, and you can apply various colors to the aluminum surface later. The smoother surface of the aluminum, along with its metallic appearance, makes the anodized aluminum a much better option compared to the regular one.
● Prevent peeling or flaking on the aluminum surface.
Anodizing aluminum is a process that alters the material’s surface. So, the resulting surface finish will become integrated with the base aluminum metal itself, anodized meaning that you don’t need to worry about peeling or flaking on the aluminum surface.
● Easier maintenance.
With the smoother metallic surface, you can maintain the hard anodized aluminum material even easier than regular aluminum. For instance, to keep its metallic color in its best appearance, you can just clean the aluminum surface with detergent and water.
Cons
● Lower thermal conductivity.
The anodization process will make the aluminum material lessen its thermal conductivity. Anodized aluminum is excellent as an insulator, but it is not good for you to use it as a material to transfer heat. Also, cracking might happen especially in black anodized aluminum when exposed to high temperatures.
● Inconsistent results.
The anodization especially the hard-anodized process will not have a consistent result between batches. So, you can only maintain consistency in the result of each batch. You will have discrepancies in the anodize aluminum results for the different batches you are working on.
● Higher costs of production.
Anodizing process requires you to use higher-grade aluminum alloys especially for the clear anodized aluminum, which are quite expensive. The reason is that only aluminum alloys with higher grades can withstand the anodization process. Thus, it makes the overall production costs more expensive when compared to other processes.
How to Anodize Aluminum Parts
Anodizing is a common process you can do for aluminum materials, and the primary goal of this process is to improve the corrosion resistance and durability of the aluminum materials. You can also apply anodizing for the aluminum parts that you have manufactured in your production process.
Anodizing for aluminum parts involves the process of using the anodizing equipment to improve the corrosion-resistance properties of the aluminum parts. You will need to use the electrolytic bath and the electric currents to start the anodizing process of the aluminum parts.
The anodizing process will help create a new layer on the aluminum surface, which will help improve the corrosion and abrasion resistance of the aluminum parts, along with other benefits.
Anodizing Aluminum Parts - Step by Step
Anodizing aluminum parts involves submerging the aluminum parts into the electrolytic bath and delivering electric currents to the electrolytic bath. Here’s the step-by-step process to anodize aluminum parts:
1. Preparing the aluminum parts.
The first step is to prepare the aluminum parts you would like to get anodized. Prepare the number of parts you would need to get anodized and how you would like to perform the anodizing process, such as by categorizing them.
2. Pre-treating the aluminum parts.
The aluminum parts that are fresh out of production will have a certain level of “uncleanliness”, which requires you to clean them before the anodizing process. Some aluminum parts might have the residue from heavy metals and other stuff that can disrupt the anodization process. This is the reason you need to apply a pre-treatment to the aluminum parts, such as by applying the bright or satin finish or by degreasing them.
3. Preparing the anodizing equipment.
The equipment for anodization will contain the electrolytic bath, and you can anodize the aluminum parts by submerging them into the bath. You will need to prepare the anodizing equipment first and make sure that it is ready to use. You need to configure the equipment as necessary.
4. Submerging the aluminum parts into the electrolytic bath.
Once you have prepared the anodizing equipment, which contains the electrolytic bath, it is time for you to submerge the aluminum parts into the electrolytic bath. Be sure to line up the parts well, so that you can fit as many parts as possible in one anodizing process.
5. Delivering electric currents to the electrolytic bath.
Now that the aluminum parts are submerged, you can deliver electric currents to the electrolytic bath and start the anodizing process. Depending on the number of parts you are working on, the anodizing process can take some time, between a few minutes to a few hours.
6. Completing the anodizing process.
After waiting for some time, the anodization process will complete. The next step is to take out the anodized aluminum parts from the electrolytic bath and prepare them for the next step.
7. Coloring process (optional step).
After completing the anodizing process, you can put the aluminum parts into another process, which is coloring. This is an optional process, but you can apply different colors to your aluminum parts if you want it. Also, applying different colors can create uniqueness for the parts and improve their aesthetic looks.
8. Sealing process.
Another process is the sealing process. This process can help you with preventing corrosion and leakage for the aluminum parts, in case you will use the parts in specific environmental conditions. There are two basic sealing methods, namely the hot method and the cold method.
9. Quality checking.
You have completed the anodization process, and the parts are ready to be packaged and delivered. But before that, it’s important for you to check for the quality of each aluminum part before sending them to your clients or customers.
Important Benefits of Aluminum Parts Anodizing
Anodizing can give you plenty of benefits, especially if you are looking to improve the overall quality of the aluminum parts. It is quite a simple process, but you can get various long-term benefits out of this simple process. Here are some important benefits of aluminum parts anodization:
●Improved corrosion and abrasion resistance.
Aluminum parts might already have some corrosion-resistance properties, but with anodization, you can improve the corrosion-resistance properties of the aluminum parts significantly. Also, you can use anodizing to make the aluminum parts immune from abrasion, so you don’t need to worry about scratching the surface of the aluminum parts when you apply any friction to it.
●Possibility to apply different colors as decorations.
Anodized aluminum parts will also be easier for you to colorize later. You can apply different colors for the anodized aluminum parts to decorate the surface look of the parts, improving their appearance.
●Improved aesthetics.
Another benefit of anodization for the aluminum parts is that this process will improve the overall aesthetics of the part’s surface, even when you don’t apply any additional coloring to it. The regular aluminum might have a “bland” color look to it, while anodized aluminum will have a more metallic look, which is better in terms of the overall aesthetics.
●Resistance to daily wear and tear.
You might need to use the aluminum parts for various daily operations in various industries, such as automotive, consumer electronics, and more. The good thing about anodized aluminum parts is that it will be resistant to the daily wear and tear. So, you can expect the aluminum parts to keep its excellent aesthetics for a long time, even when you use them for daily operations.
●Improved durability for long-term use.
The anodizing process can also improve the durability of the aluminum parts for long-term use. Thus, when you use this process, you can ensure that the aluminum parts can still function as normal inseveral years, or even10 years after you use it for the first time.
Powder Coating vs. Anodizing - Several Aspects of Differences
1. Powder Coating vs. Anodizing: Coating Consistency
The problem with powder coating is often its coating inconsistency. Sometimes, you will find uneven coating around the material’s surface when you use powder coating. Meanwhile, with anodizing, the coating is even and consistent on the material surface. This is because you are submerging the material into the electrolytic chamber to achieve this result.
2. Changing the Coating Color
With anodizing, it will be quite simple for you to change the color of the coating you put on the material surface. However, it is not so with the powder coating method. Once you have applied a certain color with powder coating, it will be difficult to change the coating color.
3. Surface Finish Quality
Anodizing can provide you with a much better and more polished surface quality. Meanwhile, powder coating will sometimes give you rough coating areas on the material surface. This is mostly because of the electrolysis process used in anodization, which makes the surface materials look shiny, smooth, and polished as a result.
4. Potential Coating Damage
With powder coating, you might damage the coating over time because of various reasons. In certain environmental conditions, the powder coating might get peeled from the surface material. This can damage the overall look of the aluminum material, which is not preferable. Meanwhile, anodization can show a more consistent surface coating with minimum chance of damage during long-term use.
5. Powder Coating vs. Anodizing: Resistance to Wear and Corrosion
With anodization, you can get a much better resistance to wear and corrosion because of the thorough electrolysis process applied to the material. Meanwhile, the powder coating method doesn’t give you too much improvement in the corrosion and wear resistance of the material.
Important Key Points
● For a more advanced result, anodizing is the best choice you can use for the coating process of aluminum materials.
● Powder coating offers simplicity of application, whereas anodizing requires you to do a lot of preparations before applying the coating process.
● Anodizing offers more durability for the coating, which is best suited for long-term use.
3. Electrophoresis
Electrophoresis is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric field. The technique applies a negative charge, so proteins move towards a positive charge. It is ultimately caused by the presence of a charged interface between the particle surface and the surrounding fluid. Electrophoresis can be aluminum coating process, which requires you to submerge the aluminum material, along with the coating material, into the liquid solution charged with electric currents. The electrophoresis process will go on for a few minutes, and during this process, the coating material will adhere to the surface of the aluminum material, resulting in metallic color finish.
Pros
● Higher impact resistance.
When compared to anodization, electrophoresis can provide the aluminum material with a higher impact resistance. The reason is that it applies the coating process with the higher hardness level for the aluminum alloy.
● Quick process.
With electrophoresis, you just need to immerse the aluminum alloy and the coating material in the liquid solution and charge it with electric currents to start the process. It will only take a few minutes before you can see the resulting coated aluminum alloy.
● Better wear and chemical resistance.
With better durability and higher impact resistance produced by electrophoresis, you can have better wear and chemical resistance for the aluminum alloy. When compared to anodization, electrophoresis can provide you with a much better chemical and wear resistance.
● High-adhesive surface coating.
The surface coating produced by the electrophoresis process will be high adhesive, which means a stronger surface coating for the aluminum alloy. The high-adhesive surface coating makes it very durable and difficult to fall off.
● Better corrosion resistance.
With a better coating, it means a better corrosion resistance for the surface finish. Aluminum alloys that have undergone electrophoresis can have much more resistance to corrosion when compared to anodized aluminum.
Cons
● Lower heat conductivity.
The resulting coated aluminum from the electrophoresis process will have lower heat conductivity, meaning that it is not suitable to use in applications that require high heat conductivity.
● Lower electrical conductivity.
The resulting coated aluminum will also have lower electrical conductivity, making it not suitable to use for applications that require high electrical conductivity.
● Requires higher grade aluminum alloys.
You can only use higher grade aluminum alloys for the electrophoresis process, which will allow you to produce thicker and more durable coating for them.
● Fewer color options.
There are only a few colors available for you to choose when using the electrophoresis process.
● Higher costs.
You will need to use a higher grade of aluminum alloys to perform this process, which can get very expensive for each production cycle.
Conclusion
Between anodized aluminum, powder coating, and electrophoresis, each has its own benefits and disadvantages. You can use the anodizing service if you want the best result in the rapid manufacturing for small volume production. This is the method that can provide you with coated aluminum alloys that have better durability, corrosion resistance, and high-impact resistance.
However, the two other methods can also provide you with various other benefits, such as cost effectiveness for large volume production. You can use these more affordable methods if your project doesn’t require you to use the best aluminum coating.
Contact TEAM Rapid
TEAM Rapid offers customize metal part fabrication and post finishing (anodizing service). We can make your parts at lower cost and better quality by our professional rapid prototyping service and die casting services. Furthermore, we provide the post finish service to meet your product needs. Are you working on your next rapid prototyping and pressure die casting project? Contact our team at [email protected] and get a free quote today.
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