Due to their desirable qualities, metals like aluminum, magnesium, titanium, etc., have been used in a variety of industries, including the automotive, aerospace, electronic, etc. However, these applications necessitate the use of these metals under risky working circumstances.
High humidity, high temperatures, the presence of acids and salts in a service environment, etc. are a few conditions that cause certain metals to lose some of their properties. This increases the cost of maintenance or component replacements by causing some metals to degrade under use.
Techniques have been devised to protect these metals when utilized in these conditions. One method for protecting these metals from risky working circumstances is anodizing. By enhancing the metals’ resilience, the price of component replacement and maintenance is reduced.
In this guide, we will take a look at what anodized aluminum is, how it is made, and the benefits of using it in your projects. We’ll also discuss the different types of anodizing and tips for designing with anodized aluminum. Finally, we’ll answer some of the most frequently asked questions about anodized aluminum.
If you have any questions, please contact us with any questions about our anodizing process or request a quote today.
What Is Anodizing?
Anodizing is an electrochemical process used to increase the thickness of the natural oxide layer on the surface of metals such as aluminum, titanium, and magnesium. This method improves the metal’s corrosion resistance, wear resistance, and aesthetic attributes. An appealing and long-lasting protective layer is made by anodizing onto the metal’s surface.
For years, anodizing has been used to protect and improve the appearance of aluminum. The procedure entails running an electric current through an acid electrolyte bath while the aluminum is submerged in it.
As a result, an armor-like oxide coating forms on the surface of the aluminum, oxidizing it. The oxide layer is useful for a range of applications since it is tougher and more corrosion resistant than the aluminum itself.
How Does Aluminum Anodizing Work?
Anodizing follows the same broad strokes as many other finishing processes. In practice, this means that you should follow this process:
- Prepare the surface
- Anodize
- Clean the parts
- Add color
- Seal the pores
Prepare
Before you anodize a part, you have to prepare its surface through mechanical and chemical means. To give your part the desired aesthetic, polish or bead blast the surface first. While brushing will give your part a brushed appearance, bead blasting will give it a natural matte finish.
Anodizing
Next, place the part or parts in the anodization bath connected to the electrical circuit. The parameters of the solution, such as its composition, temperature, current density, voltage, and time, might vary depending on the desired properties described above.
Clean the Parts
After anodizing, the component needs to be cleaned using solvents and deionized water. After, don’t forget to dry the component. By doing so, any excess solution is removed, and the component is prepared for the chromatic finish.
Color
You can control the component’s color during anodizing. The visible spectrum’s nanometer-sized wavelengths can reflect light in a variety of ways, depending on the thickness of the oxide coating. Several characteristics are used to produce a wide range of colors.
To give your part a bronze or black shine, submerge it in a solution of metallic salts. They interact with the surface to fill the pores with a bronze- or black-colored chemical compound. Electrolytic coloring is the name given to it.
Seal the Pores
To stop future corrosion and boost performance, you must seal the tiny pores on the component’s surface after anodizing. Anodized parts may feel tacky to the touch if the pores are not sealed. Furthermore, dirt, pollutants, and stains can gather in open pores.
Benefits Of Anodized Aluminum
Anodized aluminum is a popular choice for many applications due to its numerous benefits. Anodizing is a process in which aluminum is treated with an electrochemical process to create a protective layer on the surface.
This layer helps to protect the aluminum from corrosion and wear while also providing a decorative finish. Anodized aluminum is highly durable, lightweight, and cost-effective, making it an ideal choice for many projects.
Corrosion Resistance
Aluminum that has been anodized is more corrosion-resistant than plain aluminum. Both regular and anodized metal cannot rust. Yet, they still have the potential to corrode when exposed to moisture, air, salt, or other substances or elements that prevent corrosion. Yet, because anodized aluminum has a thicker layer of oxide than ordinary aluminum, it is less likely to corrode.
Appearance
Appearance is one of the main reasons why anodized aluminum is so popular. Anodized aluminum has a unique look that is both attractive and durable. The anodizing process adds a protective layer to the aluminum, which gives it a glossy, metallic finish. This finish can be customized to create any look imaginable, from a matte finish to a bright, vibrant color.
Anodized aluminum is also resistant to fading and discoloration, so it will remain looking great for years to come. Anodized aluminum is also a great choice for projects that require a specific color or finish, as it can be tailored to match any desired look. Anodizing aluminum also helps protect the surface from scratches and other damage, making it a great choice for areas exposed to the elements.
Custom Color Options
Custom color options are an important consideration when choosing an anodized aluminum product. Anodizing aluminum allows for a variety of colors to be achieved, giving the product a unique look and feel. With anodizing, the color of the aluminum is determined by the thickness of the anodized layer. The thicker the layer, the darker the color. The process also allows for a wide range of colors, including black, red, blue, green, and yellow.
Anodizing aluminum also gives the opportunity to create custom colors. Through the use of dyes, the anodized aluminum can be given any color desired. This is a great option for businesses or individuals looking for a unique look for their product. The dyes are mixed with the anodizing solution and then applied to the aluminum. The color is then sealed in with a clear top coat to ensure the color stays vibrant for years to come.
Light Weight
Compared to other metals, anodized aluminum is a lightweight material with a lot of benefits. Its small weight makes it the perfect choice for applications where weight is a primary consideration, yet strength and durability are crucial.
Due to its less weight than steel (around one-third), anodized aluminum is much simpler to carry and install. It is a fantastic option for outdoor applications because it is also very corrosion-resistant.
Furthermore, non-magnetic, anodized aluminum is appropriate for use in delicate applications such as electrical components. It is the perfect option for a number of applications, from consumer goods to architectural projects, because to its low weight and durability.
Cost
Anodizing aluminum is a cheap option in terms of price. Aluminum may be anodized easily and without the use of any specialized tools or machinery. When compared to other methods of metal treatment, anodizing aluminum has a relatively cheap cost.
Anodizing aluminum can range in price from a few cents per square foot to a few dollars per square foot, depending on the size and intricacy of the operation.
The type of anodizing technique utilized affects how much it costs to anodize aluminum. For instance, Type I chromic acid anodizing is the least expensive type of anodizing, but Type III hard coat anodizing is the most expensive.
The size and complexity of the job also affect the cost of anodizing aluminum, as more intricate designs and larger pieces require more time and labor to complete. The thickness of the coating can also affect how much anodizing aluminum costs because thicker coatings need more labor and resources.
Increased Adhesion
Lastly, anodized aluminum has better adhesive and primer adherence. This is a result of anodized aluminum’s oxide surface having larger holes than ordinary aluminum.
When adhesive, primers, or liquids are applied to the surface, they will flow into the pores, which are essentially holes. Greater adhesion is possible thanks to the anodized aluminum’s ability to absorb liquids.
Uses Of Anodized Aluminum
Anodized aluminum is a versatile material that is used in a wide variety of industries and applications. It is used in architecture, transportation, consumer goods, and more. Anodizing aluminum provides a durable, corrosion-resistant finish that is also aesthetically pleasing.
Architecture
Architectural anodized aluminum is popular for commercial and residential projects due to its durability, lightweight, and aesthetic appeal. A number of products, such as window frames, siding, railings, and more, employ anodized aluminum. In addition, it is employed in the development of buildings, bridges, and other constructions.
Aluminum is a great material for outdoor applications since anodizing helps to protect it from corrosion and wear. A layer of aluminum oxide is formed on the metal’s surface during the anodizing process, making it incredibly resistant to abrasion, weathering, and corrosion. Also, this additional layer of defense keeps the aluminum looking beautiful for many years to come.
Transportation
One of the most significant industries that uses anodized aluminum is transportation. From automotive to aerospace, anodized aluminum is used in a wide range of transportation-related applications.
Anodized aluminum is used in the construction of aircraft, helicopters, missiles, and satellites in the aerospace sector. Due to its reduced weight than steel and other metals, anodized aluminum is a great material for spacecraft and airplanes. Anodized aluminum is a wonderful option for components that will be exposed to the environment because it has excellent corrosion resistance.
Anodized aluminum is used in the construction of cars, trucks, and other vehicles in the automotive sector. Vehicle frames, motors, and other parts are all made of anodized aluminum. Since anodized aluminum is lighter than steel and other metals and offers the best corrosion resistance, it is also used to create automotive wheels.
Consumer Goods
Consumer goods are a broad category of products that are used by individuals in their everyday lives. Because of its strength, lightweight, and appealing look, anodized aluminum is a common material for consumer goods. From electronics and appliances to furniture and jewelry, anodized aluminum is utilized in a wide range of consumer items.
In the same vein, electronics and appliances are also often made of anodized aluminum because of their strong and lightweight properties. From laptop and tablet cases to cell phones and gaming consoles, anodized aluminum is used in a wide range of consumer devices.
Kitchen equipment like toasters, blenders, and food processors also employ anodized aluminum.
Different Types Of Anodizing Aluminum Process
Anodizing aluminum is a process used to increase the thickness of the natural oxide layer on the surface of the metal. This layer provides protection from corrosion and wear, and can also be used to give the metal a decorative finish. Anodizing is typically done in three different types, each with unique properties and benefits.
Types Of Anodizing Process And Uses
The type of anodizing processes and uses are as follows:
Type I
Chromic acid anodizing is primarily used to safeguard crucial joints and structures. The corrosion resistance is excellent, given the coating’s thickness, which is typically between 0.08 and 0.2 mils. The created oxide film is manufactured without suffering from considerable material fatigue loss and is softer and less porous than those made using the other methods. The hue is a pale opaque gray, and the film is easily damaged. This film takes on a greenish tint after being sealed with a dichromate seal.
Depending on the kind given, the procedure is voltage controlled and starts with a ramping increase up to 40 volts. The two types that are listed under the military specification MIL-PRF-8625F are Type I and Type IB. Type I generates conventional coatings at a voltage of about 40 volts, whereas Type IB operates at a voltage of 20 to 22 volts.
When Is It Used?
Chromic acid anodizing is a metal coating process used when the application calls for a thin coating and high corrosion resistance. An aluminum component is submerged in a chromic acid bath during a chemical conversion procedure to produce a Type I coating.
Type II
Type 2 anodizing, also referred to as sulfuric acid anodizing, is the most popular anodizing method. Changing an aluminum substrate material’s surface produces an aluminum oxide protective coating.
It works well in circumstances where a high degree of hardness and abrasion resistance are required.
Sulfuric acid anodize can also be used to boost surface corrosion and protection in severe working conditions or as a base for paint systems. Using the porous nature of sulfuric acid coatings before sealing, in particular, allows for the production of colored surface finishes on aluminum and similar alloys.
When Is It Used?
Sulfuric anodizing is widely used across all industries for general and commercial aluminum anodizing.
The military standard MIL-A-8625 is most frequently used as the foundation for Type II coating. This designation is a global industry standard for commercial use in the aerospace, automotive, and medical sectors, in addition to military and defense applications.
Type III
Hard anodizing, also known as type III aluminum anodizing or hard coat anodizing, is used to increase the thermal and mechanical qualities of treated aluminum goods as well as their resistance to wear and corrosion. Furthermore, Type III anodizing enhances the ability to hold onto lubricants and PTFE coatings (such as Sanford HardlubeTM).
With hard coat anodizing, the thickness of the oxide layer that is already present naturally on aluminum surfaces is increased. Natural oxide layers, which are normally 2 to 3 nanometers thick, can be increased to or even above 50 m with Type III anodizing (0.002″). The treated object’s whole surface is covered in a regular, homogeneous layer by strategically placing hard anodic coatings.
The military standard Mil-A-8625 Type III category gave rise to the abbreviation Type III anodizing. * μm = micrometer (1000x the length of a nanometer).
When Is It Used?
It is used whenever the application calls for a super hard surface. The process is similar to Sulfuric Anodizing, but the layer of aluminum oxide is produced at much higher voltage and cooler temperatures..
Tips For Designing Anodized Aluminum
When designing a product produced with anodized aluminum, there are a few tips to keep in mind to ensure the best results. Anodizing aluminum is a process that requires precision and skill, and understanding the basics of the process can help you create the best product possible.
Watch Out For Tolerances
Tolerance is an important factor to take into account when constructing a product with anodized aluminum. It is described as the allowable variation in the size and shape of a product It could be challenging to obtain the ideal finish if the tolerances are too tight.
While creating a product, it’s crucial to take tolerances into account because anodizing can cause aluminum to slightly expand and contract when subjected to heat or cold. As a result, the metal may warp and the product’s quality may suffer.
It is advisable to allow for a little extra space in the design to allow for any movement of the aluminum.The anodized aluminum may crack or chip if the tolerances are too tight, which can be challenging to fix. While planning for anodizing, it’s crucial to consider the product’s dimensions. It can be more challenging to produce an even finish on larger products. It is best to keep the design as straightforward as possible to maintain a uniform finish.
Edges And Corners
When designing for anodizing aluminum, it is important to consider the edges and corners of the material. As anodizing is an electrochemical process, any sharp edges, corners, or crevices can cause uneven anodizing, resulting in a less-than-desirable finish.
To ensure a uniform anodized layer, it is essential to make sure all edges and corners are rounded off and smooth. If a design has any sharp edges, these should be rounded off using either a file or a grinding wheel. It is also important to keep in mind that the anodizing process will make the material slightly thicker, so any tight tolerances should be adjusted accordingly.
Consider Using Other Finishing Steps
When it comes to anodizing aluminum, it’s important to consider using other finishing steps to maximize the performance and aesthetic of your product. A few of the most common finishing steps used in conjunction with anodizing aluminum include masking, brushing, etching, and passivation.
Masking is the process of covering certain areas of aluminum to prevent them from being anodized. This is often done to keep certain areas from being colored or to protect them from the anodizing process. Masking can be done with a variety of materials, including tape, paper, plastic, and rubber.
Final Thoughts
The use of anodized aluminum is a great way to protect and enhance the appearance of aluminum products. To achieve a better product, aluminum can be anodized to produce a variety of colors and finishes, as well as better durability and corrosion resistance. For many applications, it is also a lightweight, affordable solution.
Furthermore, aluminum can be easily anodized, and the procedure can be completed quickly and effectively with little downtime. An elegant, long-lasting finish can be achieved with anodized aluminum if the correct design factors are taken into account.
Understanding the fundamentals of anodizing aluminum can help you make the most of this flexible process and produce an attractive and long-lasting item. Architectural and consumer goods alike can benefit greatly from the use of anodized metal. Anodized aluminum might be the ideal choice for your project with careful planning and the proper design.
Equally important is the finishing company where the aluminum was anodized. Using aluminum anodized by highly professional and certified metal finishing companies is important.
At Valence, we take care to ensure your parts are flawless. We offer a range of inspection services, including NDT as a standalone service and all pre- and post-NDT finishing services.
With multiple in-house level 3 certified technicians, we expertly process everything from small parts to large structural parts up to 30’. Our technicians complete exceptional training and exceed standards throughout the entire production process.
If your business needs functional aluminum parts that will face corrosion or wear, such as aircraft parts or consumer goods, contact us or request a quote, and we’d be more than happy to help.
FAQs
How much does anodizing cost?
The cost of anodizing aluminum varies depending on the size, type, and thickness of the aluminum being anodized and the type of anodizing process being used. Generally, anodizing can cost anywhere from $0.50 to $5.00 per square foot.
Does anodizing wear off? How long can it keep?
Anodizing is a very durable finish and can last for decades with proper care. The finish is resistant to wear and tear, as well as corrosion and UV damage. However, it is not completely indestructible and can be scratched or damaged with enough force.
Does anodized aluminum rust?
No, anodized aluminum does not rust. Anodizing is a process that creates an oxide layer on the aluminum, which seals the surface and prevents corrosion.
How can you tell if aluminum is anodized?
Anodized aluminum has a distinctive look and feel. It is usually darker than regular aluminum and has a slightly rough texture. You can also tell if aluminum is anodized by running a magnet over it. Anodized aluminum is non-magnetic, while regular aluminum is magnetic.
Is anodized aluminum better than aluminum?
Anodized aluminum has many advantages over regular aluminum, including increased durability, improved appearance, and better corrosion resistance. Anodized aluminum is also lighter than regular aluminum, making it more suitable for certain applications.
Is anodized aluminum harmful?
Anodized aluminum is not harmful to humans and is considered safe for food contact. The anodizing process does not use any toxic chemicals, and the finished product does not contain any hazardous substances.
Which is healthier, stainless steel or anodized aluminum?
Both stainless steel and anodized aluminum are considered safe for food contact and are not known to cause any health problems. However, stainless steel is slightly more durable and corrosion-resistant than anodized aluminum, making it a better choice for certain applications.