Month: October 2024

Read Part 1 and Part 2 of our three-part series The Difference Between Chem Film vs. Anodize here!

In the final part of our series on the difference between chem film vs. anodize, we delve into the practical applications and industries that benefit from these metal finishing techniques. Both chem film and anodizing offer unique advantages, making them suitable for a variety of uses across numerous sectors. From aerospace and automotive to electronics and consumer goods, the choice between chem film and anodize can significantly impact the performance and longevity of metal components. This blog will explore specific examples highlighting how each finishing method is employed in different industries. 

Chem Film vs. Anodized Finishing 

While chem film uses only a chemical process, anodization entails the use of electricity as well as chemicals. Chem film finishing usually entails just submerging aluminum components into a chemical bath at room temperature, though the chemical solution can instead be brushed or sprayed onto components. After a few minutes, these chemicals create a thin protective layer on metal surfaces made up mainly of chromium oxide, after which components are rinsed and dried. Though soft initially, the chem film finish becomes harder as it dries. However, chem film finishes won’t ever be as strong as anodized ones. Though these finishes have their place, especially in applications requiring electrical conductivity, chem film coatings have their limitations.

When comparing chem film vs. anodized metal coatings: 

• Color: Though really just an aesthetic issue, the differences between chem film vs. anodized coatings for decorative applications also give the latter treatment an advantage. Though both treatments allow clear finishes, non-transparent chem film coatings can only be made in a sort of copperish color. While chem film treatments accept paint or powder coatings well, this entails an additional process. Anodized finishes can be dyed in all sorts of different shades.
• Durability: Comparisons between chem film vs. anodized finishes prove the former to be much less durable. Chem film’s relatively soft and thinner coatings are easily scratched or otherwise damaged, which is why it’s often considered an impermanent finish. Chem film finishing is commonly done for prototypes rather than mass-produced parts that must withstand wear or abrasion. Anodized coatings protect surfaces better as they’re harder and thicker.   
• Lubricity: One of the significant differences between chem film vs. anodized coatings involves friction. Chem film finishes enable better adhesion to the surface, while anodized surfaces slide more easily, a plus for parts designed to interact with other parts. For this reason, most mechanical components will have anodized rather than chem film finishes. Additionally, fewer contaminants will adhere to anodized surfaces as they have better lubricity, making them easier to clean than those finished via chem film.

For manufacturers looking to finish their components themselves, chem film is the better option, as it’s quicker, easier, and less costly. Anodization is a complex process that requires considerable expertise and extra infrastructure, often done by specialist third-party providers. Yet, chem film may be the better option as an intermediary step for finishing or for temporary protection, as is the case with prototypes. For components needing tight tolerances, chem film coatings are thinner, so it may be more desirable as they won’t change a part’s dimensions, as anodized finishes are generally thicker.

Industries That Use Chem Film & Anodized Metals

Both chem film and anodized finishes are used across almost all industries for nonferrous metal components. These two techniques are sometimes even used for the same types of products, though the unique qualities each gives to metals often make one method better for specific applications. 

The following industries use chem film and/or anodized metal finishes: 

• Aerospace: Anodized components are used to ensure enduring durability and resistance to corrosion, while anodization also reduces friction between moving parts; chem film finishes are used for parts that are less exposed to the elements but require greater precision as chem film layers are slightly thinner. 
• Architectural: Due to its superior aesthetics, anodized aluminum makes a better fit than chem film for such applications, which is often used to protect decorative architecture against exposure to the elements.
• Automotive: Anodizing is often used for both aesthetic and durable finishes for vehicles, especially exterior components.
• Defense: For military equipment, both processes reduce the shininess of aluminum, keeping items from standing out on the battlefield; however, when comparing chem film vs. anodized coatings, the latter offers better corrosion resistance on its own than chem film coatings, which would require secondary coatings for similar protection. 
• Electronics: Both chem film and anodization finishes are helpful for electronic products, the former when electrical conductivity is needed and the latter when electrical insulation is required.
• Marine: Since anodization withstands corrosive conditions better, anodized finishes are more durable for saltwater applications than chem film finishes.

When considering chem film vs. anodized coatings for parts or products, these are some of the most vital factors to consider. In a nutshell, anodization is generally the better option as a longer-lasting finish, due to its better corrosion and wear resistance. However, parts undergoing a secondary treatment like painting or powder coating may be better suited to chem film coatings. Additionally, chem film finishes offer better electrical and thermal conductivity, while anodized ones provide better insulation against electricity and heat.

To learn more about our metal finishing and plating solutions, including chem film and anodizing, contact the experts at Silvex, Inc. today!

Read Part 1 of our three-part series The Difference Between Chem Film vs. Anodize here!

Continuing our exploration of metal finishing techniques, the second part of our series focuses on anodizing, a popular method used to protect and enhance the surface of aluminum parts. Anodizing not only improves corrosion resistance but also allows for the addition of vibrant colors and increased surface hardness. In this segment, we will take a closer look at the process of anodizing metal. By the end of this blog series, you’ll have a comprehensive understanding of chem film vs. anodize, helping you choose the optimal finish for your metal projects.

What Is Anodizing?

Anodizing is essentially an electrolytic passivation process that thickens the natural layer of oxide on aluminum surfaces, helping metal parts resist wear and corrosion. Compared to naked aluminum, anodization improves the bond between adhesives, undercoats, and metal surfaces, much like chem film. This relatively thick, porous layer also absorbs dyes to create a unique decorative look, while its nonconductive nature helps insulate components against electricity. Anodized threaded components are also considerably less prone to galling.

Anodized coatings augment these properties of aluminum and other nonferrous metals: 

• Adhesive bonding
• Cleanability
• Decreased coefficient of friction
• Corrosion resistance
• Electrical insulation
• Paint adhesion
• Wear resistance

Impurities within limit corrosion resistance, so anodization is less effective for aluminum alloys, including materials like copper, iron, or silicon. Anodized metal surfaces also conduct heat less efficiently, expand more readily when heated, and have higher melting points.

Types of Anodization

There are many types of anodizing, though manufacturers mainly use three types. The anodization specification is Mil-A-8625, a standard for military and aerospace applications.

These are: 

• Type 1 anodizing: Using chromic acid, this method neither causes damage nor fatigue to aluminum, resisting stress while also offering good self-healing and corrosion resistance properties; however, manufacturers who use this anodization technique must deal with stricter environmental regulations, as chromic acid is both carcinogenic and noxious. Silvex does not offer this type of Anodize due to the environmental hazards associated with
• Type 2 anodizing: The most common type of anodizing, this approach uses sulfuric acid rather than chromic acid, producing porous surfaces that are easily dyed; this method for anodization is less expensive as it uses less energy and requires no special waste treatment, while the chemicals used are also more economical.
• Type 3 anodizing: Also referred to as hard anodizing, this method also utilizes sulfuric acid as an electrolyte solution, with higher current densities and voltages, along with lower temperatures, that produce highly porous yet considerably thicker metal surfaces, making it more durable due to the thicker coating, however, it doesn’t suit parts that require tight tolerances, though it does offer superior wear and abrasion resistance.

Used to prime surfaces for adhesives and paint, type 1 anodizing suits components that require tight tolerances, as it doesn’t notably alter dimensions; it’s commonly used for aircraft components. Type 2 anodizing is often used for decorative purposes since it readily absorbs adhesives, dyes, and paints; it’s used for architectural purposes, consumer electronics and goods, kitchenware for the military, optical components, and armed forces. The aerospace and defense industries extensively use type 3 anodized components, which are used for compressor fittings, gears, hinges, insulation plates, linear guides, pistons, valves, vehicle components, and other parts.

Having delved into the world of anodizing, we’ve uncovered how this versatile process improves corrosion resistance and adds aesthetic value and surface hardness to aluminum parts. From decorative finishes to protective layers, anodizing proves to be a powerful technique in various industries.

Join us for Part 3 of our series, where we will compare the real-world applications and industry uses of chem film and anodizing, helping you make an informed choice for your projects.

In the world of metal finishing, choosing the right surface treatment is crucial for ensuring the longevity and performance of your metal components. In this first part of our series, we will dive into the intricacies of chem film, exploring its properties, application process, and the benefits it offers. By understanding chem film, you can make informed decisions about its suitability for your specific needs and how it compares to other finishing methods.

What Is Chem Film?

Chemical film, commonly known as chem film, is a chemical process that facilitates the conversion of a metal’s surface into a protective layer through a series of chemical reactions. Unlike traditional plating methods that add a metal layer, chem film creates a protective coating by chemically interacting with the existing metal substrate. The main advantage of chem film finishes lies in their ability to inhibit further corrosion of metal surfaces, offering long-lasting protection.

Moreover, chem film treatments enhance the adhesion of organic coatings, making them an ideal pre-treatment step before applying paints or powder coatings. This improved cohesion ensures a more durable and uniform finish. In addition to corrosion resistance, chem film coatings play a crucial role in maintaining the electrical conductivity of metal surfaces, further enhancing their utility across various applications.

Types of Chem Film Coatings

Though there are various kinds of chem film coatings, they differ in the chemistry they use. The two methods most often used are type 1 and type 2 of the MIL-DTL-5541 standard, a military specification. Type 1 uses a chemical called hex chrome, known by its chemical name sodium dichromate, as it contains hexavalent chromium. Hex chrome is both hazardous to the environment and carcinogenic. Hence, the Environmental Protection Agency (EPA) and Occupational Safety and Health Administration (OSHA) require permits to use and dispose of the chemical.

Advantages of the MIL-DTL-5541 type 2 technique include:

• Faster processing times.
• Fewer steps in the process.
• Room temperature processing. 

The type 2 technique uses titanium, trivalent chromium, or zirconium to replace hex chromium. Additionally, the type 2 chem film coatings technology has advanced considerably, making it safer and quicker.

As we conclude our exploration of chem film, it’s clear that this finishing technique offers numerous benefits, particularly in enhancing corrosion resistance and providing an excellent base for subsequent coatings. Whether you’re working in aerospace, automotive, or electronics, chem film stands out as a reliable choice for protecting aluminum components. Stay tuned for Part 2 of our three-part series, where we will delve into the world of anodizing.

For manufacturers and fabricators alike, choosing a sulfuric anodize vs. hard anodized finish for their aluminum products directly relates to the product’s application requirements. Though hard and sulfuric anodize finishes are widely used electrochemical processes that provide a protective coating to aluminum and other metal products, each finish has properties tailored to specific applications that will affect the product’s performance and longevity. Continue Reading