Aluminum alloys are among the most widely used metals on the global market. It’s not
just limited to simple ore deposits and it has a very high relevance in our daily lives.
These materials are very light in weight, very strong, and very resistant. They
are corrosion-resistant because of a thin oxide layer that cannot be formed at
temperatures below 100 Degree Celsius. Nonetheless, different types of aluminum
coatings are used frequently, where painting, anodizing, and powder coating are the
most common.

Why Coat Aluminum?

Aluminum Coated Parts

A valid inquiry arises: Why add a coating to aluminum if it already has a
natural safeguard?

Current producers and users demand better performance from aluminum parts than in
the past. Sometimes these parts are required to operate in conditions that are beyond
the capability of the oxide layer to protect the material.

For instance, if it was used to cover aerospace components, the aluminum cover would
be exposed to a high temperature near the melting point of the oxide layer. This
protective film can easily crack if the temperatures rise or fall very quickly. In marine
applications, aluminum parts are subjected to a highly corrosive marine environment,
which slowly causes the material to corrode. Due to these challenges, manufacturers
have resorted to using aluminum coatings.

Top 09 Aluminum Coatings For Your Products

Selecting the right surface finish can make all the difference between just having
products labeled as ‘good’ and having outstanding products. Surface finishes also
improve corrosion protection, wear protection, and the appearance of aluminum
extrusions so that aluminum extrusions not only have longer service life but also have
a better appearance.

Take a look at the different available custom aluminum extrusion finishes and the
advantages that each has to offer. Most of these finishing processes may also be used
on die-cast, roll, or machine aluminum parts.

● Mill Finish
● Anodizing
● Powder Coating
● PVDF Coating
● Other Liquid Paints
● Mechanical Finishing
● Wood Grain Aluminum
● Alodining
● Bright Dipping

1. Mill Finish

  Aluminum Mill Finish  

 

Mill finish aluminum extrusions refer to aluminum products that have left the extrusion
die in their original form. This finish may have visible die and tooling marks, oxidation,
and a flat, and whitish ‘rust’.

Ordinarily, a mill finish is fine for applications where price is the major consideration,
and appearance is inconsequential. In the case of items that should last longer and
retain a rather more professional touch, it may be wise to consider other aluminum
finishing techniques.

2. Anodizing

                                        Anodized Aluminum Parts

Anodizing is widely used for increasing the corrosion protection and the wear
protection of aluminum parts. It also includes other characteristics that include
enhanced heat transfer rate, and ability to accommodate dyes.

Anodizing does not add a coat to the surface of the aluminum in the manner of other
paints and coatings and such. However, this forms an electrochemical process that
enhances the thickness of the natural aluminum oxide layer which offers excellent
protection. While anodizing can take up dyes, the variety is limited compared to that of
the powder coatings.

3. Powder Coating

                          Aluminum Powder Coating

When it comes to durability, UV stability, and rich, intense colors – the best material
that many designers love to work with is called powder coating. Here, parts made of
aluminum are washed and prepared for a dry paint powder applied through the use of
an electrostatic gun. Subsequently, the parts are baked to melt and cure the coating
and in the process, the coating is made to achieve a uniform surface.

Although powder coatings are not as hard or abrasion resistant as anodized surfaces
they do possess excellent appearance and good corrosion protection if the coating is
not damaged. Moreover, powder coats are slightly better for the environment than
liquid paints as they contain solvents with volatile organic compounds (VOCs).

4. PVDF Coating

                                        PVDF Aluminum Coating

PVDF coatings are resin-based finishes comprising color pigments that are
incorporated into the coatings. Such coatings have to be applied in a factory, and they
enable a range of matte-finish colors across the visible spectrum.

PVDF coatings are relatively resistant to corrosion, fading, and chemicals, thus suitable
for external uses such as aluminum wall cladding. While powder coatings, PVDF does
not require an oven to cure and it can be applied in a much thinner layer than powder
coatings. When compared to powder coating, PVDF coatings may be seen as a little
more extravagant, but they are free of hazardous VOCs.

5. Other Liquid Paints

Even though PVDF is classified as a liquid paint it is different from other liquid painting
techniques. The liquid paints are ideal for a situation where particular colors are
needed, especially for short-batch production. This is because we find that there is a
wide range of color choices and the freedom to blend paints in specific amounts
required for certain jobs.

However, it is important to mention that liquid paints solvents in most cases are
composed of hazardous VOCs that are dangerous to health and the environment. For
these finishes, painters have no option but to use VOC abatement systems to tackle
the risks involved.

6. Mechanical Finishing

Mechanical finishing thus refers to a range of treatments that are directed at altering
the surface of aluminum parts. Some of the methods include abrasive blasting,
grinding as well as polishing.

Unlike chemical finishes which use chemical solutions on surfaces, mechanical finishes
use abrasive material to polish aluminum. This approach can enhance looks and ready
the surface for further surface treatment operations.

7. Wood Grain Aluminum

Sublimation is a technique used in art to give aluminum a colored finish. This technique
allows more design flexibility because the designs are transferred from a film-wrapping
onto the aluminum surface through heat.

Wood grain patterns are especially popular in extruded aluminum uses since they
enable designers to design products such as outdoor furniture or window frames that
appear like wooden products but with the advantages of aluminum materials.

8. Alodining

Aluminum Alodine

Alodining is cheaper than anodizing. This method refines the passivating oxide layer
present on aluminum surfaces and hence improves corrosion protection. Alodine
coatings are not as strong or hard-wearing as anodized finishes but they are
electrically conductive, which could be important in some cases.

However, it should be noted that the use of Alodine solutions is not as eco-friendly as
some of the products presented above.

9. Bright Dipping

                                  Bright Dip Aluminum Parts

Bright dipping is a process of finishing that gives aluminum parts a reflective surface.
This technique requires that the aluminum be placed in an acidic bath where the tiny
ripples on the surface of the material are polished to a mirror-like surface.

 

While this process may be essential for some applications, it has environmental
implications and safety issues. Also, bright dipping can only be done with certain
aluminum grades, such as the 6463 aluminum grade.

Comparing Anodizing vs. Powder Coating

Comparing anodizing and powder coating is not entirely fair because the two
processes are different. These two processes can work hand in hand. Anodizing makes
the aluminum surface porous and hence is not shiny like the normal metallic surface
but has a rather like powder form. These pores ensure that they trap powder particles
during the process of melting the same.

 

Anodized aluminum and powder coatings are available in a large number of colors.

 

Both of them offer a protective shield against the corrosion and wear of equipment.
However, anodizing yields a far superior degree of protection because the layer formed
is part of the aluminum.

 

Anodizing vs. Liquid Painting: What’s The Difference

When comparing painting to anodizing, the pores formed during anodizing are less
desirable for achieving a high level of surface finish than powder coatings. Anodized
aluminum generally has a lower surface gloss compared to painted samples. But for a
matte texture anodizing is the best.

 

Although anodizing is non-toxic it requires a large amount of energy and equipment
while painting is relatively cheaper.

 

Many paints have high electrical conductivity; nonetheless, anodized coatings’ porosity
decreases the conductivity of the aluminum part. This factor should be taken into
account while using aluminum parts in electrical installations.

 

Selecting the Right Finish for Your Project

It’s crucial to know which of the aluminum finish types is protective because aluminum
can be shiny, mirror-like, rough, or have patterns on the surface. Choosing the right
finish plays a critical role in improving your products, and ensuring that the aluminum
part is of the right quality for its intended use.

 

The moldability and ability to shape make it ideal to be used in many sectors
such as automotive, aerospace, marine, defense, and consumer goods sectors.
However, the environment should be taken into consideration if you are choosing
aluminum coatings for your project especially when the intended products are to be
used outside.

 

Environmental conditions like humidity, temperature, exposure to sunlight, and UV
rays are known to affect the durability and efficiency of aluminum parts. As a result,
when selecting a finish for the aluminum machined parts that will be used outdoors, it
is recommended to go for a finish that will offer the part a long life by being able to
withstand harsh weather conditions.

 

However, cost control is also an important factor when selecting the aluminum coating.
However, quality should not be an issue of concern while your budget determines
everything that you are going to do. Selecting a high-quality finish may add to the
machining price, and therefore, the client should research to identify a finish that fits
his or her quality and budget.

Elevate Your Projects with Professional Aluminum
Anodizing

Aluminum coating is crucial to your bespoke aluminum parts as it turns the
components from “standard” to “premium.” An expert in aluminum finishing is the
most important partner that one would need when it comes to manufacturing
aluminum parts. Knowledge of the different finishes will assist you in choosing the right
one for your products and their uses.

 

We provide high-quality aluminum finishing services at a reasonable price range
suitable for your company’s financial capacity at Shenzhen Feitai. Our experienced
product design, engineering, and quality control professionals work to make sure that
your aluminum parts get the right treatment for your applications. Get in touch with us
today to take your project to the right quality level that you want it to be. You can
upload your CAD file and get an instant quote from us right now!