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How to Choose the Right Surface Finish for Machined Aluminum?

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How to Choose the Right Surface Finish for Machined Aluminum

With the increase of CNC aluminum business, modern technology has more details for aluminum processing details. Over the last hundred years, aluminum has been prominent in mass production and metal fabrication. Thanks to its lightness and softness, it’s an easy material to shape during CNC machining.

Compared to other metals such as titanium and magnesium, machined aluminum takes preference in the manufacturing sector due to its physical properties and excellent machinability. During the material selection process, it’s critical to understand that aluminum alloys have different grades depending on the application.

Once you select the alloy, there are a variety of finishes that you can use to add functionality to the customized parts. First, let’s look at some tips on how to select the right surface finish for your machined aluminum.

Choice of Aluminium Grade

The first step in starting your CNC aluminum machined projects is selecting the correct metal alloy. Each grade has its own set of unique properties and characteristics according to your needs. While checking for the aluminum capabilities, you need to consider the strength, conductivity, corrosion resistance, or a collection of all these.

The two most common aluminum metals in the industry are 6061 and 7075 aluminum alloy. So, what’s the difference between the two?

6061 vs 7075

· 6061 Aluminum Alloy

Classified under the 6xxx class of aluminum due to the high silicon content, this alloy has excellent mechanical properties and is a perfect choice for welding. In addition, it forms shapes easily, making it a top selection of extrusion projects.

It has the edge over the 7075 alloys when it comes to aluminum fabrication. This is because it has a lower hardness and has the necessary tensile strength. These two properties are essential in making the CNC machining process much easier.

In the manufacturing process, aluminum 6061 is used for 5 axis CNC machining. However, during the customization of parts, it’s more likely to be adopted for parts that require more ductility.

· 7075 Aluminum Alloy

The main difference when comparing 6061 vs 7075 aluminum alloys is that the latter is part of the 7xxx series, with zinc as the primary alloying element. Unfortunately, this metal is not good for welding because it’s extremely prone to cracks.

Despite being one of the strongest types of aluminum, it’s easily degraded by corrosive effects. However, the high copper content makes it exceptionally strong. This impressive strength is an advantage when it comes to industry application.

The 7075 alloys can handle in high-stress environments in the aerospace industry, military, and high-wear parts. It’s also used for bicycle parts, fuselages, bicycle parts, and rock-climbing kits. During machining, it’s preferred for making molds and industrial tooling than 6061.

Aluminum Alloy

What is Aluminum Fabrication?

The alloy used in machining depends on the type of fabrication required. Cutting, bending, and assembling are the main types of aluminum fabrication. During the machining projects, aluminum is fabricated using different techniques depending on the manufacturer ad client needs. Its unique combination of properties makes it very suitable for fabrication.

Choosing the Right Surface Finish for Machined Aluminum

With CNC machining, metal parts and components need to go through post-processing to be visually appealing. Therefore, manufacturers involved in machined aluminum have to choose a surface finish that improves the final product’s appearance.

· Chemical Finish

When dealing with CNC machined aluminum, you can use a chemical mixture to make the surface extra shiny and spectacular. Treatments such as bright dripping give the machined aluminum a “mirror” finish. Machinists place the parts on a special dip solution to achieve a reflective surface and remove any stains.

· Mechanical Finish

Just like other metals, aluminum gets finished mechanically by either polishing, buffing, or blasting. These processes use abrasion to remove excess metal, add texture to the surface, and make it ready for other cosmetic finishes.

· Anodizing Finish

This process is mainly used in machined aluminum parts. It involves an electrochemical process that provides additional protection on top of the natural oxide film present on aluminum alloys such as 6061 and 7075. Aside from protection, this extra layer is excellent for insulation, decoration, and abrasion resistance.

· Powder Paint Coating

Powder coating is a common treatment for fabricated aluminum parts. The process involves using paint without a solvent. The mixture gets applied using a spray gun to provide a smooth coating on the metal. The matte or glossy coating gives a decorative finish similar to paint but has more durability.

· Liquid Paint Coating

Liquid Paint Coatings come in many colors. When used during extrusion, the paint forms a film with uniform thickness.

· Pre-Treatment

Aluminum surfaces can also get treated using a process known as pre-treatment. This method involves cleaning the metal with either an acidic or alkaline material. Once the pre-treatment coat is applied, you can add the powder paint on top to strengthen the resistance against corrosion.

Pre Treatment

Reasons for Machined Aluminum Surface Finishing

During aluminum fabrication, the metal comes with unique properties that make the process easier. So why do you need to have additional finishing on your aluminum parts? Let’s take a look.

· To Enhance Appearance

For most consumer products, appearance is critical. Finishing your machined aluminum part with powder or liquid paint coatings is well suitable for products that need a dash of color. Also, you can use other techniques to achieve a shiny look. Finishing is good for aesthetics.

· To Improve Corrosion Resistance

When comparing 6061 vs 7075 aluminum alloys, you have to check for corrosion resistance. Aluminum comes with its natural layer of an oxide film. However, in extreme conditions with moisture and temperature changes, you might need extra protection by anodizing.

· To Prepare the Metal

Mechanical and pre-treatment processes are essential in preparing the aluminum for other final finishes. CNC machined aluminum may need an extra coat or treatment to alter any hard surfaces.


Aluminum as a fabrication material is commonly used in CNC machining projects. This technology has aided in the production of CNC machining parts and components used in different industries and sectors. However, whether you are using 6061 or 7075 alloys in the manufacturing process, you have to select the right surface finish for your machined aluminum.

To get a quote for machined aluminum prototypes or custom parts, contact WayKen today.


Read also :, a professional manufactory of aluminum enclosures.

Kossi Adzo is the editor and author of He is software engineer. Innovation, Businesses and companies are his passion. He filled several patents in IT & Communication technologies. He manages the technical operations at

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