How to Choose the Right Surface Finish for CNC Aluminum Parts?

CNC Aluminum Parts

cnc parts

CNC machining is one of the most booming industries in recent times. CNC or computer numerical controlled machines have enabled many businesses to reach a high level of precision and quality at lower cost and lead times. We have seen industries like automobile and aerospace bring revolution with the CNC machining technologies.

CNC machines can manufacture parts on various materials, but aluminum is the most used. The reason behind it is the versatile nature of the material that enables the production of precision parts. This article will be your guide to choosing the right surface finish for CNC aluminum parts.

Why Need To Make Surface Finish For Aluminum?

Aluminum CNC machining is used mainly in the aerospace industry and is known as the standard grade material for precision CNC machining. It shows high machinability and strength-to-weight ratio. This property makes it the ideal workpiece for many manufacturing processes.

Improving the surface finish can help to improve the quality and life span of the machined aluminum components and resist the corrosion between mating parts.

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Surface finishes ensure that the machined parts are ready for their desired application. There are several reasons why aluminum surfaces must have a precise finish. It includes color, hardness, reflectivity, and electrical conductivity.

Here are the main reasons we make the surface finish for aluminum machine parts.

To improve corrosion resistance

The main reason for finishing the surface of the metal is to improve the wear and corrosion resistance. It also ensures that the metal part lasts longer

To enhance appearance

Another reason for the surface finish is to enhance the overall appearance of the metal part. We do that by adding colors, improving the texture, and keeping the appearance aesthetically pleasing.

To prepare the metal

The surface finish helps prepare the aluminum part for the desired application. Some surface finishes prepare the surface for another finish, like mechanical finish before anodizing or powder coating helps achieve a smoother and better finish.

6061 and 7075 difference

Choosing an aluminum alloy depends upon the characteristics required for the application of the part. In Aluminum CNC machining, two types of alloys are the most common.

    • Aluminum 6061
    • Aluminum 7075

Aluminum 6061 contains magnesium and silicon as the primary alloys. While Aluminum 7075 has zinc and copper as the alloying materials. There are various aluminum 6061 in the automotive and shipbuilding industries than 7075. It is widely used in vehicle bodies, marine fittings, and yachts. Meanwhile, Aluminum 7075, having more strength, is used for high-strength manufacturing like aircraft, spacecraft, military, and defense applications.

We can study the difference between aluminum alloys based on these three characteristics.


CNC machining uses different cutting tools like drills, lathes, mills, and routers to produce the part of your desired shape and size. So, the material's machinability plays a vital role in aluminum CNC machining.

Complex shapes require higher machinability, which 6061 alloys can achieve. The 7075 alloy is a harder material that can not be reformed very easily.


The strength of aluminum 7075 is far more than that of 6061. The zinc and copper alloy is tensile, hard, and more difficult to weld than other aluminum alloys.

Surface Finish:

Different types of finishes can sit on the surface of aluminum alloys. Aluminum 6061 and 7075 can easily form a layer of oxides on the surface when in contact with air or water.

Surface Finish For Machined Aluminum Parts.

Aluminum parts can undergo a wide range of surface finishes. The main reason to finish a surface is to improve the corrosion resistance and the overall appearance of the custom aluminum part. We have discussed some of the most used finishing techniques for machined aluminum parts which will help you choose the right finish for your machined part.

Anodized Finish:

Anodizing is the most used surface finish technique to improve the corrosion resistance of the metal parts. It is an electrochemical process that uses metal alloys to thicken the surface with an anodic oxide layer and make it more durable and resistant to wear.

Powder Coating Finish:

Powder coating is mainly used for parts that require colored surfaces. It can coat a thick layer of up to 75 μm. Powder coating is best for outdoor applications as it makes them more corrosion, UV, and abrasions resistant.

Liquid Paint:

A liquid paint surface finish is used to get a thin layer of coating on the surface of the metal. Because it contains volatile compounds, most of which are evaporated during the process. The remaining volume solids form a protective layer on the surface.

Mechanical Finish:

Mechanical finishes are usually best to prepare the surface for other finishes. It includes grinding, polishing, tumbling, and buffing. After this, the part proceeds to further the finishing process and helps to reach the high precision required finish.


Aluminum is one of the widely used corrosion resistant machining materials in CNC machining because of its high strength-to-weight ratio and has non-corrosive properties. CNC machined aluminum parts work best in the aerospace manufacturing industry. It is a versatile material, is easy to use, and can undergo many heat treatments

Worthy Hardware is the leading CNC aluminum parts manufacturing company. With hundreds of ongoing projects worldwide, we are proud to say that we are the best in this business! Give us a call (0086-13143254839 )or fill out this form so our representatives can get in touch with you.


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