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Popular Surface Finishes for CNC Machined Parts

When it comes to producing machined parts, it’s important to consider the surface finish of the part. Different surface finishes can be achieved depending on the manufacturing process and materials used, so it’s important to be familiar with the various options. In this blog post, we’ll take a look at some of the most popular surface finishes for CNC machined parts, as well as the advantages and disadvantages of each. Read on to learn more about CNC machined parts and their surface finishes.


Anodizing is a popular surface finish for CNC machined parts. It provides a protective coating to the metal and adds an attractive finish. Anodizing is a process in which an electrical current is applied to the metal, creating a layer of oxide that prevents corrosion and increases wear resistance. The anodizing process also creates a strong bond between the metal and the anodic coating, providing additional protection against abrasion and wear. Additionally, it has the advantage of being non-toxic and relatively low-cost compared to other finishes.

Anodized parts have a sleek, uniform look and can be made to any color desired. However, the color of an anodized part will fade with time, so it is important to consider this when selecting a finish. Additionally, if not properly cared for, corrosion can occur due to environmental factors such as moisture or salt exposure. To protect against corrosion and maintain a consistent appearance over time, some manufacturers may opt for anodized type II. This type of anodization involves thicker layers of oxidation, making it more durable and less likely to corrode over time. The thicker layers of oxidation also provide increased wear resistance and better heat dissipation than standard anodizing processes. Anodized type II finishes typically appear more glossy than standard anodizing, giving off a bright sheen that helps draw attention to the finished product.

For those looking for something a little more subtle, matte anodizing is also available. With matte anodizing, the metal still undergoes the same electrochemical process as traditional anodizing but with fewer electrical currents and lower voltages. The result is a softer, more muted finish that still offers excellent corrosion protection and improved wear resistance. Depending on the application, matte anodizing may be the perfect choice for achieving a subtle yet elegant look. As always, it’s important to consider your specific needs before deciding on a finish. Although anodized type II offers great corrosion resistance and improved wearability, if your application requires added durability then opting for a higher grade of anodizing such as hardcoat may be the right choice.


Plating is a process by which an electrolyte solution is applied to the metal surface, resulting in a thin layer of metal being deposited on top. The most commonly used metals for plating are nickel, chromium, and zinc. Plating provides a protective layer on the part and can be used to add color or decorative elements. It is also often used to protect against corrosion or wear.

Plating is a relatively inexpensive process and can be used on any metal. It is particularly popular for aluminum parts due to its ability to reduce weight and enhance strength. Depending on the plating material chosen, it may also help improve electrical conductivity and resistance to wear and tear. The downside to plating is that it requires additional steps to prepare the surface before plating can occur, such as cleaning and sanding.

Plating is a great option if you are looking for a reliable and economical way to improve the appearance and performance of your CNC machined parts.

Powder Coating

Powder coating is an electrostatic process that uses a dry powder that is applied to the metal surface, then cured under heat. The powder forms a hard and durable finish that resists corrosion and oxidation, making it ideal for outdoor use. The process begins with pre-treating the part with either a sandblasting or chemical process. This pre-treatment helps the powder adhere to the surface of the metal and improves its durability. Once pre-treated, the part is ready to be powder coated. The powder is applied to the part using an electrostatic spray gun, which gives it a uniform coating. The part is then placed in an oven to cure the powder at temperatures of 250-400 degrees Fahrenheit.

The beauty of powder coating is that it can be applied in a wide variety of colors and textures, providing an attractive and unique finish to CNC machined parts. Additionally, it is one of the most economical processes available and offers excellent protection from corrosion and oxidation, making it great for outdoor use. Other popular finishing processes for CNC machined parts include chromate conversion coatings, and black oxide coatings. Chromate conversion coatings are primarily used as a primer before painting or other post-processing operations. Black oxide coatings are known for their rust-preventive properties and create an aesthetically pleasing black finish on steel or iron components.

Anodizing is a popular finishing process used on aluminum components and provides good abrasion resistance while also preventing corrosion. It creates a very thin layer of aluminum oxide on the component’s surface which provides superior wear and corrosion resistance compared to other surface treatments.

Brushed and Polished Surface Finish

Brushed and polished surface finishes are both popular options for CNC machined parts, as they are both aesthetically pleasing and functional. The most common way to achieve a brushed finish is with a sandblasting technique, which uses a pressurized stream of air and abrasive particles to abrade the surface of the material. This technique is typically used on metals such as aluminum, stainless steel, and titanium.

The end result of this process is a uniform brushed finish, which has a matte sheen that makes it visually appealing. This type of finish is ideal for parts that require extra protection from corrosion, or those that may come into contact with water.

Polished finishes are achieved by taking a surface that has been machined or ground and polishing it until it is smooth and glossy. This type of finish is perfect for parts that need to have an attractive appearance, such as those used in industrial or commercial settings. Common metals used for polishing are aluminum, stainless steel, brass, and nickel.

Both brushed and polished surface finishes are popular for CNC machined parts because they offer functionality, aesthetics, and protection from corrosion. Brushed finishes offer a matte sheen and protection from corrosion, while polished finishes provide a more elegant look with a glossy finish. No matter what type of finish you choose for your CNC machined parts, the result will be an attractive and durable product that looks great and functions effectively. One important factor to consider when selecting a surface finish is the grit size, which is a measure of how coarse or fine the abrasive media is. A coarser grit size will produce a rougher texture, while finer grits create smoother surfaces.

Finer grits are often better suited for more intricate parts since they can help reduce the risk of leaving marks or scratches. Grits can range from very coarse (20-60 grit) to very fine (2000-3000 grit). It’s important to use the correct grit size when selecting a surface finish so that you can get the desired results without causing any damage to your part.


CNC machined parts can be finished in a variety of ways to meet the needs of any project. Anodizing, plating, powder coating, and brushed and polished finishes are some of the most popular options available. Each of these finishes has their own unique benefits and drawbacks, so it’s important to understand what is right for your specific application. Ultimately, the surface finish you choose will depend on your design requirements and budget.

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