Types of Surface Finishing for CNC Parts

We not only provide custom CNC machining services, but also post-processing of parts, such as common surface finishes. There is always one that can meet your needs.

Why CNC Parts need Surface Finishing Services

Finishing manufacturing process is a crucial step in the manufacturing of CNC parts to meet the specific requirements of different applications, ensuring durability, functionality, and compatibility with other components.

Improved Appearance
Surface finishing can significantly enhance the visual appeal of CNC machined parts. This is particularly important for parts that are used in consumer-facing applications, where aesthetics can be as important as functionality.
Increased Corrosion Resistance
Many surface finishing techniques, such as anodizing for aluminum or passivation for stainless steel, increase the corrosion resistance of the material. This is crucial for parts that will be exposed to harsh environments or chemicals.
Enhanced Surface Strength
Some finishing processes can enhance the surface strength and wear resistance of the parts. For example, processes like hard anodizing or nitriding can create a surface that resists wear and tear better than untreated metal, extending the part’s operational life.
Improved Surface Smoothness
Surface finishing can also improve the smoothness of a part, reducing friction and wear. This is particularly important for components that interface or move against other parts, such as gears or bearings.
Controlled Surface Properties
Certain finishing techniques can modify surface properties in specific ways. For instance, surface grinding and polishing can achieve high precision and surface flatness, which are critical for high-performance applications.
Increased Electrical Conductivity
Finishing processes like electroplating can be used to coat parts with a layer of a different metal, which can be crucial for electrical conductivity or other specialized characteristics.
Enhanced Chemical Resistance
Some finishes can protect against chemical degradation, which is important for parts used in chemical processing or exposed to potentially damaging substances.
Reduced Product Contamination
Finishes that create smoother surfaces at a microscopic level can reduce the tendency of the parts to harbor bacteria or other contaminants. This is particularly important in the food processing and medical industries.

Common Surface Finishing Processes

Surface treatment is an important processing method for CNC machined parts, which aims to optimize its surface characteristics through different technical means to adapt to various use environments and performance requirements.

Anodizing

This electrochemical process creates an oxide layer on metal surfaces, typically aluminum, enhancing corrosion resistance and allowing for coloration through dyeing.

Powder Coating

This technique involves spraying a fine powder onto the part and then curing it under heat to form a tough layer. It increases durability and offers a wide range of color choices.

Electroplating

This involves depositing a metal or another substance onto the part using an electrical current, enhancing properties like corrosion resistance, hardness, and conductivity. Common coatings include nickel, chrome, and zinc.

Passivation

Specifically useful for stainless steel, this chemical process removes free iron from the surface, bolstering the naturally corrosion-resistant chromium oxide layer.

Bead Blasting

By blasting small glass beads at high pressure onto the surface, this method achieves a uniform matte finish that reduces light reflection and enhances texture.

Polishing

This process uses abrasives or polishing discs to remove surface irregularities, achieving a mirror-like smooth finish that significantly enhances appearance.

Brushing

This technique creates a unidirectional satin finish by using brushes or similar tools, which adds visual depth and can hide minor scratches.

Black Oxide

Used primarily for ferrous metals, this chemical conversion creates a black oxide layer that improves appearance and offers mild corrosion resistance.

Chemical Film/Chromate Conversion Coating

This treatment provides a corrosion-resistant layer on metals like aluminum, serving also as a primer for additional coatings.

Laser Engraving

While mainly used for marking, it can also alter surface texture and appearance for decorative purposes.

Examples of Surface Finishes

Not sure which surface finish is right for you? Contact us for a personalized consultation and expert advice tailored to your specific requirements.

5 Factors to Consider When Selecting Surface Finishing

By carefully evaluating these factors, you can make informed decisions about the most suitable surface finishing technique for their CNC machined parts, ensuring optimal performance, durability, and cost-effectiveness.

FactorDescription
Performance RequirementsEvaluate the necessary characteristics such as wear resistance, corrosion resistance, and conductivity. These depend on the function of the part.
Material of the PartChoose a finishing process compatible with the material of the part to ensure effectiveness and prevent damage. For example, anodizing is good for aluminum but unsuitable for most steels.
Aesthetic ConsiderationsConsider the desired visual outcome, including color, texture, and gloss, especially for consumer-facing parts. Different finishes can enhance the product’s appearance.
Environmental ExposureAssess the environmental conditions the part will be subjected to, such as chemicals, temperature extremes, or physical wear. Select a finish that can protect the part under these conditions.
Cost and Process EfficiencyFactor in the cost of different finishing processes and their impact on the manufacturing timeline. Balancing these with the quality and performance benefits is crucial for a cost-effective process.