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Different Methods Of Surface Finish In CNC Machining

by | May 9, 2024

Surface finishing is essential in the CNC machining process, not only to meet aesthetic standards but also to enhance functionality, ensure dimensional accuracy, improve durability, and meet specific application requirements. It is a critical step in the manufacturing process that directly impacts the performance and quality of machined components and end products.

This detailed blog will look into the techniques of CNC machining surface finishes, including information on procedures, comparisons, and the selection of appropriate finishes for particular applications.

Key Takeaways

  • Surface finishing is the last step that removes imperfections, improves aesthetics, and protects surfaces from corrosion and wear resistance.
  • While surface roughness describes smoothness, surface finish encompasses the entire process of creating strong and smooth surfaces.
  • Finishing techniques can add material and remove material to alter the surface.
  • CNC surface finishes consider three aspects: lay (direction of machining marks), roughness (microscopic peaks and valleys), and waviness (larger, irregular deviations).

What Is Surface Finish?

Surface finish is a step-by-step process of coating and texturing the surface of a part after its machining. This manufacturing process is specially used to remove visible tool marks, thereby improving the appearance, mechanical properties, and characteristics of a product.

By adjusting the surface finish, manufacturers can increase corrosion resistance, reduce friction, improve sealing capabilities, and guarantee the part fulfills the required criteria for its intended application.

The contract manufacturing company in Chennai is adept at providing excellent surface finish services.

Various Surface Finish Methods

There are various surface finish methods existing to improve the surface imperfections, texture, and appearance of the product. Let us look into the important surface-finish methods.

1. Electroplating

This is one of the most used CNC machining surface finishes because of its advantages and adaptability. The electroplating finish creates a thin metallic coating on the workpiece, protecting the interior component from impurities and corrosion.

In addition to its practical advantages, electroplating is widely valued for its capacity to improve the visual appeal of surfaces. With ornamental and satin finishes available, electroplating is one of the most appealing finishing alternatives in the market. This makes it an excellent choice for situations where aesthetics are a top priority. Electroplating is a wonderful alternative for increasing the visual appeal of a product or improving the appearance of a component.

2. Powder coating

Powder coating is a dry finishing procedure that involves electrostatically applying a powder material to a surface and then curing it with heat to produce a hard, protective covering.

This method is notable for its ability to generate a thick, homogeneous coating with no lines or sags, resulting in outstanding durability and resistance to chipping, scratching, and corrosion. The variety of possible hues and treatments, from matte finish to high gloss, provides great visual adaptability.

Powder coating is mostly used on metal surfaces such as steel, aluminum parts, and brass, making it an attractive option for automobile components, outdoor furniture, and industrial equipment. Its sturdy nature means that components can resist severe conditions and heavy use.

3. Passivation process

Passivation is a popular post-processing method used in CNC machining to improve product surface quality and performance. Following the machining process, the part’s surface may include micro-roughness or surface contaminants, which can have a detrimental influence on the part’s performance over time. Passivation can assist in alleviating these concerns.

It is a chemical process where the component is often immersed in a passivating acid bath, such as nitric or citric acid, to remove surface impurities and promote the creation of the protective oxide layer.

Passivation is required for medical devices, food processing equipment, and any stainless steel components exposed to corrosive conditions. It increases the parts’ lifetime and dependability by providing a corrosion-resistant finish.

Various Surface Finish Methods

4. Grinding

Grinding is a finishing procedure that employs an abrasive wheel to remove sharp edges and produce smooth surfaces or accurate geometrical forms on a product.

It produces great accuracy and surface quality, with finishes as smooth as 0.1 μm Ra (average surface roughness). It is the preferred approach for items that require precise tolerances that CNC milling machines cannot provide.

Grinding is widely employed in the tool manufacturing, automotive, and aerospace sectors, where accuracy and surface integrity are critical. It is particularly effective for hard materials such as hardened steel, ceramics, and carbides.

The Precision Machined Components Manufacturers in Chennai are quality-driven and ready to customize parts. Whether you need strict dimensional tolerances and smooth finishes or you need more corrosion and wear resistance, our CNC machining finishes might fulfill your needs.

5. Bead Blasting

Bead blasting is a finishing procedure that involves blasting items with tiny glass beads using a pressurized air gun. This procedure primarily enhances aesthetics, producing a matte or satin surface with a light texture. It is a primary finish that mechanically modifies the surface or erases machining markings by eliminating extra material, leaving a smooth surface.

Bead blasting has the advantage of producing a uniformly textured finish. However, it has little influence on tolerances but can change the surface’s critical dimensions. It is also a manual process with variables such as air pressure and glass bead size; thus, the results are not always consistent.

When bead blasting plastic components, ensure that they can survive the impact. If not, try injection molding as an alternate method for achieving a matte appearance.

6. Electropolishing

Electropolishing is an electrochemical procedure that smoothens and streamlines the tiny surface of a metal component.

Electropolishing minimizes surface roughness by dissolving the material’s outer layer, yielding a brighter, smoother finish. These surface treatments can also enhance the part’s corrosion resistance and cleanliness.

This method is mostly used on stainless steel, although it may also be applied to aluminum, copper, and other metals. It is widely used in the medical, food and beverage, and pharmaceutical sectors, where hygiene and cleanliness are essential.

Electropolishing has two advantages: it improves visual appeal while also increasing abrasion resistance. However, it may be expensive, and like other electrochemical processes, it needs rigorous waste management and environmental safeguards.

Custom cable manufacturers in India heavily adopt surface finish treatments to ensure smooth, durable, and high performance of their products.


CNC machining surface finishes are essential for removing visible tool marks, improving aesthetics, and maintaining functioning. With minimal room for error in this last production process, rely on our specialists’ skills and tools to provide remarkable outcomes.

We provide a number of finishing options adapted to your unique requirements. Our team’s significant experience in a variety of production fields ensures high-quality products with an impressive appearance. Partner with us for a hassle-free experience and a dedication to excellence in all aspects of your CNC machining requirements.

Frequently Asked Questions(FAQs)

Can you blend different surface finishes?

Yes, you can incorporate several CNC finishes to take advantage of their unique qualities. For example, bead blasting helps to achieve a precise matte texture before adding another finish.

What factors should be considered when choosing a surface finish method for CNC machined parts?

Factors to consider while choosing a surface finish method include:

  • Material properties (e.g., metal, plastic).
  • Desired surface properties (e.g., smoothness, hardness).
  • Functional requirements (e.g., corrosion resistance, electrical conductivity).
  • Aesthetic preferences (e.g., color, texture).
  • Cost and production time constraints.

How does surface finish impact the overall quality of CNC machined parts?

Surface finishing impacts the overall quality of CNC machined parts by ensuring they meet design specifications, functional requirements, and visual standards. Proper surface finishing enhances part performance, durability, and user satisfaction.

What are some considerations for post-CNC machining surface finishing?

Considerations for post-CNC machining surface finishing include:

  • Compatibility of finishing method with machined material.
  • Handling of delicate or complex geometries.
  • Quality control and inspection processes.
  • Environmental and safety regulations (e.g., disposal of chemicals).
Amulya Sukrutha

Amulya Sukrutha

About the Author

Amulya Sukrutha, passionate computer science engineer specialized in Data science field. I also describe myself as a enthusiastic strength and endurance trainee. I have played professional Tennis during my early years and found my path in Software development and machine learning later. I’m also passionate about creating content, and learning about new technologies.