Do you know what CNC machining means? The machining process involves shaping raw materials with various cutting tools. The precision and quality of CNC machined parts are exceptions. Yet, the CNC machined parts aren’t complete without the final touch – surface finishing. Processing the machined parts with suitable surface finish techniques improves the performance and the visual appeal.
Therefore, Machining Surface Finishe Services extends the product life, reduces friction, and protects against corrosion and wear. Let’s discuss the different surface finishes for CNC machining in brief:
Why CNC Parts Need Surface Finishing?
Even the most complex engineered components may only fall short of their potential with a proper surface finish. For instance, the surface finish can significantly reduce the wear and tear of a mechanical bearing. The surface roughness value that surface finishes can achieve on a CNC-machined surface is as low as 0.1 micrometers.
Surface finishes also serve to protect parts from environmental factors. For example, anodized coatings on aluminum parts can prevent oxidation and corrosion.
Furthermore, surface finishes are often combined with the CNC Machining Services. A polished surface finish provides a sleek, reflective appearance for the CNC parts.
1. Anodizing Finish
Anodizing is an electrochemical process that converts the metal surface into a durable, corrosion-resistant anodic oxide finish.
Through dyeing, anodizing adds a tough and protective coating to aluminum parts with vibrant colors. However, not all materials are amenable to anodizing. Metals like copper and steel are incompatible with the anodizing finish because they lack a suitable natural oxide layer. Thus, anodizing is ideal for aluminum and its alloys.
| Anodizing Aspect | Detail |
| What does it do? | Electrochemical enhancement of the natural oxide layer |
| Compatible Materials | Aluminum and its alloys |
| Result | Durable, corrosion-resistant finish |
| Thickness | 5 to 100 µm |
| Suitable Scenarios | Aerospace, automotive, outdoor equipment |
| Not Suitable For | Non-aluminum metals like copper and steel |
2. The Nitriding Method
Nitriding is a heat-treating finish that diffuses nitrogen into the surface of a metal to create a hard layer. It’s particularly effective for alloy steel, where the heat treatment improves hardness, wear resistance, and fatigue life.
The process is eco-friendly, as it uses less energy than traditional heat treatments. Nitrided surfaces exhibit exceptional resistance to corrosion, making them ideal for parts exposed to harsh environments. Furthermore, nitriding can target specific areas, offering flexibility in application.
- It enhances wear resistance and fatigue life.
- Nitriding improves surface hardness with minimal dimensional change.
- Eco-friendly, with lower energy consumption.
- This finish Offers exceptional corrosion resistance.
- Allows selective treatment of parts.
- Suitable for various alloy steels.
3. Chromate Conversion Coating (CCC)
CCC is a chemical treatment for metal surfaces (mainly aluminum) that enhances corrosion resistance. The chromate coating forms a protective layer without altering the part’s dimensions. It’s ideal for electrical conductivity without significant material buildup.
| Aspect | Detail |
| Application Method | Chemical bath immersion |
| Post-Treatment | Paint adhesion, preparation for further coating. It provides an excellent base for subsequent layers. |
| Surface Appearance | Clear to iridescent, yellow to brownish, depending on coating weight |
| Resulting Properties | Corrosion resistance, electrical conductivity, dimensional consistency, and tight tolerances. |
| Typical Industrial Use | Aerospace, electronics, military hardware, and kitchenware |
| Compatible Materials | Aluminum alloys |
| Environmental Impact | Contains hexavalent chromium, but regulated under REACH, RoHS |
4. The Powder Coating Finish
The powder-coating surface finish applies a protective layer to the part’s surface to enhance its durability and appearance. It is also known as the “dry finish approach” as it uses electrostatically charged powder. Then, it is subjected to curing under heat to form a thin skin.
The advantages of powder coating are
- It provides superior corrosion resistance to metallic and non-metallic parts.
- Different colors can be applied with powder coating.
- It increases the durability and performance of machined or fabricated parts.
- The powder coating is more environmentally friendly as it rarely emits volatile organic compounds (VOCs).
Summing Up
CNC machining precisely shapes materials. Meanwhile, surface finishes complete the process. The surface treatments on CNC-machined components boost visual appeal and functionality. Furthermore, techniques like anodizing, powder coating, nitriding, and plating protect the products from environmental and operational conditions.