xiehe model

How does the CNC machined surface texture look?

CNC machining surface texture is very important to our products. Since the surface technology of many manufacturing companies has been applied in the product development process. As a customer, you need to define your requirements for surface texture and production technology. You are willing to assist to achieve your goals. In this blog we will discuss some of the most common production techniques that lead to the production of products with specific surface textures. The surface texture of CNC machining will vary depending on the production technology used.

The following are different CNC machining processes and finishing standards

Common RA levels and values

CNC machined surface texture

A surface texture described by various levels of smoothness or roughness of the surface. RA values are used to show different levels of surface texture. The RA scale consists of multiple values calculated in the form of microscopic peaks and valleys quantified by the average of surface roughness.

Different machining and finishing methods are suitable for different RA values. Understanding the manufacturing process that produces a specific RA value is critical when working with various designs. The RA value of 1.6 is suitable for manufacturing processes such as sawing, shaping, drilling, and EDM.

Boring and turning are manufacturing processes that yield an RA value of 0.4. An RA value of 0.8 is suitable for a wide range of operations including; milling, broaching, reaming, laser, die casting, etc. A customer who knows these RA values will help the manufacturer to customize his requirements to meet his surface texture needs.

The production process includes

CNC milling

A subtractive process is involved, so CNC milling involves the rotation of a tool on its spindle and the reduction of material to obtain the final product shape (including metal or plastic materials).

When the milling action occurs, the tool rotates rapidly, leaving behind some small scratches, whose pattern corresponds to the rotation of the tool. Engineers can creatively improve scratch patterns and come up with unique textural effects by using different cutting tools or varying cutting speed and depth. If the best results are desired, the CNC machines used should be highly accurate and rigid. Most CNC milled surfaces have a Ra of 0.8-1.6.

CNC turning

When the workpiece is mounted on the chuck, the tool is stationary and the workpiece rotates continuously. CNC turning creates a regular pattern on the workpiece. CNC turning is also an excellent method for engineers and designers to develop circular features such as threaded holes, grooves and stepped diameters.

The difference between CNC turning and CNC milling is that in CNC turning the tool rotates relative to a stationary workpiece, whereas the tool is stable relative to a rotating workpiece mounted on a chuck. With the correct cutting tool, a surface Ra of 0.4 is possible. The surface texture of CNC turning is very different from that of CNC milling because its scratches are closely spaced and therefore appear smoother.

CNC grinding

The CNC grinding process involves the movement of a grinding wheel against a rigid workpiece. The grinding wheel removes the pattern from the surface, making it even. The best grinding should have Ra0.05 or mirror surface texture with excellent cutting speed and grinding lubricant. CNC grinding is ideal for flat surfaces and produces the smoothest surface textures.

Chemical lithography

Chemical lithography is a subtractive manufacturing process that uses high temperatures in a controlled environment to selectively remove material to produce top-quality precision metal parts in a variety of shapes. Chemical photolithography can be used to design specific patterns.

EDM/Wire Cutting

Electrical discharge machining or EDM is a machining technique that uses a special wire to cut conductive metallic materials. The cable is easy to cut even in corners because it is cut without contact.

In addition, other types of surface texturing include: sandblasting, hand sanding and water spraying.