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Customers who turn to us often request CNC machining services when looking to manufacture complex shaped metal parts. While it is common to use this broad term and it is not necessary to mention the exact manufacturing method, CNC machining requires two different methods.

They are milling and turning. Both are CNC machining methods, but they are not the same. CNC stands for Computer Numerical Control, which means that CNC milling and CNC turning use a computer system to guide the cutting machinery. Good CAD-CAM software can easily convert 3D models into readable codes for CNC machines. This determines tool usage and movement, cutting paths, etc.

While our engineers can make decisions about the proper operation of a part, it can be interesting to see the difference.

What is the difference between CNC milling and turning?

The short answer is this - CNC milling uses rotating tools, while CNC turning uses rotating parts for cutting.

Therefore, the two use different techniques to create the parts. While milling machines make complex parts from blocks of metal by removing excess material, turning is often used for cylindrical parts such as shafts.

What is CNC milling?

Let's start with milling. The first is the more traditional three-axis CNC milling machine. The tool can move in 3 directions of X, Y and Z axes.

While this places some constraints on the part geometry, it is sufficient for most jobs that require milling. A wide range of milling tools can provide different cutting methods such as end milling, face milling, hollow milling, etc. Multi-axis milling allows for 4 or more axes, including rotation of the tool and table. This provides additional flexibility. 5-axis milling machines are the most common of these and are capable of making almost anything that can be made with milling.

The size of the initial block is usually larger than the general size of the final part. As a result, precision milling can be performed on each side. Tolerances are very tight, so a good surface finish is easy to achieve.

What is CNC turning?

As mentioned earlier, CNC lathes are mainly used to manufacture cylindrical parts. These can be shafts, custom hollow tubes, cones or anything else that requires turning services.

While 5-axis machining can also create cylindrical parts, turning is more efficient, and the hourly rates for these machines are lower. The chuck holds the raw material (usually a round bar) in place. The chuck rotates at high speed together with the spindle. Maximum speed or RPM depends on the machine.

The single-point cutting tool is mounted on the turret. The turret can move in and out of the workpiece as it rotates, allowing the tool to make contact with the metal for cutting.

This highly precise machining method enables tight tolerances. This is why restraints and fits are often used with hole-based systems, as it is easier to achieve the desired accuracy on the shaft.

In conclusion

Although the two are often grouped under the same term -

- but they are not the same. Still, they complement each other perfectly to produce high-precision parts.

For example, turning a shaft may require adding features using a CNC mill.

Since both are widely used in manufacturing, it is wise to distinguish between the two.