What is the difference between 3-axis, 4-axis and 5-axis CNC?

2025-10-30

Numerical control machining is the manufacturing and processing of parts and products under computer control.

CNC machining involves the use of computer numerical control (CNC) machines to shape and size a piece of material (i.e., a workpiece) by automatically removing material. Typically, the material used is plastic or metal, and once the removal is complete, a finished product or product is produced.

This process is also known as subtractive manufacturing. To perform CNC machining, a computer application is used to control the movement of the machine tool. CNC machining processes include the most common milling and turning, followed by grinding, EDM, etc. Among them, milling is the application of a rotating tool to the surface of the workpiece, moving along 3, 4 or 5 axes. Milling is basically cutting or trimming the workpiece, and it can quickly machine complex geometries and precision parts from metal or thermoplastics. Turning is the use of a lathe to manufacture parts containing cylindrical features. The workpiece rotates on the axis and comes into contact with the Precision Turning tool to form circular edges, radial and axial holes, slots and grooves.

Compared with traditional manual machining, CNC machining is much faster. As long as the computer code is correct and meets the design, the finished product will have high dimensional accuracy and small errors.

CNC manufacturing is ideal for rapid prototyping. It can also be used to manufacture end-use products and components, but is generally only cost-effective for short, low-volume production runs.

Multi-axis CNC machining

CNC milling involves removing material using a rotating tool. Either the workpiece remains stationary and the tool moves over it, or the workpiece enters the machine at a predetermined angle. The more axes of motion a machine has, the more complex and faster its forming process can be.

3-axis CNC machining

Three-axis CNC milling remains one of the most popular and widely used machining processes. In three-axis machining, the workpiece remains stationary while a rotating tool cuts along the x, y, and z axes. This is a relatively simple form of CNC machining suitable for manufacturing products with simple structures. However, it is not suitable for machining complex geometries or products with intricate components.

Since cutting is limited to three axes, machining speeds can also be slower than with four- or five-axis CNCs, as the workpiece may need to be manually repositioned to achieve the desired shape.

4-axis CNC machining

In four-axis CNC milling, a fourth axis is added to the motion of the cutting tool, allowing rotation around the x-axis. Now there are four axes - the x-axis, y-axis, z-axis, and the a-axis (rotation around the x-axis). Most four-axis CNC machines also allow the workpiece to be rotated, which is called the b-axis, allowing the machine to function as both a milling machine and a lathe.

If you need to drill a hole on the side of a part or on the curved surface of a cylinder, 4-axis CNC machining is the best choice. It greatly speeds up the machining process and has high machining accuracy.

5-axis CNC machining

Five-axis CNC milling has an additional axis of rotation compared to four-axis CNC. The fifth axis is rotation around the Y-axis, also known as the B-axis. The workpiece can also be rotated on some machines, which is sometimes called the B-axis or C-axis.

Due to its high versatility, five-axis CNC machining is used to manufacture complex precision parts, such as medical components for artificial limbs or bones, aerospace components, titanium components, oil and gas machinery components, and military products.