What’s the difference between 3, 4 & 5 Axis CNC Milling?

07 November 2023
3, 4 & 5 axis milling

Recent years have witnessed significant advancements in parts manufacturing techniques, driven by the ever-evolving demands of diverse production sectors. Among these techniques, machining stands out as a fundamental method, involving the precise removal of material to fashion high-accuracy components.

Now, let’s delve into the distinctions between 3, 4, and 5-axis CNC milling. Discovering the right choice for your CNC machining projects—whether it’s a 3-axis, 4-axis, or 5-axis CNC machine—is a crucial decision.

What’s the difference?

The key distinction among 3, 4, and 5 axis milling machines lies in their motion capabilities. In 3-axis milling machines, the cutting tool direction remains fixed throughout the entire cutting path, whereas in 4 and 5-axis machines, the workpiece can also undergo movement.

For instance, in 4-axis machining, an additional rotational axis supplements the initial three, typically providing a 360° rotation in the horizontal plane.

In summary:

  • 3 axis has X, Y, and Z axes
  • 4 axis has X, Y, Z, and A axes
  • 5 axis has X, Y, Z, B, and C axes

In short, the more complex the workpiece and cutting tool movement, the more complex the final machined product can be. This complexity often requires a higher financial investment.

CNC machinining
Image Clayton Cardinalli

3 Axis Machining

3-axis CNC milling remains one of the most popular and widely used machining processes but also the most simple. The workpiece is fixed in position and the spindle can move along the X, Y, and Z  axes in linear directions.

This represents a fairly straightforward form of CNC machining, ideal for producing products with uncomplicated designs. It’s particularly well-suited for parts with shallow features, but its effectiveness diminishes when dealing with deeper components featuring narrow cavities.

In such cases, the process can become labor-intensive, resulting in less-than-ideal finishes. Consequently, 3-axis machining finds its strength in crafting planar milled profiles, precise drillings, and threaded holes aligned with a single axis.

4 Axis Machining

The introduction of a 4th axis, known as the A-axis, adds rotation around the X-axis. While 3-axis machining relies on the linear axes (X-Y-Z), the 4th axis involves the rotation of the workpiece. Typically, 4-axis machines are of the ‘vertical machining‘ type, where the spindle revolves around the Z-axis.

In this setup, the workpiece is positioned along the X-axis and can rotate with the fixture on the A-axis. 4-axis machining presents a more cost-effective approach to machining parts that are theoretically feasible on a 3-axis machine. This not only accelerates the machining process but also enhances precision in machining operations.

sven daniel eaanLTG7TCU unsplash
Image: Sven Daniel

5 Axis Machining

These CNC milling machines can employ two of the three possible rotation axes, depending on the machine type. Some machines utilize A-axis and C-axis rotations, while others leverage B-axis and C-axis rotations. These rotations can be achieved either by the workpiece itself or by the spindle.

Five-axis milling machines can process different sides of the workpiece without changing the position of the workpiece on the worktable, which can greatly improve the processing efficiency of prismatic parts. Thanks to the great versatility of these machines, they are often used for the following applications: medical parts, aerospace parts, titanium parts, oil and gas mechanical parts, military products, etc.

You should keep in mind that although there are many advantages in using 5-axis machinery compared with 4-axis and 3-axis, not all products are suitable for 5-axis CNC machining, and those suitable for 3-axis CNC machining are not necessarily suitable for 5-axis machining.


We work with hundreds of machine shops to enhance and accelerate their quoting process. Take control of your quoting procedure and streamline your pre-production workflow: our real-time inventory management empowers you to efficiently oversee your resources, leading to a smoother and more productive operation.

Whether you’re an SME machine shop or a multinational OEM, AMFG offers a comprehensive end-to-end MRP system to enhance your inquiries, quoting, and pre-production processes.

Find out how AMFG can supercharge your Additive Manufacturing and CNC Machining processes today.




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