3-Axis and 5-Axis CNC Machining – How to Choose

You’re probably no stranger to CNC machining.

If you are, know that this is a subtractive manufacturing method that carves parts from solid blocks of material using Computer Numerical Control (CNC). In CNC machining, the term ‘axis’ refers to the number of directions the cutting tool or workpiece can move.

Why does this matter? Understanding the capabilities of 3-axis and 5-axis CNC machining is essential for making informed decisions during the design and manufacturing processes.

Axes in CNC Machining

In CNC machining, an axis refers to the motion range of the cutting tool or the workpiece. The movement can be linear (X, Y, Z axes) or rotational (A, B, C). The two most commonly used configurations are 3-axis and 5-axis CNC machining.

3-Axis CNC Machining Explained

In 3-axis CNC milling, the workpiece remains stationary while the cutting tool moves along the three axes (X, Y, and Z).

This type is often used for parts with less complexity and where the underside of the workpiece doesn’t need machining, or it can be set up again in the machine. Examples include simple milling tasks, drilling, and all designs that can be easily partitioned into a series of 2.5D cross-sections.

3-axis CNC machining is a staple in manufacturing due to its straightforward operation and lower machine cost. It’s ideal for simpler parts and high-volume production where cost-effectiveness is paramount.

However, the static workpiece limits its capability to handle complex geometries and undercuts without repositioning. It may require additional setup time for complex parts, increasing production time and costs. 

5-Axis CNC Machining Explained

5-axis CNC machining introduces two additional rotational axes, A and B, providing the cutting tool with a more comprehensive reach of the workpiece.

It’s the method of choice for complex parts like turbines or impellers, with intricate details and undercuts that would be challenging or impossible to achieve with 3-axis machining.

5-axis CNC machining produces high-quality intricate parts in a single setup, reducing production time and errors. It offers a better surface finish because it maintains the optimal cutting angle.

Despite these advantages, 5-axis machines are more expensive and require advanced programming skills, potentially limiting their use to high-value parts or those with complex geometries. Additionally, setting up the workpiece can be more complicated due to the additional degrees of freedom.

Design Considerations for 3-Axis vs. 5-Axis CNC Machining

Several factors can influence the decision between 3-axis and 5-axis CNC machining.

Part complexity is a crucial consideration. If your part requires machining from multiple angles or has intricate geometries, 5-axis machining may be necessary. If your part design includes undercuts, complex geometries, or complicated details, then 5-axis CNC machining could be the way to go. It can handle these challenging features more efficiently, saving you time in production.

Tolerances and finish requirements can also sway the decision—5-axis machining often delivers superior surface finish due to consistent tool orientation. However, for simpler designs and high-volume production runs, 3-axis machining can be more cost-effective due to lower machine and operation costs.

The production speed is another critical factor. If speed is of the essence, you might lean towards 3-axis machining for simpler parts due to its faster setup times. However, if the part is more complex, 5-axis machining can complete the job in a single setup, potentially reducing overall production time.

Production volume should also be considered. If you’re looking at high-volume production, 3-axis machines can offer efficiency and speed, making them a cost-effective option. However, for lower-volume production or prototypes with complex geometries, 5-axis machines are usually more economical.

Find the Best Fit for Your Project

Choosing between 3-axis and 5-axis CNC machining largely depends on your project’s unique requirements. Both have their strengths and limitations.

If you need guidance on which method suits you, we’re happy to help. Our team can help you balance part complexity, production volume, cost, and quality. You can upload a part directly on our platform or schedule a meeting.