In industries such as automotive and aerospace, there is a growing demand for manufacturing high-precision parts. To meet these needs, 3+2 axis CNC processing can achieve high-quality  and efficient part production. Compared with full 5-axis processing, it can achieve these advantages without increasing complexity.

In this article, we will introduce what 3+2 axis CNC machining is and its basic knowledge. We will also explore the advantages and applications of this important machining method.

 

CNC processing Axes

CNC machine tools are classified according to their rotational and linear motions. There are three basic types of linear motions, including the X-axis (left to right), Y-axis (front to back), and Z-axis (top to bottom). To position the cutting tool at different angles, modern CNC systems also include rotational axes (A, B, and C). The A-axis rotates around the X-axis, the B-axis rotates around the Y-axis, and the C-axis rotates around the Z-axis.

Machine tools with only three axes (X, Y, and Z) are typically used to manufacture simple parts on a single plane. Adding a fourth axis (A-axis) enables multi-face processing by rotating the workpiece. Meanwhile, 5-axis machine tools also include the B-axis and C-axis, allowing simultaneous rotational and linear movements of the cutting tool. This feature makes it possible to machine complex shapes with fewer setups.

3+2 axis CNC processing

3+2 axis CNC processing is often referred to as positional 5-axis machining, which combines the precision of traditional 3-axis milling with two additional rotational axes (A and B). In this method, the workpiece is positioned and locked at a specific angle instead of rotating continuously. This arrangement allows for multi-face processing through fixed positioning.

 

The working principle of 3+2 axis machining

3+2 axis machining is a solution that lies between basic 3-axis milling and 5-axis simultaneous machining. Here are some details about the actual operation of this process.

Machine Configuration and Setup

First, the workpiece is fixed on a tilting rotary trunnion or a rotary worktable. This equipment provides two additional rotational axes (usually A-axis and B-axis). Unlike 5-axis machine tools, these rotational axes do not move continuously. Instead, they are locked at fixed angles (such as 30°, 45° or 90°) via hydraulic clamps or servo motors.

Then, the spindle positions the cutting tool perpendicular to the surface to be machined. This arrangement allows the use of smaller and harder tools, thereby reducing tool vibration and deflection.

Machining Process

After the axes are fixed, the CNC machine tool performs 3-axis milling operations along the X, Y, and Z axes. The angular direction remains unchanged throughout the cutting process.

To machine multiple sides of the part, the rotary axes reposition the workpiece between machining operations. This repositioning eliminates the need for manual rework. With this indexing cutting mechanism, complex features such as deep cavities or undercuts can be machined in a single setup.

The advantages of 3+2-axis machining

Better Tool Accessibility

3+2 axis machining utilizes two rotational axes to position the cutting tool at specific angles. This positioning method allows you to use sturdier and smaller tools to machine hard-to-reach areas such as steep walls and deep cavities. Due to the smaller tool size, there is less deflection, resulting in higher dimensional accuracy when machining complex geometries.

Cost-Effectiveness

Compared with 5-axis simultaneous machining, 3+2 machining requires simpler programming and has a lower initial cost. In addition, this method can also reduce material waste and tool wear, thereby further lowering the overall production cost.

Improved Precision and Surface Finish

In 3+2 axis machining, chatter and vibration are reduced because the cutting tool is fixed in an optimal position. As a result, the machined parts have tighter dimensional tolerances and better surface finish.

Reduced Setup Time and Increased Efficiency

In 3+2 machining, you can machine multiple surfaces without repeatedly repositioning the workpiece. This processing method can shorten the processing cycle and improve production efficiency.

The applications of 3+2-axis machining

auto industry

 

In the automotive industry, 3+2 axis processing is commonly used to produce complex components such as valve bodies, transmission housings, and engine parts. Thanks to its ability to reduce the number of setups and improve production efficiency, this technology is highly useful for high-performance automotive applications.

medical industry

 

In the medical field, 3+2 axis machining is crucial for manufacturing surgical instruments and implants (e.g., knee and hip replacements). The precision achieved through this process ensures perfect design and biocompatibility, meeting the strict standards of the medical industry.

aerospace industry

impeller

3+2 axis machining is frequently employed in the aerospace sector to manufacture structural components, turbine blades, and engine parts. This technology is well-suited for processing chamfers, compound angles, and steep walls. Consequently, it can deliver better surface finishes and tighter tolerances to meet stringent safety standards and aerodynamic performance requirements.

mould making

3+2 axis processing offers significant advantages when producing molds with deep cavities and complex shapes. The use of small tools can reduce the risk of deformation, thereby enhancing the reliability and precision of complex molds.

 

3+2 axis vs. 5-axis processing

Advantages and Disadvantages of Each Method

With 5-axis simultaneous processing, you can achieve higher precision, fewer setup operations, and the ability to complete complex parts in a single setup. However, this method requires a larger initial investment. You also need operators with professional knowledge and advanced programming skills.

On the other hand, 3+2 axis machining is more cost-effective and involves simpler programming. The drawback is that additional setups may be required when machining complex or intricate parts.

How Do the Operations Differ?

In 5-axis simultaneous processing, all five axes move continuously throughout the processing process. In contrast, 3+2 axis machining first uses the two rotational axes to orient the workpiece at a specific fixed angle. Then, the machine tool performs standard 3-axis cutting operations without further rotation.

 

Decision-making factors when choosing “3+2” or “5”

You need to consider the complexity of the part, the available budget, and specific production requirements. 5-axis simultaneous machining is ideal for industries requiring extremely high precision, such as the medical or aerospace sectors.

On the other hand, 3+2 axis machining is suitable for relatively simple parts or when cost reduction is a key priority.

Feature	5 – Axis Simultaneous Machining	3 + 2 Axis Machining
Complexity	Complex programming and setup	Simpler programming
Coût	Higher	Reduced
Operation	Continuous motion of all 5 axes	Fix the tool angle and perform 3 – axis cutting
Précision	Highly suitable for highly complex shapes	Suitable for less complex geometries
Setup Time	Most parts can be set up individually	May require multiple setups
Tool	Shorter tools with dynamic angle adjustment function	Shorter and stiffer tools

The limitations of 3+2 axis machining

Machine Tool Limitations

Unlike full 5-axis processing, 3+2 axis machining systems cannot perform continuous motion. This limitation reduces flexibility in the production of complex parts. If a part has inclined features or deep cavities, the workpiece must be repositioned multiple times. Such repositioning increases setup time, which negatively impacts overall efficiency.

Programming Difficulty

Advanced CAM software is required to program 3+2 axis machine tools for efficiently handling multiple inclined workplans. It is not as complex as simultaneous 5-axis machining but still requires careful planning. Without proper planning, tool paths may overlap. This overlap can reduce surface quality and lead to extended processing time.

Maintenance and Calibration

Your 3+2 processing equipment includes additional rotational axes that require precise calibration and regular maintenance. Accurate calibration is crucial to avoid misalignment in tool or workpiece positioning. Misalignment can result in dimensional inaccuracies, ultimately affecting the quality of the finished product.

 

Sommaire

In short, 3+2 axis CNC machining provides an economical and flexible approach to manufacturing complex parts, while improving efficiency and precision. By reducing the number of setups and optimizing processes, it simplifies the production workflow.