3-Axis to 12-Axis: CNC Milling Machine Capabilities Compared and Applications

This blog is a deep dive into multi axis CNC milling – what the machine options are, how to apply them and how to get the best from your equipment.

CNC mills are computerized manufacturing machines that travel cutting tools on a variety of axes of travel, to shape and cut materials such as metal, wood, plastics, and composites into precision parts that faithfully reproduce a CAD design file.

CNC stands for Computer Numerical Control, which means that the machine is operated using a program that controls the movement of the cutting tools.

CNC milling machines are capable of performing a wide range of operations, including drilling, boring, tapping, and contouring, and can produce complex shapes with high precision and accuracy. They are used in a variety of industries, including aerospace, automotive, medical, and consumer goods manufacturing.

The process begins with a computer-aided design (CAD) file that contains the design specifications for the part or component that is to be produced. The CAD file is then converted into a computer-aided manufacturing (CAM) program that generates the toolpaths for the CNC machine to follow.

The CNC milling machine is equipped with a cutting tool that is controlled by a series of motors and drive systems. The cutting tool moves along the basic X, Y, and Z axes, but various machine types allow other varieties of travelers – both of the cutter and the workpiece – to provide greater freedom in cutting away material.

The speed and direction of the cutting tool are controlled by the CAM program, which is stored on a computer connected to the machine or directly on a control panel the user operates through.

CNC milling machines are capable of producing parts with very tight tolerances, which means that the finished part is very close to the original design specifications. They are also capable of producing large quantities of parts quickly and efficiently, making them a popular choice for high-volume manufacturing applications.

Overall, CNC milling is a highly precise and efficient manufacturing process that has revolutionized the way that parts and components are produced.

I.Types of CNC Machine Axes

CNC machines are categorized by the degrees of freedom of motion of the cutter and the workpiece. These are generally quantified as axes of motion;

3-Axis CNC Machining

The three axes refer to the X, Y, and Z axes, which allow the cutting tool to move on two horizontal planes and vertically.

The X-axis runs horizontally across the machine from an operators perspective, the Y-axis runs horizontally at 90° to the X axis, and the Z-axis runs vertically, allowing the cutting tool to move up and down. The movement of the cutting tool in all three axes is precisely controlled by the CNC program.

The 3-axis CNC milling machine can be used to machine a variety of materials, including metals, plastics, and wood, and is able to produce parts with intricate shapes and features. It is also versatile and can be programmed to perform a range of machining operations, such as drilling, milling, and boring.

Some of the advantages of using a 3-axis CNC milling machine include increased productivity compared with manual machines, improved accuracy and repeatability, and the ability to produce multiple complex parts without additional setup.

3 axis machines are limited in motion, so there are various forms that it cannot produce, or cannot make efficiently due to workpiece repositioning and additional setups.

4-Axis CNC Machining

A 4-axis CNC milling machine also includes a rotary axis, sometimes referred to as the A axis. This allows the workpiece to be rotated on one axis of rotation while clamped into the machine, allowing increased access for the cutter.

The rotary axis is usually positioned parallel to the X-axis and allows the material to be indexed through angular settings.

This functions in the same way as a dividing head on a manual mill, allowing movement to a new fixed angular position – it generally does not allow the material to be spun as if in a lathe and the cutters are rotating types rather than typical stationary lathe types.

This capability makes it possible to present the cutting tool to reach areas that are not accessible with a 3-axis CNC milling machine, and makes it possible to create more complex geometries and curved surfaces.

5-Axis CNC Machining

A 5 axis CNC milling machine has a second rotary axis that sits perpendicular to the primary rotary axis that is the defining characteristic of a 4 axis machine, operating in exactly the same way and referred to as the B axis.

The cooperative motion of the two rotary axes allows the material to be rotated in two perpendicular directions, which makes it possible to machine the material at even more complex angles and to create more complex geometries and curved surfaces.

This enables the cutting tool to reach areas that are not accessible with a 3-axis or 4-axis CNC milling machine.

The increased capability comes at an increased price for the equipment and additional complexity/skills requirement in operation.

7-Axis CNC Machining

The 7 axis machine is a significantly more complex device than the 5 axis machine it developed from.

The 6th axis is a third axis of rotation of the material being worked on, allowing it to be rotated on axes in the X, Y AND Z planes.

The 7th axis is simple motion that allows the workpiece to be spun on one axis, as if in a lathe. This hugely increases the capabilities of the machine, in that it can combine mill and lathe functionality in a single machining center. This type of lathe-like cutting can be performed both by rotary cutting tools and by more traditional, stationary lathe cutting tools.

7 axis machines are generally robot arm based, rather than classical machining centers, but both types are employed.

9-Axis CNC Machining

Definitions and specifications of 9 axis CNC machining centers are more fluid and differ between suppliers and research proposals. It’s clear from all of the proposed and commercially delivered interpretations of 9 axis machines that there are a LOT of degrees of freedom to allow cutters to be introduced to material in a single setup in a wide range of directions and modes.

9 axis CNC machines step up a level, in comparison with 7 axis machines. One type, sometimes referred to as the Swiss type, provides 9 axes by combining;

Dual spindles (front and rear), providing X₁, Y₁, Z₁ and X₂, Y₂, Z₂ axes
Part movement provides X₃, Y₃, Z₃

This definition lacks reference to the rotational axes that are common in more advanced machines, the A, B and C axes.

This coordinate system is by no means the only definition of 9 axis CNC mills, another defines the 9 axes as;

A 5 axis CNC mill with axes X₁, Y₁, Z₁ plus rotational axes A and C (or B by some definitions)
Plus a 4 axis lathe, which is usually defined as;
- X motion perpendicular to the axis of the workpiece, the typical lathe cutting axis.
- Z motion along the axis of the workpiece, the traditional main slide or tailstock motion of a lathe.
- C motion around the axis of the stock. Identical to the spindle axis, this acts as a coaxial dividing head for broach cutting or off center drilling/tapping on a typical lathe.
- Y motion perpendicular to the axis of the workpiece with a rotary cutting tool in a milling head, in conjunction with the C axis for positioning.

These definitions are highly open to interpretation, and some researchers have made other proposals that are not yet embodied in functioning machines.

12-Axis CNC Machining

Strangely, 12 axis machines are more clearly defined and the coordinate systems more agreed;

This involves two independent spindles, co-working (rather than alternating), with axes X₁, Y₁, Z_1,A₁, B₁, C₁ (orthogonal and rotational axes) on spindle one and X₂, Y₂, Z₂, A₂, B₂, C₂ on the other.

II. What is 3-axis CNC Machining?

This is the most basic level of CNC milling, with three orthogonal axes of workpiece motion and a rotating tool/cutter.

Capabilities of 3-axis CNC Machining

3-axis CNC machining is heavily employed in manufacturing a variety of parts of simple to complex geometries.

Delivering high levels of precision and accuracy, down to the thousandth of an inch, with consistent, repeatable results and tight tolerances.
Manufacturing parts, from simple flat components to complex 3D shapes, often requiring multiple setups and tool changes.
Automating the manufacturing process offers great return on effort, reducing the time and labor required to produce multiple parts compared with manual machining.
CNC machine programming allows for simple changes to the code, allowing for the production of live design adjustments and minor product variations at high speed.
Once a part is programmed and validated, production of large quantities of parts with consistent quality becomes a relatively low effort task.

Advantages of 3-axis CNC Machining

Where 3 axis machines fit the typical need – as they do in 90% of components – they offer significant advantages;

Low capital cost – 3 axis machines are surprisingly inexpensive, even in relatively heavy equipment
Easy programming – the learning in setup and programming of 3 axis machines is quite simple
Low maintenance – there’s just not much to a 3 axis machine, so they’re simple to keep in good order

Applications of 3-axis CNC Machining

Some of the common applications of 3-axis CNC machining include milling, drilling, tapping, and boring operations on a range of materials such as metals, plastics, and composites. Overall, 3-axis CNC machining offers a reliable and efficient method for you to produce a wide range of parts and products, across many industries and market sectors.

III. What is 5-axis CNC Machining?

Capabilities of 5-axis CNC Machining

5-axis CNC machines offer some significant advantages over 3 and 4 axis machines;

5-axis CNC machines are capable of producing highly precise parts with tight tolerances, especially for complex and irregular shapes that require multiple machining operations. Much of this results from the reduced need to move the workpiece to a new setup position, as each setup introduces potential positional/accuracy errors.
flexibility: 5-axis CNC machines can produce complex parts from multiple angles and positions without requiring repositioning, reducing the number of setups required to complete a part.
Reducing the need for multiple setups allows 5-axis CNC machines to deliver more quickly and with higher accuracy.
The reduced need for disjointed motion in the cutter in 5-axis machines results in improved surface finishes and fewer tool marks.
Complex geometries enabled by 5-axis machines allows more intricate curved surfaces and contoured shapes.

Advantages of 5-axis CNC Machining

The ability of a 5-axis machine to work on five different faces of a workpiece at the same time is a relief for many industrial processes. That’s because the machine can do a faster job in shaping a workpiece than a 3-axis machine.
5-axis CNC machining is useful for more complex operations that the 3-axis machines can’t handle in a single operation. The machine does an amazing job of producing contours on a workpiece.
5-axis CNC machiningalso eliminates the need for workpiece repositioning while machining is in progress.
5-axis CNC machining allows for shorter cutting tools. The implication of this is that vibrations are minimal. Therefore, the surface finishing is smoother as there is little chance of the cutting tool accidentally creating marks on the surface.

Applications of 5-axis CNC Machining

Some of the common applications of 5-axis CNC machining again include aerospace and automotive parts, medical devices, and mold and die components.

Overall, 5-axis CNC machining offers a powerful and versatile method for producing complex, high-precision parts with greater efficiency and speed and can deliver a wider range of more complex geometries than the 3 and 4 axis methods.

IV. What is 7-axis CNC Machining?

Capabilities of 7-axis CNC Machining

7-axis CNC machining centers achieve a high level of precision and versatility for manufacturing complex parts with intricate shapes and geometries. The additional two axes of motion additional to a 5-axis machine provide even greater control and flexibility in cutting operations.

A 7-axis CNC machine can cut from multiple sides simultaneously, increasing throughput.
They can handle more complex geometries, including contoured surfaces, tapered features, and an increasing range of undercuts that are impossible in simpler machines.
Increased access can deliver extremely tight tolerances, with accuracy down to a few microns, as there are fewer repositioning movements required.
7-axis machines are typically equipped with higher speed spindles, allowing for more rapid and precise cutting.
The additional axes of motion in a 7-axis machine allow for greater access with more tools earlier in the machining process, reducing tool changes, and setup times.
Improved surface finish results from increased directional control and fewer stop points, delivering a higher quality surface finish on complex part.

Advantages of 7-axis CNC Machining

Overall, 7-axis CNC machining offers more advanced capabilities in part geometry, complex and compound curvature and internal cuts than simpler machines. This enables the manufacturing of complex parts with high precision and efficiency, making it a valuable technology in leading edge and complex areas of manufacturing.

Applications of 7-axis CNC Machining

Typical applications include complex surface fluid flow and power components such as gas and liquid turbine blades, intricate pump and compressor parts and high complexity medical implants. Industries making the greatest use of 7 axis CNC machining are aerospace, fluid mechanics and medical developments.

V. What is 9-axis CNC Machining?

9 axis CNC milling, under the ‘Swiss’ type definition differs from conventional (3 to 7 axis) machining in that it has dual independent spindles and a stationary workpiece

Capabilities of 9-axis CNC Machining

9-axis CNC machining centers achieve a higher level versatility for cutting parts with intricate compound shapes and hard to access geometries. The additional two axes of motion additional to a 7-axis machine allow further improvements in cutter position and tool path flexibility and optimization.

A 9-axis CNC machine, like a 7-axis machine can cut from multiple sides offering similar throughput benefits.
These machines can cope with yet more complex geometries and an increase in internal access for undercuts and internal complexities.
This improved cutter positioning and tool path maintains or improves the extremely tight tolerances of 7 axis machines, with even fewer stop/turn and disjoint moments in creating complex toolpaths.
9-axis machines are also equipped with higher speed spindles, allowing for similarly rapid and precise cutting.
Smoother toolpaths result in improved surface finish.

Advantages of 9-axis CNC Machining

The additional two axes in a 9-axis CNC machine over a 7-axis CNC machine offer several advantages, including:

The additional axes, over and above 7-axis machines, allows for more complex and intricate shapes to be machined. Parts that would be difficult or impossible to produce with a 7-axis machine can often be manufactured with a 9-axis machine.
A 9-axis CNC machine offers improved accuracy over a 7-axis machine by requiring fewer tool and workpiece movements than machines with fewer axes.
The additional axes provide greater flexibility and control over the machining process, which can be useful in applications where very complex surfaces and extreme undercuts are required.
The ability to perform multiple operations simultaneously can reduce the time required to set up and complete a job, improving efficiency and reducing costs.

Applications of 9-axis CNC Machining

Applications that commonly make use of the additional capabilities of 9-axis machines are gas turbine and compressor blades, intricate medical implants and complex dental work. 9-axis machines bring capabilities closer to delivering unrestricted organic and highly curved surfaces.

VI. What is 12-axis CNC Machining?

The definitions of 9-axis CNC machine tools may be somewhat imprecise, but 12-axis machines are very clearly defined as dual cutting heads, each with 6 degrees of freedom.

Capabilities of 12-axis CNC Machining

12-axis machines improve on 9 axis devices by offering yet more increase in cutter access and the ability to follow yet more complex curvature without additional setups.

12-axis machines have advanced the technology to the point where there are no more degrees of freedom proposed or discussed.

Advantages of 12-axis CNC Machining

12-axis machines have achieved such freedom of motion for the cutter that their abilities are essentially limited by design need/imagination rather than by machine motion.

Maximal conformance to complex curvature, there are no more degrees of freedom envisaged to improve on this
Best maintenance of precision due to reduced tool changes and repositioning movements
High speed cutters maximize productivity
Multi face machining maximizes productivity
Minimization of setups maximizes productivity

Applications of 12-axis CNC Machining

12-axis machines are expensive to buy and to operate. They are generally reserved for the most demanding and complex tasks such as experimental work in obscure military, aerospace and medical applications.

A typical example of a hard-to-cut part that a 12=axis machine is best adapted to is the experimental development of toroidal turbine and propellor blades. Small AI driven iterations are resulting in significant performance gains and these are best executed for trial on machines in this class.

VII. Difference Between 3-Axis to 12-Axis CNC Milling Machine

As the axis count increases, several commercially and technically beneficial capabilities arise and improve, to the point of almost unlimited shape capacity. With rising axis count;

the ability to deliver precise conformity with increasingly complex and convolute curvature improves. 3 axis machines can do a good job of 2D profiles and simple 3D shapes. 12-axis machines can make near truly organic shapes of perfect surface finish.
productivity rises. Auto tool changers, dual spindles, integrated lathe/mill functionality and reduced setups all amount to improving machining speed/capacity
programming gets more complex. To fully utilize a 3-axis machine is a technical task of moderate complexity. Deep understanding of multi axis machines takes more experience and a deeper understanding of the limitations of the machines
machine prices climb quickly. Basic machines are not free, but as the axis count increases, purchase, setup and maintenance costs of machines climb rapidly – but so does the value of the work they can perform

VIII. 3-Axis to 12-Axis CNC Milling Machining: Which One is Best for Your Project?

If your parts are complex, selection of the minimum specification machine to complete the tasks you need performing is a task for an experienced professional, when the parts become complicated.

In assessing a design for the required axis count, the process starts off very easy. The vast bulk of machined parts are well suited to 3, 3.5 or 4 axis machines. When the part encompasses complex and compound curvatures, very high tolerance requirements and/or aspects that lend themselves to turning (lathe work), then the process requires a subtle understanding of capabilities.

And it often requires some design compromise, because there are often features that cannot be machined, as designed.

Kemal CNC Machining Services

Kemal has the equipment, team and understanding to help you at all stages – from design assessment/optimization through prototyping and onwards to mass production.

Our in-house CNC facilities are world class and we specialize in 3 and 5 axis services, with extensive capacity and great knowledge-base.

For work in higher order machines, we work with a group of highly capable service providers and offer a seamless service – we manage the process, schedule and quality issues seamlessly.

Conclusion

Whatever your CNC machining needs, Kemal is the right partner. Contact us today for a no-strings discussion about your project, your needs and our services.