What's the difference between 3-axis, 4-axis & 5-axis milling?

At CloudNC, we have a range of state of the art 3-axis, 4-axis and 5-axis milling machines. As a designer, having an understanding of which type of machine your part will be manufactured on is critical in optimising your design. When designing a CNC machined part, you might not have thought about which type of machine your part will be machined on, but the complexity and type of geometry you can design will be different for different types of machines.

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The main difference between 3-axis, 4-axis and 5-axis machining is the complexity of the movement both the workpiece and the cutting tool can move through, relative to each other. The more complex the motion of the two parts, the more complex the geometry of the final machined part can be.

3-AXIS MACHINING

The most simple type of machining, where the workpiece is fixed in a single position. Movement of the spindle is available in the X, Y and Z linear directions.

3-axis machining

3-axis machines are typically used for machining of 2D and 2.5D geometry. Machining of all 6 sides of a part is possible in 3-axis machining but a new fixturing set-up is required for each side, which could be expensive (more on that below). For a single fixture setup, only one side of the part can be machined.

A unique setup is required for each side of a part

Many complex and practical shapes can be manufactured by 3-axis CNC milling, especially when in the hands of a world-class CNC machining facility. 3-axis machining is best suited to manufacture of planar milled profiles, drillings and threaded holes in-line with an axis. Undercut features are possible with the use of T-slot cutters and Dovetail milling cutters.

However, sometimes the designed feature physically cannot be manufactured by a 3-axis machine, or the feature might be more economically viable to machine with a 4 or 5-axis machine.

Features not possible in 3-axis milling include any features on an angle to the X-Y-Z co-ordinate system, even if the feature itself is planar. There are two types of angled features you can design, and understanding the distinction between them is important when designing parts for CNC milling.

ANGLED FEATURE

This is a feature machined on an angle to one of the X, Y or Z axes. For example, the planar milled surface below is at 45° to the X-axis e.g. a rotation of the A-axis.

Milled feature angled in a single plane at 45°

COMPOUND ANGLE FEATURE

This is a feature machined on an angle to two axes. For example the planar milled surface below is machined at a 45° angle to the X-axis, and a 30° angle to the Z axis.

Both angled and compound angle features cannot be machined by 3-axis CNC machines.

4-AXIS MACHINING

This adds a rotation about the X-axis, called the A-axis. The spindle has 3 linear axes of movement (X-Y-Z), like in 3-axis machining, plus the A-axis occurs by rotation of the workpiece. There are a few different arrangements for 4 axis machines, but typically they are of the &#;vertical machining&#; type, where the spindle rotates about the Z axis. The workpiece is mounted in the X-axis and can rotate with the fixture in the A-axis. For a single fixture setup, 4 sides of the part can be machined.

4-axis machining can be used as a more economically viable way of machining parts theoretically possible on a 3-axis machine. As an example, for a part we recently machined we found that using a 3-axis machine would have required two unique fixtures at a cost of £ and £800 respectively. By utilising the A-axis capability of 4-axis machining, only one fixture was required at a cost of £. This also eliminated the need for fixture change-overs, reducing costs even further. Eliminating the risk of human error meant we machined the part to a high quality with no need for expensive Quality Assurance investigations. Removing the need to change fixtures has the additional benefit that tighter tolerances can be held between features on different sides of the part. Loss of accuracy due to fixturing and re-setup has been removed.

Complex profiles such as cam lobes can be machined on a 4-axis machine

There are two types of 4-axis CNC machining: indexing and continuous.

Index 4-axis CNC machining is when the 4th axis (A-axis) rotates whilst the machine is not cutting material. Once the correct rotation is selected, a brake is applied and the machine resumes cutting.

In continuous 4-axis machining, the machine can cut material at the same time as the A-axis rotation, simultaneously. This allows complex arcs to be machined, such as the profile of cam lobes, and helixes.

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4-axis machining gives us the ability to machine angled features, otherwise not possible with a 3-axis machine. Bear in mind that 4-axis machining allows a single axis of rotation per fixture setup, so all angled features must be angled about the same axes, or additional fixtures put in place.

Helical machining possible with 4-axis machines

5-AXIS MACHINING

These CNC milling machines utilise 2 of the 3 possible rotation axis, depending on the type of machine. A machine will either utilise a rotation in the A-axis and C-axis, or a rotation in the B-axis and C-axis. The rotation either occurs by the workpiece, or by the spindle.

There are two main types of 5-axis CNC machines: 3+2 machines, and fully continuous 5-axis machines.

In 3+2 axis machining two rotational axes operate independently to each other, meaning that the workpiece can be rotated to any compound angle in relation to the cutting tool for features to be machined. However, two axes rotation at the same time as machining is not possible. 3+2 machining can produce highly complex 3D shapes. Fully continuous 5-axis machining can simultaneously rotate the two rotation axis, at the same time as machining and the cutting tool moving linearly in XYZ co-ordinates.

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5-axis machining

Continuous 5-axis machining can produce highly complex 3D shapes, not only planar compound angled features but complex curved 3D surfaces, giving us the ability to produce parts normally reserved for moulding processes.

5-axis machining gives designers a huge level of flexibility to design very complex 3D geometry. Understanding the possibilities of each type of CNC machining is essential in design of CNC machined parts. If your design needs the use of a 5-axis CNC, make the most of it! Which other features could benefit from the capabilities of 5-axis machining?

At CloudNC, we&#;re working on software to make machining simpler &#; automating large parts of the journey and helping people with less experience use CNC machines like an expert can. If you&#;d like to know more, why not check out our technology to view our CAM Assist solution, watch a video about where we think our solutions can take us, ur mission and vision, or take a look at our careers page!

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What&#;s the Difference Between 3-axis, 4-axis, and 5-axis Milling?

These days, CNC technology has evolved to include touchscreen controls, robots, and multiple-axis machines. For those that are brand new to the world of machining and bringing your manufacturing in-house, it&#;s daunting to figure out what kind of equipment you need. To provide a better idea of which milling machine and capabilities are best for you, we&#;ll explain the difference between a few types of machining: 3-axis, 4-axis, and 5-axis.

What is 3-axis Milling?

For 3-axis machining, the tool can move in three distinct directions independently or simultaneously relative to the material. It can move in the X, Y, and Z linear directions. In the case of a DATRON 3-axis milling machine, it&#;s back to front (Y-axis), side to side (X-axis), and up and down (Z-axis).

3-axis machining is great for sheet milling parts like panels and enclosures. It&#;s often used to make 2D and 2D.5 geometry. If you need to machine multiple sides of a part, that&#;s possible using multiple setups. Each orientation of the part gets set up and reconfigured in the workholding, which means more time is spent on the setups rather than milling the parts. There&#;s also more room for error with the fixture and aligning it to make sure the features are milled accurately. However, the DATRON next© control, integrated camera, and touch probe make it easy for even the most complex setups. Since precision and time are important factors in keeping production profitable, 4th and 5th axis machining may be more suitable depending on part geometry.

A 3-axis machine is well suited for operations like drilling, threading holes, cutting key slots, milling undercut features, cutting sharp angles, surface features, and features on the same plane. All these operations can also be done on 4-axis and 5-axis machines; the choice between them ultimately depends on your workflow, application, and budget. Complex geometries can be machined with 3-axis milling, but depending on the part&#;s geometry, 4-axis or 5-axis machining may be faster or necessary to reach certain features. If you need to make features that are on an angle to the XYZ coordinate system, 4th and 5th axis milling may be quicker and more precise.

What is 4-axis Milling?

There are different variations for 4-axis machining, but we will talk about vertical 4-axis milling. 4-axis machining has the same 3 axes (XYZ) as 3-axis, plus an additional axis for rotation. With a DATRON machine, it&#;s the A-axis. The A-axis has the workpiece rotate around the X-axis. The rotation allows 4 sides to be machined while the part stays in the fixture and needs only one setup.

There are 2 types of 4th axis milling: indexing and simultaneous (this is also the case for 5th axis milling). Indexing in 4-axis milling, known as 3 + 1, has the workpiece rotate into a position where 3-axis milling strategies are then used. For simultaneous machining, the part rotates, and the machine cuts it at the same time.

More complex geometries, like arcs and helixes, can be achieved more efficiently with 4th and 5th axis machining. You&#;re also able to cut angled features more easily. However, because the piece is secured in a single setup for 4th axis, the angled features need to be on the same axis. Otherwise, with different angled features, you adjust the setup (and possibly change the fixture) for each angle.

4th axis machining is often used when cut-outs and holes are on the side of a part or made on a cylinder. By using 4-axis instead of 3-axis, you typically save more time because you&#;re eliminating the need for additional setups. It&#;s also easier to hold tight tolerances on all 4 sides of a part since it stays in a single setup.

What is 5-axis Milling?

Like 4th axis machines, 5th axis machines also have their variations. The machines typically either use a rotation in the A-axis and C-axis or a rotation in the B-axis and C-axis. Both the workpiece and the spindle rotate in 5-axis milling. The two main types of 5-axis machining are simultaneous and 3+2 index milling.

For simultaneous milling, the cutting tool is in XYZ coordinates at the same time as the other two axes (A and C or B and C). This method allows highly complex 3D shapes and curves to be made. 3+2 does not have the two axes rotating at the same time. Instead, the rotation axes operate independently of each other, and the workpiece rotates to an angle in relation to the cutting tool. 5-axis machining allows manufacturers to create parts that were normally made using molds.

So, does this mean you need a separate machine for each type? Not necessarily. By adding trunnions or rotary axis accessories, 3-axis milling machines gain 4th and 5th axis milling capabilities. This is the case for DATRON CNC machines.

The DATRON neo, M10 Pro, and Cube Series are 3-axis milling machines available for upgrades with DATRON accessories. The M10 Pro and Cube series&#; machine beds have cut-out options for 4th or 5th axis accessories. The neo can do 4-axis milling with a rotary axis accessory. There is even a 5th axis DATRON machine, the C5, which is used for micromachining small, precision parts.

Our DATRON experts help many customers bring manufacturing in-house. Reach out to our team to see which machine and accessories are the right fit for your parts.

Contact us to discuss your requirements of 6 axis cnc milling machine. Our experienced sales team can help you identify the options that best suit your needs.