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.
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.
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.
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
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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.
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!
Computer numerical control (CNC) machines have come a long way in less than a century of existence. The original CNC machine built in the 50s revolutionized the production of components by subtractive manufacturing across three axes, opening up the possibility for the machining of complex shapes and designs that were previously difficult or impossible to manufacture. The machines available today, with anywhere between 5 and 9 axes can produce products with unbelievably complex geometries, quickly and efficiently. To understand why, we first have to understand a bit about what it means for a machine to have multiple axes.
Take a look at the 9-Axis Swiss Lathe Center we use for part production in our shop, pictured above ›
Though technically a 3-axis cnc machine is operating on multiple axes, we typically only refer to machines of 5 axes or more as “multi-axis” as it’s at this level or higher that more complex geometries with deeper cuts can be produced. But why exactly is a higher number of axes important in machining? With fewer axes that the cutting and milling tools can ride on to approach a turning piece of bar stock, the angles that the tools can reach relative to the piece are limited. SImply put, the more axes available, the more opportunity to get closer to the stock and perform cutting operations at various angles, allowing for more complex machining without the need to move or rotate the stock material. Combined with the addition of a separate spindle and a variety of tooling, and you have a machine capable of completing complex cuts quickly, efficiently and with higher accuracy.
For this reason, investing in multi-axis CNC machining produces greater productivity and improves numerous manufacturing metrics, delivering a measurable and significant ROI through several advantages over machining on a traditional 3-axis cnc machine.
Multi axis CNC machines operate with greater precision to deliver accurately machined and smoother parts that would be difficult or even impossible to achieve with a 3-axis machine. With a traditional 3-axis cnc machine, the tooling can only approach the workpiece at a few points, limiting the angles from which the stock can be cut away.
Therefore, to create more complex parts with a 3-axis machine, the workpiece would have to be moved and repositioned for various cuts. Each time a workpiece is moved within the machining process, accuracy and precision are compromised. The multi-axis machines we have access to today can reach workpieces at various angles, and operate more closely to the workpiece, allowing for a complex array of geometries to be performed within a single setup, with no repositioning required.
The tangential arrangement of the cutting tools to the material with multi-axis machining allows for more material to be removed with each rotation, increasing the speed that single applications can be performed. When this is combined with expanded tooling capabilities and multi-axis simultaneous machining from a single setup, cycle times improve significantly. This can lead to drastically reduced lead times.
With multi axis machines, you can set up your workpieces at one time to handle all milling/turning operations needed to fabricate complex geometries. You’ll produce parts faster, minimize operational costs, and reduce most errors prevalent in conventional 3-axis machines.
The ability of multi-axis CNC machining to move workpieces over more dimensions without removing them gives it a significant advantage over conventional 3-axis machining. Cnc machines with 5 axes or more can get tools very close to the working material at various angles, creating the ability for deep cuts and complex shapes that were not achievable from only 3-axes machines. The greater the axes, the better the machine can handle complex designs with high precision.
Any time a workpiece needs to be repositioned for a separate set of cutting operations, a degree of precision is lost. High level multi-axis cnc machines, like our 9-axis Miyano, deliver the most complex parts with extreme precision. These machines attack the most complicated angles to create complex geometries with premium finishes at tighter tolerances.
Multi axis machines bring the cutting tools closer to the working material. Shorter cutting tools produce better surface finishes because the shortened length makes them less susceptible to machining vibration. This produces a cleaner product directly from the machining process and minimizes the need for additional touch ups.
Multi-axis cnc machines change the game for drilling applications. Each time a part is moved in a CNC operation, there’s an opportunity for error or loss of precision. Since parts hold their position through various applications in multi-axis machining, precision is maintained even through separate drilling applications with different variants. The additional axes also allow the machine to reach tighter and more complex angles, completing more complex drilling applications with finer finishes.
Multi-axis machining is the name of the game for any production that requires a high level of accuracy and precision of its parts, without fail. This could apply to nearly any industry in manufacturing; however, there are a few that rely on multi-axis machining more regularly than others, such as the following:
Contact us to discuss your requirements of 3 Axis Machining Center. Our experienced sales team can help you identify the options that best suit your needs.