What does an axis mean in the case of a CNC machine?
The axis is stating how many directions the cutting tool of the CNC machine can move. Ideally, you want to have as much movement capability as possible. However, it also depends on the project; some projects don't require a lot of movement, while others do.
Normal CNC machines will have the X axis that provides horizontal movement, the Y axis for depth movement, and the Z axis for vertical movement. However, there can be more than 3-axis, with additional ones like A, B, or C, allowing rotation along the original.
Which CNC machine is ideal for you?
It always depends on a multitude of factors, such as your current production volume, but also part complexity, budget, along with precision that you need. That's why each type of machine has different use cases, as you will notice below:
A 3-axis machine is good for small companies and beginners. It's ideal if you want to work on simple parts, it's quite easy to maintain, and it has a really good cost efficiency, something you have to keep in mind.
If you need to work on jobs that are a tad more complex, with higher difficulty and a reduced setup, then a 4-axis machine is better. It's very precise and overall an improvement over the 3-axis unit, since it will help provide better balance and enhanced effectiveness. Something to consider if you want a more complex machine.
Lastly, you have the 5-axis CNC machine that's great for projects that require the utmost attention and precision. These 5-axis machines are great for medical fields, aerospace,e and any industries where complexity is a must-have, and it's certainly an impressive option to take into account.
3-axis CNC machines
What you have to know about 3-axis machines is that they are the most basic option available. But that doesn't make them bad in any way. If anything, they are good for simpler projects, small businesses, and situations where you don't need extra depth and layers in your projects. Unlike the other machines, here the cutting tool will have a stationary orientation. What moves is the workpiece, and that's why you have 3 axis for movement.
The fact that movement is restricted to 3 directions only is very important. It's offering you a variety of feature sets, and it can be used for both 2D and 2.5D machining. Due to the smaller number of axis, it can't work on 3D machining, so keep that in mind. The cutting tool will only cut in a single plane. Not a dealbreaker at all, but it certainly has its fair share of limitations.
Advantages
An upside for this type of machine is that it's very simple to program and operate. The more complexity you have in a CNC machine, the harder the operational process will be. In this case, simplicity is key.
Additionally, the maintenance is very simple, and the costs themselves are lower. It's the most affordable option if you want to focus on getting a CNC machine.
You can use it for stuff like drilling, basic milling, but also and engraving task as well. That offers a lot of versatility, while maintaining a high level of advantages.
Generally, it's meant to be great at creating parts with simple geometry. When you try to make stuff that's more complex, you will be better off going with the other types of machines.
Limitations
We should note the fact that these machines are limited to simple geometries. Even if it doesn't seem like a huge deal, if you want to work on more complex projects, the 3-axis might not be enough. That's why you want to assess the project you want to work on beforehand.
It doesn't handle complex contours or undercuts very well, which could be a problem depending on the use case.
Since it has a simple setup, creating an intricate part requires a lot of setup and changes. You will do much better if you go with something complex if you need intricate parts.
It's clear that a 3-axis machine is more suitable for beginners, but it's versatile enough and full of great features. If you're a beginner, you don't really want to invest in something complex right off the bat. It's much better if you start off small, and a 3-axis machine is more than perfect for that. Plus, if you want to work on stuff like plates, engraving signs, drilling holes or milling, it's a standout option to consider.
4-axis CNC machine
If you need to work on stuff that's a tad more complex, we think the 4-axis CNC machine is an excellent candidate. For starters, it adds an A axis which helps the workpiece rotate more effectively. What that additional axis does is it enables you to machine on multiple sides, all without manually changing its position.
That's what you would need to do in the case of a 3-axis machine, and that process is extremely time-consuming. With this additional axis, you automate that, and it helps speed up the entire project creation process a lot more than you might expect. That A axis can be used for indexing, along with continual rotation. What's great about this extra axis is that it helps you machine around the cylindrical objects, which normally would be very hard to do for a 3-axis machine.
What we noticed when using a 4-axis machine is that it's designed to be very reliable, effective, and great for more complex projects. It can be used by a beginner, however it's a good idea to get started with 3-axis machines as a newcomer and then move on to something more complex. That helps reduce any chances of error, and it will help deliver a more consistent result every time.
Advantages
Normally, a 3-axis machine will be limited, so adding another axis brings in front a new dimension and new ways for you to interact in a way that's consistent and comprehensive.
It also helps reduce the number of setups you have to do. Everyone that worked with a CNC machine knows that complex projects are very difficult to set up if you just have 3 axis to work with. The 4-axis machine circumvents that and it offers you wans to work on all kinds of objects, even cylindrical ones.
It delivers great efficiency and accuracy while also offering an exceptional quality and attention to detail.
Additionally, a 4-axis machine allows you to focus less on manual repositioning. It automates that process, which, as we said, is an exceptional way to save time and effort. That alone is worth migrating from a 3-axis to a 4-axis option.
Limitations
Naturally, when you talk about adding an extra axis to the machine, that will increase the cost. On top of that, it does become more difficult to operate, which can prove to be a challenge. But all in all, it's still worth considering if you have a complex project.
The programming and setup process is more challenging due to the complexity. It's not impossible, obviously, but you do need some previous knowledge and training to handle everything appropriately in this situation.
Despite the fact that it's more complex than a 3-axis unit, it's less complex than a 5-axis CNC machine. So yes, it still has limitations. But if you want to work on complex stuff, it's still a middle-of-the-road solution, and you're getting a very good bang for your buck with this one.
It's very important to keep in mind that with the 4-axis CNC machine, you can easily create all kinds of cool projects. For example, you can engrave on cylindrical objects, or you can easily create splines and gears. It also allows you to machine multiple sides of an item with just a single setup. It truly helps speed things up while ensuring you have a professional result.
5-axis CNC machines
These 5-axis machines are the most complex, because you have not one, but 2 additional rotational axes, more specifically B and C to the 3-axis configuration. That means you can easily work on the desired item from any direction. It just becomes a more complex workflow, while still conveying a great sense of effectiveness and value.
Moreover, you can have simultaneous machining on multiple axis. That's available only on this kind of setup, and it shows the exceptional value you can get from this type of machine. To make things even better, you can work on very complex geometries that would be very hard to access for any other type of machine.
Setting it up can be complex; it always depends on the projects. Granted, you can work on simple stuff, but also on precision-focused projects. That's what makes the 5-axis machine the most versatile option on the market. It's by far an excellent solution and the value that it provides is outstanding.
Advantages
A lot of people go for 5-axis machines because they deliver the ultimate value when it comes to precision and flexibility. No other CNC machine is as versatile and as flexible as this one, and that's the thing you want to focus on the most.
You will have a major reduction when it comes to the number of setups that you need to do. It helps make things better and that alone can prove to be a game changer.
Thanks to the way it works, the 5-axis machine will offer a very high-quality finish for the work surface. That's because it has very good tool orientation, and that will help more than expected.
You can start machining complex undercuts and contours. That's going to help you improve your workflow while ensuring that no project will be hard to work on.
Limitations
The calibration and setup process can take a while, due to the complexity of these projects.
You need advanced programming and operators with a lot of skill. Needless to say, this is not something for newcomers, and that's an important part of the process.
It requires quite a bit of maintenance, due to the complex projects you are working on.
Lastly, the acquisition price can be prohibitive for regular users, and thus it's more geared towards professional use.
The 5-axis machines can be used for automotive and aerospace components, but also for medical devices and implants. You can also use them for intricate dies and molds. Plus, these machines are often used in stuff like high-end production and prototyping.
CNC machine comparison table
| Features provided | 3-axis | 4-axis | 5-axis |
| Applications | Suitable for simple parts | Can work on moderate complexity parts, including cylinders | Any type of part, even those with very complex geometry |
| Axes of movement | X, Y, Z | X, Y, Z, and A | X, Y, Z, along with A, B and C |
| Programming | Easy to program | Medium complexity | The most complex |
| Machining speed | The slowest | Faster than 3-axis | The fastest machining speed |
| Setup time (for simple tasks) | Takes the most to set up | Moderate setup speed | Very quick to program |
| Pricing | The cheapest | Middle of the road pricing | The most expensive |
| Complexity | It's the easiest machine to use | It can have its difficulties, great for more complex features. | The most advanced, complex and challenging to use, but also more versatile |
How to choose 3-Axis, 4-Axis, and 5-Axis CNC machines?
When choosing a CNC machine, there are different criteria to think about. The most common criteria to cover are listed below.
Part geometry and complexity
If you want to work with holes, pockets, slows, and flat shapes, a 3-axis machine will be great. For those projects that have features on multiple faces, 4-axis machines are perfect. If you need to work with molds, turbine blades, impellers, sculpted surfaces and so on, then you need a 5-axis machine.
Setup time and production volume
In case your focus is volume and setup time, then the best option is a 5-axis machine because it has support for high volume, complex parts. 4-axis machines are ideal for medium runs with moderate complexity. 3-axis machines require separate setups for each face, so it's a slower option.
Materials to consider
Soft materials like aluminum, plastic or wood will work well with 3 or 4 axis machines. Hard metals and composites will require a 5-axis machine if you want the best possible results.
ROI and budget
You can expect to pay anywhere from $10k to $80k for a 3-axis machine. The 4-axis machines will go anywhere from $30k to $120k depending on capabilities. 5-axis machines are $100k to $500k, depending on the features. Plus, there are hidden costs like skilled labor, CAM software, fixtures and tooling, along with maintenance.
Skill level
Beginners should always start with 3-axis machines. Intermediate shops can go with 4-axis machines, and if you need fewer errors and faster machining, you will need to opt for the 5-axis machines.
Other things to consider
Always consider the coolant system, especially if you're working with metals
Tool changers matter because more tools will equal less downtime
The spindle power and speed matter, since you want to match it to the material's needs
What controller type do you use? The controller type will affect things like operator training and programming.
Lastly, the machine envelope and travel matter too, because you want to know if the machine fits the largest parts.
Conclusion
If you're looking to buy a CNC machine, then choosing between 3-axis, 4-axis, and 5-axis models is very important. As always, it comes down to what you need, the feature sets you are interested in, but also what projects you want to work on. In the end, all of them are very effective, depending on your needs. Hobbyists can start with a 3-axis machine and move on to more complex units down the line. However, if you have a larger business, a 5-axis machine is ideal because it will help with very complex parts and features!