CNC (Computer Numerical Control) machines are used in manufacturing to automate the operation of various machine tools, So it is important to have a good understanding of What are the advantage and disadvantage of the different types of CNC machines? Because if you’re not familiar with the advantage and disadvantage of each different type of CNC machine, you might not be able to design for it properly and that’s really what ends up costing a lot of time and money. that’s why today what we’re gonna be covering is how the machines work and the limitations and benefits of each different machine type.
Categories or CNC machine types
The type of CNC machine depends on the movement of cutting tool and workpiece. general speaking, CNC machines can be broken up into two main machine types, 3 axis CNC machine and multi axis CNC machine. 3 axis machines are cnc milling or CNC turning machines also is it commonly referred to as lathe. the multi axis CNC machines can be indexed 4-axis, 5-axis machine and mill turning machine.
3 axis CNC machines
3-axis CNC machining is among the most common manufacturing processes because they’re easier to program and operate. They lead to a relatively low machining start up cost. when required 3 axis CNC milling machines are very common because they can produce most standard geometries.
CNC milling machines and CNC turning machines allow the movement of the cutting tool relative to the workpiece in 3 linear axes，The cutting tool can move side by side (the x-axis), front and back (the y-axis), and up and down (the z-axis). During CNC milling, the workpiece is held stationary directly on the machine bed or in vise, material is removed from the workpiece using specialized cutting tools that rotate at a very high speed, the cutting tools are attached to a spindle which can move along the 3 linear axes just discussed. usually, Several rounds of cutting are applied to produce the part, first, an approximate geometry is given to the workplace intended removing material quickly at a lower accuracy. Then one or more finishing rounds are used to produce the final part.
CNC lathes can produce parts at a much higher rate, and at a lower cost per unit than cnc mills, Especially relevant for larger volume. The process is quite different from how milling works. It is workpiece rotating around the fixed cutting tool instead of the tool rotating. CNC turning the workpiece is held on the spindle while rotating at high speed. a Cutting tool or centet drill traces the outer an inner perimeter forming the geometry, holes along the center axis also be manufactured using center drills and internal cutting tools. Typically, CNC lathes are used to produce parts with a cylindrical profile. This is also the downside. They can only produce that geometry.
However, the 3-axis CNC system comes with some limitations as well. because there are 3 axes, certain areas might be impossible to reach. To overcome this limitation. Features of the part are often seen see milled in a separate machine step. The workpiece need constant reorienting and resetting for more complicated shapes. but multiple resetting can increase your machine and labor costs. For such applications, you’ll need to opt for multi-axis machines as they address the shortcomings of the 3-axis system and are more versatile. Multi-axis machines can be used to produce the same geometry in one step.
4-axis CNC machines
Let’s talk about 4-axis machine first. 4-axis machines can rotate on the same three linear axes as 3 axes cnc machines. And it allow the workpiece to rotate along the x-axis or Y-axis. You’ll find the two kinds of 4-axis CNC machines called indexed 4-axis(3+1) machine and continuous 4-axis machine. The biggest difference between them is continuous 4-axis machine much more advanced and productive as it can cut material at the same time as the A-axis rotation,This opens up a lot of possibilities as the added rotation can enhance your productivity by eliminating the need for reorienting and resetting.
4 axis machining gives us the ability to machine angled features, otherwise not possible with a 3-axis machine. But all angled features must be angled about the same axes, or additional fixtures put in place. So for parts with features in more axes, we must rely on more flexible 5-axis machine.
5 axis CNC machines
What makes 5-axis machine different is that it can rotate on an additional two axes, making five axes in total. The ability to rotate in two ways gives unlimited freedom to the machine and virtually removes most of the limitations of this process. the increased flexibility and enhanced operational efficiency can definitely do wonders for your productivity.However, the numerical codes and designs obviously get more difficult with 5-axis CNC machines. this does come with an increased cost, because it requires specialized machinery and operators with expert knowledge.
Indexed 5-axis CNC milling machines
You’ll find the two kinds of 5-axis CNC machines called indexed 5-axis CNC milling machines(3+2) and continuous 5-axis CNC milling machines. 3+2-axis CNC milling machines are a tad more advanced than their 4-axis counterparts. During machining, the cutting tool can only move along 3 linear axes. However, between operations, the bed and the tool head can rotate automatic, giving access to the workpiece from a different angle. Because of this, no manually reposition the workpiece parts with more complex geometries, Can therefore be manufactured faster and at a higher accuracy than the 3- axes or 4-axis CNC mill. But they lack the true free form capabilities of a continuous five axis CNC machine.
Continuous 5-axis CNC milling machines
Continuous 5-axis CNC milling machines have very similar architecture to indexed 5-axis CNC machines. but there is one big different is continuous 5-axis CNC milling machines allow for the movement of all 5 axes, at the same time during all machining operations. but These advanced capabilities come at a high cost with continues 5-axis CNC milling, because there are 3 types of swivel head with rotary table, Trunnion table design and traveling column design 5-axis operations that you can opt for. All these machines can give the same results. However, the way you’ll program them and deal with them would be different, you need expensive machines and highly trained machinist to accurately program the machines. Finally, we have CNC milling-turning machines.
CNC milling-turning machines
CNC milling-turning machines are an advanced option that is not restricted in
their operations. CNC milling-turning machines are exactly like CNC turning machine, Only they are also equipped with CNC milling tools. The workpiece is attached to a spindle that can either rotate at high speeds or position it at a precise angle. Like a 5-axis CNC mill lathe and milling cutting tools are used. Thereby, increasing the overall possibilities and capabilities of the machine. However, CNC milling-turning machines are both expensive and difficult to manage. That’s why many experts rely on separate CNC machines whenever the situation permits.
Swiss screw machines
A variation of the CNC milling-turning machines called swiss screw machines, they take advantage of both the high productivity of CNC turning system and the geometric flexibility of CNC milling systems to machining high precision small size parts. It is obvious that swiss screw machining has very high processing efficiency.
Conclusion
Familiar with the dvantage and disadvantage of the different types of CNC machines is helpful for you to choose the appropriate processing technology. 3-axes CNC milling machines manufactured parts with relatively simple geometries with excellent accuracy and as a low cost. CNC turning machines have the lowest cost per unit, but are only suitable for part geometries with cylinder object, Indexed 5-axis CNC milling machine manufactured parts with features that do not align with one of the main axes quickly and with very high accuracy. Continuous 5-axis CNC milling machines, manufactured parts with highly complex organic geometries and smooth contours but at a high cost, CNC milling-turning machines combine the benefits of CNC turning to manufacture complex parts. At a lower cost than 5-axis CNC systems. swiss screw machines suitable for processing small precision parts.