CNC milling machine: 2, 3, 4, 5 axes and differences

CNC milling is a widely used machining process for the processing of raw materials both artisanally and industrially.

Usually, the material to be machined is fixed on the worktop and the tool (milling machine) moves around the workpiece to shape it. CNC milling is a material removal process that can be used for engravings, sculptures, prototypes and anything that requires high quality and precision manufacturing.

The number of machine axes may vary depending on the size of the machine and the type of machining required. 

In general, the CNC milling machine has a minimum of 3 axes up to a maximum of 7, although the most used machines are those with 2 up to 5 axes.

Let's see together the differences in machining with 2, 3, 4 and 5-axis machines.

2-axis milling machine

The number of axes affects the movement capabilities of the milling machine. In the case of the 2-axis milling machine, this can only be moved on dimensions X, Y. The machining is therefore limited to the horizontal and vertical direction, leaving aside the depth of the workpiece.

It is also possible to have 2.5 axes, i.e. a machine that works on X, Y and where Z (the depth) is only partially possible since the movement is not interpolated to the other 2 dimensions.

3-axis milling machine

As anticipated in this case, the machine is able to machine the blank on the 3 main dimensions: horizontal (X), vertical (Y) and depth (Z). Unlike the 2.5-axis machine, the third axis is interpolated to the X and Y axes and is able to act in coordination with their movements, guaranteeing greater efficiency and precision. 

4-axis milling machine

The 4-axis CNC machines process the workpiece in a very different way compared to the previous two. In the case of 2 and 3 axis machines, the material is fixed to the worktop and machined by the milling machine, which moves around the workpiece. 

For the 4-axis machine, on the other hand, two processes are possible: 4 interpolated axes and 4 indexed axes. In the first case, the machining of the 3 axes (X, Y, Z) takes place simultaneously with the movement, while in the second case the rotation only takes place when the 3 axes are stationary. 

5-axis milling machine

The 5-axis machining allows an additional level of machining both in terms of capacity and precision. 

In this case, in addition to the movement of the axes, it is also possible to move the tool head (cutter) and the worktop. This means greater versatility of operations for machining the workpiece thanks to exceptional flexibility. In fact, all these movements are interpolated with each other in order to guarantee the precision of the processing and speed of execution.

Conclusions

Each CNC machine can machine the workpiece starting with a minimum of 2 up to a maximum of 7 axes.

The axes are what allow the machine to move the piece on several planes in order to ensure the removal of the material on all surfaces of the material.

Therefore, the greater the number of axes, the greater the machine's ability to shape the piece according to the customer's requests.