What is 4-axis and 5-axis CNC Machining?

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    What is 4-axis and 5-axis CNC Machining?

    When selecting a CNC machining service for a project, you’ll hear a lot of talk about axes. Generally, CNC machines tend to operate using 3, 4, or 5 axes, with 4 axis CNC machines and 5 axis CNC machines being the most capable kinds. However, what exactly does a 4 axis CNC machine and 5 axis CNC machine mean?

    what are 4-axis and 5-axis cnc machining?

    This article will explain the basic principles of a 4 axis CNC machine and 5 axis CNC machine and how they can help improve your machining project. It will also talk about other CNC machining axes in order for you to easily compare 3 axis vs 4 axis vs 5 axis CNC machining.

    3 Axis CNC Machining

    3 axis cnc machining

    To easily compare 3 axis vs 4 axis vs 5 axis CNC machining, there is a need to talk about each axis. We will introduce 3 axis CNC machining, which is the most widely used CNC machining axis today.

    A typical 3 axis CNC mill creates parts by moving its spindle side to side (X-axis), back and forth (Y-axis), and up and down (Z-axis), according to the illustration above. The cutting tool, attached to the spindle, cuts pieces away from the workpiece as the spindle moves along those three axes. For some machined parts, this is a perfectly suitable way to work. However, the 3-axis set-up has some severe limitations, which are:

    • The angle of the cutting tool remains uniform, pointing downwards or sideways. Therefore, it is harder to cut away parts of the material in hard-to-reach sections of the workpiece, such as crevices.
    • It might be necessary to carry out multiple set-ups for a part. For example, if the part needs machining on several sides, you may need to take out the machine, reorient it, then return it to the machine for further cutting. Naturally, the need for multiple set-ups can drastically reduce productivity.

    4 Axis CNC Machining

    4 axis cnc machining

    In 4 axis CNC machining, the spindle has the same axes of movement as 3 axis CNC machining. However, there is a rotation along the X-axis known as A-axis. 4 axis CNC machines are an ideal option for machining parts that are theoretically machinable on 3 axis CNC machines.  

    Types of 4 axis CNC machining  

    4 axis CNC machining has two major types: indexing and continuous. Below is an explanation of the types:

    • Index 4 axis CNC machining

    In the index 4 axis CNC machining, the A-axis rotates when the CNC machine is not cutting material. After selecting the correct rotation, a brake is applied, and the CNC machine resumes cutting.

    • Continuous 4 axis CNC machining

    In continuous 4 axis machining, the A-axis rotates while the CNC machine cut the material. Therefore, it allows you to machine complex arcs, e.g., cam lobes profile and helixes.

    4-axis CNC machining allows you to machine angled features which is not achievable using a 3 axis CNC machine. You must remember that in 4 axis CNC machining, there is a single axis of rotation per fixture set-up. Therefore, all angled features must be angled about the same axes, or additional fixtures put in place.

    5 Axis CNC Machining

    5 axis cnc machine

    A 5 axis CNC machine center is a lot like a 3 axis CNC machine. However, the difference between 3 axis and 5 axis CNC machining is the two extra axes which provides the 5 axis CNC machine with more cutting flexibility. So, where do those two extra axes come from?

    In a 3-axis CNC machine, the spindle travels along three axes: side to side (X-axis), back and forth (Y-axis), and up and down (Z-axis), while the workpiece remains stationary on the machine table. However, with a 5 axis CNC machine, the spindle or the table can also rotate.

    The implications of this rotation are huge. On a 5 axis CNC machine, not only can the spindle and cutting tool move along three axes, but it can also adjust its orientation (or the orientation of the workpiece) about two of those three axes.

    Rotation about the X-axis is called the A-axis, rotation about the Y-axis is called the B-axis, and rotation about the Z-axis is called the C-axis.

    A 5 axis CNC machine can utilize any two of these rotational axes, depending on its configuration. (4 axis CNC machines utilize one which is the A-axis)

    Some 5 axis machines use a trunnion table, which rocks the workpiece about two axes as the spindle moves along three axes without rotating. Other 5-axis machines use a swivel head — a spindle that moves and rotates while the workpiece remains on a stationary bed.

    Regardless of configurations, a 5 axis CNC machine can move its cutting tools in more varied ways, and from a greater number of angles, than 3-axis CNC machines. This difference between 3 axis and 5 axis cnc machines allows for more complex machining operations and increased accuracy and can eliminate the need for multiple set-ups.

    What is 3+2 Axis CNC machining?

    3+2-axis machining is a subtype of 5 axis CNC machining, also called positional 5 axis CNC machining. As its name suggests, it is a middle ground between a 3 axis and 5 axis CNC machine. It is nonetheless a rapid and highly effective form of 5-axis CNC machining.

    With 3+2-axis machining, the angle of the cutting tool does not change as the spindle or table rotates about the two extra axes. As a result, the cutting tool is not always perpendicular to the part, which does not always create perfect cuts. However, there is a form of 3+2-axis machining called indexed 3+2-axis machining, in which the angle of the cutting tool is manually adjusted between cuts.

    Simultaneous 5 Axis CNC Machining

    5-axis CNC machining in which the cutting tool can always be kept perpendicular to the part is called continuous or simultaneous 5-axis machining. This process can provide a superior surface finish and allows access to hard-to-reach areas but is slower than 3+2-axis machining.

    What’s The Difference Between 3,4 and 5 Axis CNC Machining?

    what is the difference between 3,4 and 5 axis

    Below is the summary of the 3 axis vs 4 axis vs 5 axis CNC machining debate:

    • Principle

    A 3 axis CNC machining only has X, Y, Z axes.

    4 axis CNC machines have X, Y, Z, and A axes.

    A 5 axis CNC machine has X, Y, Z and two of the A, B, C axes.

    • Processing Features

    The cutting tool direction is the same in 3 axis CNC machining during the whole cutting path.

    In the 4 axis CNC machining, there is an addition of a rotation axis for rotation. However, the axis cannot rotate at high speed.

    In 5-axis CNC machining, you can optimize the direction while moving along the whole path. Also, the tool’s linear motion can be carried out at the same time. Consequently, you can maintain the best cutting condition in the whole path using a 5-axis CNC machining tool.

    • Cost

    A 5 axis CNC machine is the most expensive of the three major types. It follows the order below 5>4>3. It is also an important factor when choosing one of them

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    Benefits of 4axis and 5axis CNC Machining

    4 axis CNC machines and 5-axis CNC machines are known to be the most capable kinds of all the machining axes. Below are a few benefits of the two CNC machining axes.

    • Complex Shapes

    This is the most popular advantage of using 4 axis CNC machine and a 5 axis CNC machine. Due to the extra movement recorded in both axes, it is possible to create machining angles and arcs for the cutting tools. Consequently, there is no need for many special fixtures or additional set-ups to achieve such settings, and you can easily machine complex shapes. However, 5 axis cnc machine is more suitable for making complex shapes than 4 axis CNC machine due to its extra rotation axis.

    • Improved Tool Life

    Using a 4 axis cnc machine or a 5 axis CNC machine results in the tilting of the cutting tool. Therefore, there is the maintenance of optimum cutting position, which improves tool life and cycle time.

    • Fewer Set-ups

    You can use both 4 axis CNC machines and 5 axis CNC machines on any surface (except the bottom and clamping area). Therefore, there is a reduction in the need for multiple set-ups or fixtures seen in the 3 axis CNC machining.

    Applications of 4 axis CNC Machining and 5 axis CNC machining

    4 axis CNC machines and 5 axis CNC machines are useful for creating molds with deep cavities, for creating complex 3D shapes, and for machining on tilted surfaces of a part without compromising precision.

    However, a 5 axis CNC machine has a wider range of applications than 4 axis CNC machines. For example, it has become particularly dominant in producing parts like impellers and turbine blades, which have contoured surfaces unsuitable for 3-axis machining and 4 axis machining.

    Conclusion

    4 axis CNC machines and 5 axis CNC machines are common CNC machining moiety you must have heard while running a project. Generally, there are three common axes in CNC machining (3 axis, 4 axis, and 5 axis). However there are other types (3+2 axis CNC machining and simultaneous 5 axis machining).  In order to understand CNC machining axes, this article introduce their principles, types, and benefits. By going through this article, you will have an idea of 4 axis and 5 axis CNC machining.

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