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The Difference Between 3, 4, and 5-axis CNC Machining Process?

The Difference Between 3, 4, and 5-axis CNC Machining Process?

Have you wondered the difference between 3, 4, and 5-axis machining?

According to LinkedIn:

Milling technology has grown in its use in various applications in CNC precision machining. For instance, industries such as aerospace, optical and medical industries rely on milling to make precise parts.

Clients need to know the various types of CNC mills available so as to optimize their use. The main difference lies in the axes along which the machine operates. These movements provide the CNC milling machine freedom in producing complex geometrics. Simply put, the more the axes the wider the range of capabilities. The number of axes also affects the machine’s accuracy and efficiency.

How Do CNC Mill Machines Process Move?
Before you get to understand the different types of CNC mills, you need to know the axes. The X-axis is parallel to the front of your body, moving in the left to the right direction. The Y-axis is in a perpendicular direction from you, moving back and forth. Lastly, the Z-axis is at a vertical position moving up and down. The other rotational axes depend on the rotation of either the X, Y, or Z-axis. This creates the A, B, and C axis.

A typical worktable mill moves along the X/Y plane. The spindle holding the cutting tool moves on the Z-axis. This range in motion thus defines the 3D space in which the mill works. Here is further insight into the key differences between the different CNC milling machines.

What Is 3-Axis Machining?
A milling machine operating on 3-axis uses three axes, namely the X, Y, and Z-axis. The workpiece remains fixed in place while the 3-axis machine moves the cutting tool along the 3 axes. At Creatingway, we use 3-axis machines to make 2D and 2.5D geometry parts. We can even achieve machining of all 6 sides of your part. However, the process needs an extra fixturing to achieve that.

The 3-axis machine additionally allows room to design certain angled features. These features have to be angled to one X, Y, or Z axes.

What Are the Benefits of 3-Axis Machining?
3-axis CNC machining process has the ability to do several milling operations. We advocate for their use since the machines are fast and efficient in the removal of material from a workpiece. The resulting surfaces are usually either flat or planer surfaces. A singular name for such geometrical shapes is prismatic, unlike organic round shapes…

What Is 4-Axis CNC Machining Process?

The 4-axis milling machine still uses the linear 3 axes mentioned previously, in addition to an extra rotation axis. The A-axis causes rotation on the workpiece thus widening the capabilities of the 4-axis machine. A typical arrangement of a 4-axis machine is where the spindle is in a vertical position relative to the workpiece. Then, the workpiece gets mounted on the X-axis and rotates with the fixture at the A-axis. This position allows us to machine all 4 sides of your part in a single fixture.

The common types of 4-axis CNC machining process include: continuous and indexing.

Continuous 4-axis machining involves cutting material from the workpiece, while it rotates in the A-axis. This allows for the creation of complex profiles such as helixes and cam lobes.

Index 4-axis machining involves rotation of the workpiece about the a-axis, while the machine isn’t cutting material. We apply a brake on the workpiece once we get the desired rotation.

What Are the Benefits of 4-Axis Machining?

The addition of the 4th axis of workpiece motion adds more machining possibilities. We can easily access all the sides of the workpiece without the need for dismounting and repositioning. This advantage translates to lower costs in terms of adding extra fixtures for the reposition to be possible.

The risk of human error also becomes lower. Thus, you are likely to get parts that are of the highest quality. Removal of the loss accuracy seen in 3-axis machining isn’t there resulting in tighter tolerances. Also, due to the partial suspension workpiece, drilling holes and features that penetrate fully as possible.

An extra bonus is the ability to machine angled features that were not possible with the 3-axis CNC machining process. However, all features to be machined must be angled about a similar axis. Otherwise, the process will require additional fixtures to machine features about different axes.

What Is 5-Axis Machining?

A 5-axis milling machine uses all 4 axes with an additional rotation axis. This type of CNC milling machine utilizes 2 out of the possible 3 rotation axis. Thus, the machine either uses a rotation in the C-axis and A-axis, or a rotation in the C-axis and B-axis. This rotation happens on either the spindle or workpiece.

The B-axis is a rotation around the Y-axis in the X-Y-Z plane. We can achieve this extra motion by attaching a trammel head. This modification allows the creation of sophisticated shapes, in virtually any direction. For instance, helical rotors are notorious for having complex curves in multiple directions. A 5-axis CNC machine can easily produce this part.

The common types of 5-axis CNC machines include fully continuous 5-axis machines and 3+2 machines.

A fully continuous 5-axis machine has the ability to produce very complex 3D shapes. The reason is that it allows simultaneous rotation of the two rotation axis. This capability ranges from complex curved 3D surfaces to planar compound angled features. We are thus able to produce even parts normally exclusively made through molding processes.

A 3+2 axis machine on the other hand only allows independent operation of the rotational axes. Thus, we can’t rotate two rotational axes at the same time. However, the type makes great complex 3D shapes.

What Are the Benefits of the 5-Axis Machining?

Most clients prefer the 5-axis due to the resulting reduced lead time. Known for its single-step machining process, 5-axis CNC machining process allows better access to parts in terms of geometry. Also, the tools notably have an extended life due to better cutting positioning on the worktable.

Which to Choose, 3, 4, Or 5-Axis Machining?

Despite a 5-axis machine having all advantages, not all products are suitable for it. For instance, 5-axis machines are rigid. Thus, we still achieve high tolerances even for simple parts. This might translate to higher costs. Why not consider 3-axis machining that can still get the job done at much lower costs…

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