3, 4, 5 axis CNC machining process difference?
We use many modern 3-axis, 4-axis and 5-axis cnc machining centers to produce excellent CNC parts. Milling technology has been widely used in various applications in CNC precision machining. For example, industries such as aerospace, optics, and medical rely on milling to manufacture precision parts.
Customers need to understand the various types of CNC milling machines available to optimize their use. The main difference is the axis on which the machine runs. These movements provide CNC milling machines with the freedom to produce complex geometries. In short, the more axes, the wider the range of functions. The number of axes also affects the accuracy and efficiency of the machine.
How does the CNC milling process move?
Before understanding the different types of CNC milling machines, you need to understand the axis. The X axis is parallel to the front of your body, moving left and right. The Y axis is perpendicular to you, moving back and forth. Finally, the Z axis is in a vertical position that moves up and down. The other rotation axis depends on the rotation of the X, Y or Z axis. This will create the A, B, and C axes.
A typical table milling machine moves along the X/Y plane. The spindle holding the tool moves on the Z axis. Therefore, this range of motion defines the 3D space in which the mill works. The following is a further understanding of the main differences between different CNC milling machines.
What is three-axis machining?
Three-axis milling machines use three axes, namely X, Y and Z axes. When a 3-axis machine tool moves the tool along the 3-axis, the workpiece remains fixed. At Creatingway, we use 3-axis machines to manufacture 2D and 2.5D geometric parts. We can even process all 6 sides of the part. However, this process requires additional fixtures to achieve.
The 3-axis machine also allows room for the design of certain tilting features. These features must be angled to an X, Y, or Z axis.
What are the advantages of three-axis machining?
The 3-axis CNC machining process has the ability to perform multiple milling operations. We advocate using them because these machines can remove material from the workpiece quickly and efficiently. The resulting surface is usually flat or flat. Unlike organic circles, the singular name for this type of geometric shape is prismatic.
We use a 3-axis milling machine to drill and tap the workpiece. However, this can only be done along the Z axis. The reason is that the spindle can only move up and down and cannot pass through the side of the workpiece. Therefore, this limits the machining of parts that require grooves and holes on multiple faces. The machine cannot access all faces at all.
Fortunately, one way to overcome this limitation is to unload the workpiece and reposition it on the workbench. We try to avoid using this option as it may cause inaccurate dimensions if it is not repositioned correctly. One way to reduce the error is to use the probe to obtain a new reference point of the workpiece. Although this step slows down the entire process, you can be sure that the possibility of error is low.
What is the four-axis CNC machining process?
In addition to the additional rotary axis, the 4-axis milling machine still uses the aforementioned linear 3-axis. The A-axis rotates the workpiece, thereby expanding the capabilities of the 4-axis machine tool. The typical layout of a 4-axis machine tool is that the spindle is in a vertical position relative to the workpiece. Then, the workpiece is mounted on the X axis and rotated together with the fixture on the A axis. This position allows us to machine all 4 sides of the part in one fixture.
Common 4-axis CNC machining process types include: continuous and indexing.
Continuous 4-axis machining involves cutting material from the workpiece while the workpiece is rotating on the A axis. This allows the creation of complex contours such as spirals and cam lobes.
Index 4-axis machining involves the rotation of the workpiece around the a-axis, and the machine does not cut the material. Once we have the required rotation, we apply the brakes to the workpiece.
What are the advantages of 4-axis machining?
Adding the 4th axis of the workpiece movement adds more processing possibilities. We can easily access all sides of the workpiece without disassembly and repositioning. This advantage translates into cost reduction, because additional fixtures can be added to achieve repositioning.
The risk of human error has also become lower. Therefore, you may get the highest quality parts. Eliminating the loss of accuracy seen in 3-axis machining did not result in tighter tolerances. In addition, since the workpiece is partially suspended, the drill holes and features penetrate as completely as possible.
An additional benefit is the ability to machine inclined features that cannot be achieved with 3-axis CNC machining. However, all features to be machined must be angled around similar axes. Otherwise, the process will require additional fixtures to machine features of different axes.
What is five-axis machining?
The 5-axis milling machine uses all 4 axes and an additional rotation axis. This type of CNC milling machine utilizes 2 of the 3 possible rotation axes. Therefore, the machine either uses the rotation of the C-axis and the A-axis, or the rotation of the C-axis and the B-axis. This rotation occurs on the spindle or workpiece.
The B axis is the rotation around the Y axis in the XYZ plane. We can achieve this extra movement by attaching a trammel head. This modification allows complex shapes to be created in almost any direction. For example, spiral rotors are notorious for having complex curves in multiple directions. A 5-axis CNC machine tool can easily produce this part.
Common types of 5-axis CNC machine tools include full-continuous 5-axis machine tools and 3+2 machine tools.
A fully continuous 5-axis machine can produce very complex 3D shapes. The reason is that it allows two rotating shafts to rotate at the same time. This function ranges from complex curved 3D surfaces to flat compound angle features. As a result, we can even produce parts that are usually manufactured only through the molding process.
On the other hand, 3+2 axis machine tools only allow independent operation of the rotary axis. Therefore, we cannot rotate two rotation axes at the same time. However, this type can make very complex 3D shapes.
What are the advantages of 5-axis machining?
Due to the shortened delivery time, most customers prefer 5-axis. The 5-axis CNC machining process is famous for its single-step machining process, which can better contact the geometry of the part. In addition, the service life of these tools is significantly extended due to better cutting positioning on the workbench.
Which one to choose, 3, 4 or 5 axis machining?
Although five-axis machine tools have all the advantages, not all products are suitable for it. For example, a 5-axis machine is rigid. Therefore, even for simple parts, we can still achieve high tolerances. This may translate into higher costs. Why not consider 3-axis machining that can still complete the job at a much lower cost.
