Modern CNC machines can produce prototypes and custom production parts very quickly and accurately. They must be able to move along multiple axes while still maintaining dimensional accuracy.
CNC machining can be classified by the number and type of axes they use. The most common is 3-, 4-, or 5-axis, also known as multi-axis machining. These movements affect the production efficiency and accuracy, as well as the parts that can be made. The more freedom you have, the more complicated the geometries can be made. If you are planning to produce CNC machined parts or prototypes, you should understand what’s the different between them as that can help you to make a smarter decision.
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How Does a CNC Machine Move?
When we are talking about the movement, surely we are not referring to the machine lifting itself up and running away. We are referring to the relative movement of the cutting instrument that cut the workpiece.
How do we identify which axis it is? Imagine you are facing a 3-axis CNC mill. The X axis, which is parallel to your reference point, will move left to right from the front of your body. The direction perpendicular is the forward and back directions of the Y axis, while the Z is vertical.
The worktable in a typical mill moves on the Z/Y plane. The Z axis is the movement of the spindle which holds the cutting instrument. The spindle holds the cutting tool, and rotates around the Z axis. However, this rotational motion is not considered an “axis of motion”.
These motions together create a three-dimensional space that is a cubic volume in which the machine performs cutting operations.
What is a 3-Axis Machining Used For?
For a variety milling operations, we use 3-axis machines daily. They are great for quick and efficient material removal as well as making flat and planar surfaces. These geometrical shapes, which are essentially rectilinear in nature, are known as prismatic. A 3-axis mill is capable of making rounded profiles, but it’s not the best tool for this job.
Three-axis mills can be used to drill or tap holes. However, they are limited to drilling along the Z-axis. Because the spindle cannot move up and down, it can’t enter the workpiece from either side. This limitation is for parts that require holes or pockets to be machined on multiple faces. The 3-axis machine can’t normally do this.
This limitation can be overcome by removing the part from the worktable and repositioning it. If there is no alternative, this can be done. However, the workpiece must then be re-indexed. This means that touch probes are used to establish a new point of reference before the machine can be restarted.
This can be a slow process that could lead to dimensional errors. It is best to avoid taking a part from its fixture and moving it halfway through a job.
A 3-axis mill is capable of making circular features, but only on the X/Y plan. However, it’s fine for projects that don’t require complexity. They also benefit from maximum throughput and process efficiency.
What Are the Advantages of a 4-Axis CNC Machining
The addition of a fourth axis of motion can open up new possibilities for machining. This is often done by adding rotary motion to the X-axis. This is known as the A axis.
The rotary table allows the machinist to mount a part on one side and rotate it to access other sides. This eliminates the need to remount and reindex as with a 3-axis mill. Parts are partially suspended, meaning they don’t touch the surface of the worktable. This makes it possible to drill holes and other features that penetrate through the part.
The most important thing is that the workpiece can be rotated while being machined, allowing for more complicated curves and contours. You can turn a part as if it were on a lathe to create cylindrical or spherical profiles. The 4-axis mill is not designed for this kind of operation, so it will take longer than if you use a dedicated lathe.
What Are the Benefits of a 5-Axis CNC Machining
With 5-axis CNC milling, another degree of freedom is available, this time along Y-axis. Rotation around Y can be called the B-axis.
A 3-axis mill can be retrofitted to have a trammel head. This will allow for five axes freedom. This attachment provides motion on both the A and B axes. Combining the capabilities of a 3-axis machine, it is now possible to create more complex shapes like helical rotors. These complex compound curves can be made in multiple directions on a 5-axis machine.
A 3-axis machine equipped with a trammel head has its limitations. A dedicated 5-axis machine, on the other hand, is more rigid. It must maintain accuracy while simultaneously moving in multiple directions. Even for parts that are relatively simple, this precision allows for tighter tolerances.
What Are the Other Axes?
CNC machining centers have been greatly expanded in order to produce more complex parts faster and with fewer setups. The 9-axis machine combines lathe, milling and advanced robotics functions to offer all-in-one solutions. These machines are often large and difficult to use. These machines are often used in aerospace, military and scientific applications.
Most products require 5 axes CNC machining to produce feature-rich parts with tight tolerances. Want.Net can build prototype or custom machined parts for you at a affordable price. Contact us to get a quick quote today.
