Preface
5-axis CNC machining is an extremely versatile machining process that employs subtractive machining techniques. The workpiece is cut into the final part by using a cutting tool that works on 5 axes. CNC machining is very popular due to high precision, high efficiency, and repeatability.
The process begins with the use of raw computer-aided design (CAD) files to help program the cutting toolpaths, which are managed by computer numerical control (CNC). Once these tool parts are programmed into a language that the CNC machining machine understands, the process can be fully automated.
This article focuses on the characteristics of 5-axis CNC machining and why it is different from 3-axis or 2-axis machining, as well as the benefits of using a 5-axis CNC machining machine.
Due to the greater number of axes, 5-axis CNC machining milling machines have greater capabilities than 3-axis and 2-axis milling machines. The machine is configured in such a way that it reduces the need for continuous monitoring. The efficiency of manufacturing parts and a single setup are the main reasons why industry chooses to implement 5-axis machining.
How Does 5-Axis CNC Machining Work?
In CNC machining, parts are formed by using cutting tools and subtractive machining techniques, which are cut off on the workpiece to form the desired shape. The shape is predetermined by the original CAD (Computer Aided Design) file. A program is then generated in G-code format that feeds the instructions directly to the CNC machining machine.
At present, CNC machining milling machines most commonly have 3 axes, X, Y and Z. However, 5-axis CNC machining machines use more axes to implement the cutting process from other angles. As a result, axes A, B, and C can be introduced. These axes work with X, Y and Z at rotation angles to provide a 5-axis cutter capable of complex designs while still maintaining a very high quality of the finished product. The A, B, and C axes move in a rotational manner independent of the X, Y, and Z axes. The specific configuration of the machine or CAD design determines which of the 3 additional axes of rotation is used. This 5-axis configuration costs more due to the higher level of calibration and automation required to run CNC machining machines and input commands.
When it comes to precision engineering, 5-axis machining provides the best precision engineering solutions, and it is an industry-leading engineering process in the automotive, aerospace, and medical industries.
5-axis machining configuration
The 3-axis X, Y, and Z work and are calibrated in the same way as a 3-axis CNC machine. The movement of the additional 2 axes working in 5-axis machining is always controlled by a CNC machining program that inputs commands to the machine.
There are basically two types of CNC machining that use 5-axis operation:
Trunnion style
The trunnion type 5-axis machine rotates around the X-axis with the A-axis and the C-axis around the Z-axis. The axis of rotation is represented by the movement of the table. This type is more suitable for larger workloads, as there is no need to compensate for the space occupied by the rotating handle.
Rotation style
When the rotary 5-axis machine is running, the B axis rotates around the Y axis and the C axis rotates around the Z axis. The difference is that the table is always level during the cutting process, which means it can support heavier parts. The axis of rotation is represented by a rotating cutting arm.
What is the cost of CNC 5-axis machining?
The cost depends on the project at hand and the number of parts produced. In addition to the higher cost of purchasing a 5-axis machine, 5-axis CNC machining requires a higher level of setup before you can start producing parts. The higher initial set-up costs during pre-production can result in smaller batches or one-off parts being more expensive compared to equivalent parts produced on a 3-axis CNC machining machine.
This is understandable because 5-axis CNC machining machines are inherently more complex and dynamic than other types of CNC machining machines with fewer axes. 5-axis milling machines are also more time-saving, as they are calibrated to complete the part without any intervention. In general, the workpiece can be completed in a single operation, so downtime is greatly reduced. Reduced fixing requirements, which is especially beneficial for organic, complex parts.
Why are there fewer fixtures for 5-axis CNC machining?
The range of motion achievable with the cutting head and additional axis of rotation means that these machines can reach up to 5 sides of the part. For example, if aerospace requires geometrically complex parts, a 5-axis CNC machine would be the most capable of achieving this due to its ability to reach complex angles and hard-to-reach cutting areas, such as composite curves.
Advantages of 5-axis CNC machining
High-quality finishes
A higher quality finish can be achieved due to the advanced features of the cutting tools that work with 5-axis CNC machining. This is because the tools on a 5-axis CNC machining machine can be shorter. This reduces the vibration of the tool, which reduces "flutter" marks and ensures a smoother surface finish for the final part.
Faster processing
Due to the high speed and increased degree of automation of 5-axis CNC machining, there is little to no intervention or manual process. This is often referred to as "one-piece finish" and "one-time machining". Multi-axis means that the entire workpiece can be cut in one go, rather than requiring multiple operations to complete the final workpiece. This, in turn, leads to faster output capacity.
More complex shapes can be produced
5-axis CNC machining can produce very complex geometries. For example, in the past, machining castings and parts with many different features required a lot of setup to machine and complete the desired shape. However, in most cases, with a single setup, 5-axis CNC machining can be used with just one fixture to complete a workpiece that meets its exact requirements.