5-axis CNC machining or multi-axis machining is a very versatile machining process that adds two degrees of freedom to a CNC mill or CNC lathe. In addition to the three linear axes of motion, the additional two degrees of freedom come from the ability to rotate the workpiece, the tool head, or both. This introduces A, B, C axes that rotate around X, Y, Z respectively.
The extra degrees of freedom allow for greater tool accessibility, enabling the machining of more complex geometries. There is an added benefit of single-setup machining, sometimes referred to as “one-piece machining,” which increases efficiency by reducing machining time.
There are three main types of multi-axis CNC machines: 5-axis indexing CNC milling, 5-axis continuous CNC milling, and 5-axis milling/turning centers.
What is 5-axis indexing CNC milling?
5-axis indexed milling or 3+2 machining works by rotating the workpiece around the B and C axes to the desired position. The workpiece then remains stationary while the tool makes the desired cut around its three linear axes. When changing the cut position, the B and C axes will reposition the workpiece and then remain stationary again at that cut position. This machining method is also known as 3+2 CNC milling because the extra two degrees of freedom do not work simultaneously with the three linear axes of the tool.
The main advantage of this method is that there is no need to manually reposition the workpiece. This reduces manufacturing time and increases the accuracy of parts with complex geometries compared to using 3-axis milling.
✅ No need to manually reposition the workpiece
✅ Reduced manufacturing time compared to 3-axis CNC machining
❌ Inability to cleanly machine contoured surfaces
❌ Increased cost compared to 3-axis CNC machining
What is 5-axis continuous CNC milling?
A 5-axis continuous CNC milling machine is similar to a 5-axis indexing CNC milling machine, but the workpiece can be continuously rotated around the B and C axes during machining.Between them, the workpiece and tool can be moved along five different axes simultaneously, enabling the machining of complex features. Smooth contoured surfaces, such as those on turbine blades, can be produced with very high precision, making this method popular in the aerospace industry. Expensive machinery and the need for advanced mechanics greatly increase the cost of this method.
✅ Ability to machine complex features and smooth surfaces in one setup
✅ Produce complex parts with precision unattainable by any other process
❌ The most expensive CNC machining method
❌ Some tool limitations still apply
What is a Mill Turn Center?
The milling-turning center is called a milling-turning machine, which, as the name suggests, is a combination of a CNC milling machine and a CNC lathe. The workpiece can be rotated on a rotary axis at high speed for CNC turning operations, and then rotated and held at precise angles for CNC milling operations.Mill-turn machines offer manufacturers the combination of the productivity-enhancing productivity of CNC turning and the design flexibility of CNC milling. These versatile CNC machines are ideal for parts that require multiple machining operations. Machining in one complete cycle can speed up part production and improve accuracy as no additional setup is required. Due to the increased efficiency of CNC turning, parts can be produced at a much lower cost than other 5-axis machines.
✅ Lower cost compared to other 5-axis machining processes
✅ Single setup and turning for high volume production
❌ Limited tool access creates design constraints compared to 5-axis
CNC machining summary
If your parts have relatively simple geometries, 3-axis CNC milling is the best choice as it provides excellent accuracy at a low cost.
CNC turning is ideal for rotationally symmetric parts, it can provide tight tolerances and a lower unit cost.
5-axis indexing CNC machining is suitable for more complex parts; since only one setup is required, higher part accuracy and production speed can be achieved.