4 Axis CNC Milling Machines
A 4 Axis Mill adds an additional rotary axis. Compared to the 3 axis mill which is a more simple VMC, a 4th axis mill allows rotation on the X-axis. Many brands carry 4 Axis CNC machines like Haas, Laguna, Hardinge and others.
4 Axis CNC Mill Machines
How Does a 4 Axis CNC Mill Compare with 3 and 5 Axis Mills?
A normal CNC milling machine has three axes: the X, Y and Z axis. From the front of a machine, the X-axis is left to right, the Y is front to back and the Z is up and down. The workpiece is stationary on a bed and the cutter does all the moving (unless there is a T-slot bed).
| 3 Axis CNC Mill | 4 Axis CNC Mill | 5 Axis CNC Mill |
|---|---|---|
| This configuration can mill slots, drill holes and face off parts with the cutter in the vertical direction only. | Generally, the 4th axis rotates around the X-axis (which moves left to right). This allows you to make holes and slots in the front and back of the workpiece. The cutter can rotate around the part which is fixed on a table. The fourth axis is called the A axis. | When the A axis is at zero, a fifth axis would be perpendicular to the Z axis. The cutter can be rotated 90 degrees towards to the front of the machine and moved to allow for milling around the sides of the workpiece. The 5th axis is called the C axis. |
The complexity of parts that can be made in one setup increases as the number of axes increase.
Selecting the Best Type of Used 4 axis CNC Mill
When deciding on the type of used 4 axis mills to purchase, key factors to consider will be part complexity, part mix and the average number of parts to be run per setup.
- Part Complexity: Do you want to machine complex parts? Consider the number of tool pockets available - the more stations, the more complexity in one setup.
- Primary Industry: Is your shop dedicated to a single manufacturing field like automotive, aerospace, mold & die, medical device or oil? The different industries have different demands for torque, speed and precision. For example, medical devices frequently require smaller, high-precision parts. Aerospace demands difficult to machine materials and many large parts. This would indicate that you need a 4 axis CNC mill with enough power to handle tough materials.
- Physical Size: You'll want to consider the physical size of your used CNC 4 axis machine. This will be dictated by the size of parts to be machined in diameter, length, X, Y and Z travel, as well as any other axis travel in degrees. Then you'll need to determine the rigidity and horsepower requirements by thinking about the types of materials that you will be machining.
- Built to order: Keep in mind that some multi-axis machines are better than others for particular applications. It is helpful to learn if a particular used CNC machine was used in a similar application before. Often 4 axis CNC machines are built to order per a specific customers needs. When you buy used, you're looking for the closest fit from existing machines.