A 4-axis CNC machine is controlled using a computer program and a controller. The controller interprets the program and sends commands to the machine to move the cutting tool in the X, Y, Z, and A (rotational) axes.

Here is a general overview of the process:

1. Design the part or object you want to create using computer-aided design (CAD) software.
2. Convert the design into a machine-readable language using computer-aided manufacturing (CAM) software.
3. Load the CAM program onto the controller, either through a wired or wireless connection.
4. Mount the material to be cut onto the machine’s worktable.
5. Turn on the machine and initialize the controller.
6. The controller reads the program and sends commands to the machine to move the cutting tool in the X, Y, Z, and A axes to create the part.
7. Once the machining process is complete, the part is removed from the machine and inspected for quality.

The controller and the CNC machine work together to accurately move the cutting tool along the specified path to produce the desired shape and dimensions of the part. The operator can also monitor the machining process, pause or stop it if necessary, and make adjustments to the program or machine as needed.