What are G codes typically referred to as in CNC programming?

G codes are generally referred to as preparatory commands in CNC programming because they set up the machine to perform specific tasks or functions. These codes dictate the motion of the machine, including movements along axes, and can define operations like circular interpolation, dwell, or coordinate system shifts. The primary purpose of G codes is to prepare the CNC machine for the desired machining operation, thus the term "preparatory" accurately reflects their role in establishing conditions needed for specific tasks.

In the context of CNC programming, these codes are essential for guiding the machining process, which is why they bear this specific designation. Each G code indicates a different action or operation, providing the machine with precise instructions to follow during the machining cycle, which is a fundamental aspect of efficient and accurate CNC operation.