What does the M-code in CNC programming typically denote?

The M-code in CNC programming refers specifically to miscellaneous functions that control various operations of the machine, such as tool changes, spindle control, coolant activation, and other auxiliary functions. These are essential in managing the machine's operations during the machining process.

While G-codes typically provide movement instructions, M-codes facilitate actions that don't involve direct motion, allowing for a more efficient and controlled machining environment. This includes operations like starting and stopping the spindle, activating coolant systems, and other non-motion related commands that ensure the machining process runs smoothly. Therefore, M-codes are a critical component in CNC programming, as they outline instructions necessary for the overall machining job beyond just the movement of the tool or workpiece.