Which command is used to turn off the coolant in CNC machining?

The command that is used to turn off the coolant in CNC machining is M9. In CNC programming, M codes are typically designated for miscellaneous functions, which include commands related to machine operation.

M9 specifically instructs the CNC machine to deactivate the coolant system, ensuring that no coolant is applied during the machining process. This might be necessary in specific situations, such as when switching to a different operation that does not require coolant or needing to avoid contamination.

In the context of the other options, while G41 is used for tool compensation, M5 is used to stop the spindle, and G83 is a command for a canned drilling cycle. None of these commands serve the function of controlling the coolant, which makes M9 the correct answer for turning off the coolant in CNC machining.