What is the specific purpose of the M06 code in a CNC program, and what machine action does it initiate?

The specific purpose of the M06 code in a CNC program is to initiate a tool change. The M06 code, which stands for "Miscellaneous function 06", signals to the CNC machine's control system that the current cutting tool needs to be replaced with a different tool. The M06 command typically requires an associated T-code (e.g., T01, T02) to specify which tool should be loaded into the spindle. The T-code identifies the tool number that corresponds to a specific tool stored in the machine's tool magazine or carousel. When the CNC control encounters the M06 T01 command, the machine will execute a sequence of actions to perform the tool change. This sequence usually involves: retracting the current tool from the workpiece, stopping the spindle, moving the machine axes to a designated tool change position, activating the automatic tool changer (ATC) mechanism to remove the current tool from the spindle and insert the specified tool (T01) from the magazine, and then returning the machine axes to the machining position, ready for the next operation. After the tool change is complete, the CNC program continues execution with the newly loaded tool. The precise movements and actions involved in the tool change sequence are determined by the machine's specific parameters and the configuration of its ATC system. For example, a program might contain M06 T03 to change to a 3/8" end mill stored as tool #3.