Miscellaneous Functions, M

The miscellaneous functions or M-codes are the ones used for operating the machine tool functions. Generally, only one-M code is supposed to be given in a single block.

Similar to G-codes, ISO has standardized a number of M-codes as follows :

Code               Function

M00                 Program stop, spindle and coolant off

M01                 Optional programmable stop

M02                 End of program - often interchangeable with M30

M03                 Spindle on, CW M04  Spindle on, CCW

M05                 Spindle stop

M06                 Tool change

M07                 Coolant supply No. 1 on

M08                 Coolant supply No. 2 on

M09                 Coolant off

M10                 Clamp

M11                 Unclamp

M12                 Unassigned

M13                 Spindle on, CW (+) coolant on

M14                 Spindle on, CCW (-) coolant on

M15                 Rapid traverse in + direction

M16                 Rapid traverse in - direction

M17-M18        Unassigned

M19                 Spindle stop at specified angular position

M20-M29        Unassigned

M30                 Program stop at end tape + tape rewind

M31                  Interlock by-pass

M32-M35        Constant cutting velocity

M36-M39        Unassigned

M40-M45        Gear changes; otherwise unassigned

M46-M49        Unassigned

M50                 Coolant supply No. 3 on

M51                 Coolant supply No. 4 on

M52-M54        Unassigned

M55                 Linear cutter offset No. 1 shift

M56                 Linear cutter offset No. 2 shift

M57-M59        Unassigned

M60                 Piece part change

M61                 Linear piece part shift, location 1

M62                 Linear piece part shift, location 2

M63-M67        Unassigned

M68                 Clamp piece part

M69                 Unclamp piece part

M70                 Unassigned

M71                 Angular piece part shift, location 1

M72                 Angular piece part shift, location 2

M73-M77        Unassigned

M78                Clamp non-activated machine bed-ways

M79                 Unclamp non-activated machine bed-ways

M80-M99        Unassigned

In the following a few of the M-codes that are generally found in most of the controllers are described. The other M-codes should be checked in conjunction with the programming manual of the machine tool.

M00     Program stop or Pause. This would stop the machine after completing the instructions in the block. To continue further, the operator will press the 'Start' button on the control panel. This is generally useful for altering the clamp position or inspection.

M01     This is similar to above and is termed 'Optional stop'. This will stop like M00 when the "Optional stop" switch on the controller is 'ON'. This is normally used for random inspection.

M02     This is logical 'End of program'.

M03     This is the function to start the machine spindle in the clockwise direction. When it is given in a block would be the first code to be executed before all the other codes in a block are acted upon.

M04     This is the function to start the machine spindle in the counter clockwise direction. When it is given in a block would be the first code to be executed before all the other codes in a block are acted upon.

M05     This is used to stop the machine spindle. When it is given in a block would be the last code to be executed after all the other codes in a block are acted upon.

M06     is for tool change.

 M07    is for 'Coolant 1 On'.

 M08    is for 'Coolant 2 On'.

 M09    is for 'Coolant Off'.

M30     This is also the 'End of program' and is called 'Rewind'.

Program Number

Generally, it is necessary to specify an identification for each of the program in terms of a program number. The symbol used for the program number in Fanuc controls is "O" or ":", followed by its number. For example, O238 or: 238. The programs are generally stored in the CNC controller memory using the program number.