M-code, or miscellaneous function codes, are essential commands used in CNC (Computer Numerical Control) machines to control various auxiliary functions beyond the primary machining operations. These codes play a crucial role in automating processes, enhancing precision, and ensuring the smooth operation of the machine. From controlling the spindle and coolant systems to managing tool changes and coordinate systems, M-codes provide a standardized way to execute a wide range of machine functions.
M-Code for Milling
An list of all the possible M-codes for a specific milling machine would depend on the make and model of the machine. However, here are some common M-codes that are used on many milling machines:
| M00 | Program stop |
| M01 | Optional program stop |
| M02 | End of program |
| M03 | Spindle on clockwise |
| M04 | Spindle on counterclockwise |
| M05 | Spindle stop |
| M06 | Tool change |
| M07 | Cooling (air cooling) on |
| M08 | Coolant on |
| M09 | Coolant off |
| M13 | 4th axls clamp |
| M14 | 4th axls unclamp |
| M15 | 5th axls clamp |
| M16 | 5th axls unclamp |
| M30 | End of program with rewind |
| M41 | Gear selection (cutting speed) |
| M48 | Enable overrides |
| M49 | Disable overrides |
| M98 | Subprogram call |
| M99 | Subprogram end |
| M19 | Orient spindle for angle measurement |
| M20 | Return spindle to normal position |
| M21 | Left-hand coordinate system |
| M22 | Right-hand coordinate system |
| M24 | Automatic tool changer start |
| M25 | Automatic tool changer stop |
| M26 | Automatic tool changer unclamp |
| M27 | Automatic tool changer clamp |
| M28 | Automatic pallet changer start |
| M29 | Automatic pallet changer stop |
| M30 | Automatic pallet changer unclamp |
| M31 | Automatic pallet changer clamp |
| M48 | Allow feed and rapid override |
| M49 | Prohibit feed and rapid override |
| M50 | Exact stop check on |
| M51 | Exact stop check off |
| M52 | Spindle speed override on |
| M53 | Spindle speed override off |
| M54 | Feed override on |
| M55 | Feed override off |
| M56 | Rapid override on |
| M57 | Rapid override off |
M-code for Turning
The following table is a fairly comprehensive reference listing of the most typical and common M-codes (miscellaneous functions) used for CNC turning (CNC lathes). Only a very few M-codes are industry standard and common to all controls.
| M-code | Description |
|---|---|
| M00 | Mandatory program stop |
| M01 | Optional program stop |
| M02 | End of program (usually no reset and rewind) |
| M03 | Spindle rotation normal – clockwise |
| M04 | Spindle rotation reverse – counterclockwise |
| M05 | Spindle rotation stop |
| M07 | Coolant mist ON |
| M08 | Coolant pump motor ON |
| M09 | Coolant pump motor ON |
| M10 | Chuck or collet open |
| M11 | Chuck or collet close |
| M12 | Tailstock quill IN |
| M13 | Tailstock quill OUT |
| M17 | Turret indexing forward |
| M18 | Turret indexing reverse |
| M19 | Programmable spindle orientation |
| M21 | Tailstock body forward |
| M22 | Tailstock body reverse |
| M23 | Gradual pull-off from thread ON |
| M24 | Gradual pull-off from thread OFF |
| M30 | End of program with reset and rewind |
| M41 | Gear range selection – low gear |
| M42 | Gear range selection – medium gear 1 |
| M43 | Gear range selection – medium gear 2 |
| M44 | Gear range selection – high gear |
| M48 | Feedrate override cancel OFF – feedrate override switch effective |
| M49 | Feedrate override cancel ON – feedrate override switch ineffective |
| M98 | Subprogram call |
| M99 | Subprogram end or Macro end |
It’s important to note that this is not a definitive list, and the codes that are available to you may vary depending on the specific machine you’re using. It’s always recommended to consult the machine’s manual for a complete list of codes and their usage.
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