Fanuc G Code and M Code List – What Are G Codes and M Codes in CNC

G-code and M-code are essential languages used in CNC programming for the machining process. Here we’ll explain the basics about them and show the list of the Fanuc G Codes and M Codes.

What is G-Code in CNC?

G-Code is a programming language used to control CNC (Computer Numerical Control) machines by giving precise instructions on tool movements. It tells the machine where to move the cutting tool, how fast to move, and what path to follow to shape a part. Each command starts with the letter “G” followed by numbers that represent specific actions, like rapid positioning (G00), linear cutting at a set speed (G01), or circular movements (G02/G03). These codes include coordinates on X, Y, and Z axes to define exact positions, enabling CNC machines to produce complex shapes with high accuracy and repeatability. G-Code is essential for guiding the geometry of the machining process and transforming digital designs into physical parts.

What is M-Code in CNC?

M-Code controls the miscellaneous or auxiliary functions of a CNC machine that are not related to movement. It handles machine operations like starting or stopping the spindle (M03), turning coolant on or off (M08/M09), or changing tools (M06). Each M-Code begins with the letter “M” followed by a number, and these commands ensure the machine performs essential tasks required for the cutting process but unrelated to the tool’s path. M-Codes can vary between machines and are customized to control non-cutting actions that support the machining operation, making them the organizers of machine functions.

How to Understand and Read G Codes

• Identify the letter “G” followed by a number, which gives a movement command.
• Look for coordinate values (X, Y, Z) that specify the tool’s position in space.
• Note the feed rate (F) indicating how fast the tool moves.
• Observe any additional commands that affect motion, like circular interpolation (G02, G03).
• Break down the code line-by-line, recognizing each part’s function in the sequence.

How to Understand and Read M Codes

• Find the letter “M” followed by a number that instructs a machine function.
• Match the code with its meaning, such as spindle start (M03) or coolant on (M08).
• Remember that M codes usually control non-movement operations.
• Check if the M code is combined with others, ensuring commands do not conflict.
• Learn the machine-specific variations to correctly interpret each M code.

Difference Between G Codes and M Codes

G codes and M codes serve different but complementary roles in CNC programming. G-codes focus on controlling the geometry and movement of the cutting tool, directing exactly where and how to cut the material. In contrast, M codes manage the machine’s auxiliary functions that support the cutting process, such as turning the spindle on or off, activating coolant, or changing tools. While G codes command the tool’s path and speed during machining, M codes handle the machine’s operational tasks that are not directly related to tool movement. Together, they enable a CNC machine to work smoothly and efficiently, producing precise parts with coordinated actions.

What Is CNC Programming Language?

CNC programming is the process of writing instructions that tell computer numerical control (CNC) machines how to perform precise manufacturing tasks like cutting, milling, drilling, or shaping materials. These instructions are usually written in a special language called G-code, which acts as the machine’s language, guiding tool movements, spindle speeds, feed rates, and tool changes. CNC programming can be done manually by writing G-code by hand, but nowadays most programmers use CAD (Computer-Aided Design) and CAM (Computer-Aided Manufacturing) software to create 3D models and automatically generate the necessary G-code. This code is organized in blocks, with each block representing a specific step in the machining process, making it easier to read, modify, and troubleshoot. Understanding CNC programming and its language is important for operators and programmers to ensure smooth, accurate, and efficient production.

What Machines Use G-Code?

1. CNC Milling Machines:
CNC milling machines use rotary cutting tools that spin to remove material from a stationary workpiece. These machines can perform many types of milling processes, like face milling or contouring. They use G-code to direct the tool’s path precisely in multiple axes, shaping complex 3D parts.

2. CNC Turning Machines:
Also called CNC lathes, turning machines hold the workpiece and rotate it while a stationary cutting tool shapes the outside surface. G-code controls the tool’s movements, enabling the machine to create symmetrical cylindrical or conical shapes with great precision, commonly used for shafts, bolts, and similar parts.

3. CNC Grinding Machines:
Grinding machines use an abrasive wheel to smooth or finish a surface by removing very small amounts of material. They often work after milling or turning to improve surface quality. G-code guides the grinding wheel’s movements to achieve accurate and smooth finishes.

4. CNC Drilling Machines:
These machines drill holes into a workpiece using a rotating drill bit. G-code programs the drilling locations, depths, and speeds. Drilling CNC machines are often used to create holes for screws, fixtures, or assembly. For larger holes, CNC boring machines are employed.

5. CNC Routing Machines:
CNC routers combine a CNC system with a handheld-style router to cut and carve materials like wood, plastic, or soft metals. They can create detailed patterns or shapes by precisely controlling the router via G-code commands.

6. CNC Laser Cutting Machines:
Laser cutters use a powerful, focused laser beam to melt or vaporize material, cutting it with high precision. G-code directs the laser’s path, but laser cutting is limited to materials that won’t damage the optics, as some plastics release harmful gases when cut.

7. CNC Water Jet Cutting Machines:
Water jet cutters use a fine, high-pressure water stream to cut through materials, including very thick or hard metals. G-code controls the movement of the water jet cutting head, allowing intricate shapes to be cut without heat that could damage the material.

Fanuc G-Code List (Lathe)

G code	Description
G00	Rapid traverse
G01	Linear interpolation
G02	Circular interpolation CW
G03	Circular interpolation CCW
G04	Dwell
G09	Exact stop
G10	Programmable data input
G20	Input in inch
G21	Input in mm
G22	Stored stroke check function on
G23	Stored stroke check function off
G27	Reference position return check
G28	Return to reference position
G32	Thread cutting
G40	Tool nose radius compensation cancel
G41	Tool nose radius compensation left
G42	Tool nose radius compensation right
G70	Finish machining cycle
G71	Turning cycle
G72	Facing cycle
G73	Pattern repeating cycle
G74	Peck drilling cycle
G75	Grooving cycle
G76	Threading cycle
G92	Coordinate system setting or max. spindle speed setting
G94	Feed Per Minute
G95	Feed Per Revolution
G96	Constant surface speed control
G97	Constant surface speed control cancel

Fanuc G-Code List (Mill)

G code	Description
G00	Rapid traverse
G01	Linear interpolation
G02	Circular interpolation CW
G03	Circular interpolation CCW
G04	Dwell
G17	X Y plane selection
G18	Z X plane selection
G19	Y Z plane selection
G28	Return to reference position
G30	2nd, 3rd and 4th reference position return
G40	Cutter compensation cancel
G41	Cutter compensation left
G42	Cutter compensation right
G43	Tool length compensation + direction
G44	Tool length compensation – direction
G49	Tool length compensation cancel
G53	Machine coordinate system selection
G54	Workpiece coordinate system 1 selection
G55	Workpiece coordinate system 2 selection
G56	Workpiece coordinate system 3 selection
G57	Workpiece coordinate system 4 selection
G58	Workpiece coordinate system 5 selection
G59	Workpiece coordinate system 6 selection
G68	Coordinate rotation
G69	Coordinate rotation cancel
G73	Peck drilling cycle
G74	Left-spiral cutting circle
G76	Fine boring cycle
G80	Canned cycle cancel
G81	Drilling cycle, spot boring cycle
G82	Drilling cycle or counter boring cycle
G83	Peck drilling cycle
G84	Tapping cycle
G85	Boring cycle
G86	Boring cycle
G87	Back boring cycle
G88	Boring cycle
G89	Boring cycle
G90	Absolute command
G91	Increment command
G92	Setting for work coordinate system or clamp at maximum spindle speed
G98	Return to initial point in canned cycle
G99	Return to R point in canned cycle

Fanuc M-Code List (Lathe)

M code	Description
M00	Program stop
M01	Optional program stop
M02	End of program
M03	Spindle start forward CW
M04	Spindle start reverse CCW
M05	Spindle stop
M08	Coolant on
M09	Coolant off
M29	Rigid tap mode
M30	End of program reset
M40	Spindle gear at middle
M41	Low Gear Select
M42	High Gear Select
M68	Hydraulic chuck close
M69	Hydraulic chuck open
M78	Tailstock advancing
M79	Tailstock reversing
M94	Mirrorimage cancel
M95	Mirrorimage of X axis
M98	Subprogram call
M99	End of subprogram

Fanuc M-Code List (Mill)

M code	Description
M00	Program stop
M01	Optional program stop
M02	End of program
M03	Spindle start forward CW
M04	Spindle start reverse CCW
M05	Spindle stop
M06	Tool change
M07	Coolant ON – Mist coolant/Coolant thru spindle
M08	Coolant ON – Flood coolant
M09	Coolant OFF
M19	Spindle orientation
M28	Return to origin
M29	Rigid tap
M30	End of program (Reset)
M41	Low gear select
M42	High gear select
M94	Cancel mirrorimage
M95	Mirrorimage of X axis
M96	Mirrorimage of Y axis
M98	Subprogram call
M99	End of subprogram