G-Code and M-Code: The Secret Languages ​​That Power CNC Machines 💻

  1. G-Code (Geometrical Code) – Motion Control Commands

G-Code is primarily used to define the position and trajectory of a cutting tool (geometry and motion). These commands control where, how, and at what speed the various machine axes (X, Y, Z, etc.) move.

Typical G-Code:

• G00

Command:

• Rapid Traverse

Function:

• Rapid traverse to a specified location without cutting. (Used for moving the blank position)

General G-Code:

• G01

Command:

• Linear Interpolation

Function:

• Linear movement with a specified feed rate (used for machining the workpiece)

General G-Code:

• G02

Command:

• Circular Interpolation (CW)

Function:

• Clockwise circular movement

General G-Code:

• G03

Command:

• Circular Interpolation (CCW)

Function:

• Counterclockwise circular movement

General G-Code:

• G20/G21

Command:

• Inch/Metric Select

Function:

• Set units of measurement (inches or millimeters)

General G-Code:

• G90/G91

Command:

• Absolute/Incremental Positioning

Function :

• Determines the coordinate system for movement.

2. M-Code (Miscellaneous Code) – Additional Function Control Command ✨

M-Code is a command used to control additional functions or mechanical functions of a machine that are not directly related to movement, but rather control the overall operation (Machine Function).

Common M-Code:

• M03

Command:

• Spindle ON (CW)

Function:

• Commands the spindle to rotate clockwise. (Start Cutting)

General M-Code:

• M05

Command:

• Spindle OFF

Function:

• Stops the spindle

General M-Code:

• M08

Command:

• Coolant ON

Function:

• Turn on the coolant system

General M-Code:

• M09

Command:

• Coolant OFF

Function:

• Turn off the coolant system

General M-Code:

• M06

Command:

• Tool Change

Function:

• Automatic tool change

General M-Code:

• M30

Command:

• Program End & Reset

Function:

• Ends the program execution and resets the machine to the start point

3. Relationship and Interoperability

• G-Code and M-Code are used together in each "block" or line of the CNC program.

• G-Code commands the tool to the desired position while M-Code controls various machine functions simultaneously to complete the machining process, such as: N10, G01, X50.0, Y20.0, F100.0, M03, M08;

• N10: Block number (line sequence)

• G01: Move in a straight line

• X50.0, Y20.0: Go to coordinates X=50.0, Y=20.0

• F100.0: Feed rate equal to 100

• M03: Turn on the spindle

• M08: Turn on the coolant

• Understanding both G-Code and M-Code is an essential skill for CNC programmers and machinists, enabling them to read, write, and modify programs efficiently and accurately.

Principles:

• G-Code, M-Code, CNC Language, CNC Programming

Functions:

• Motion Control Commands, Function Control Commands, Machining

Technology:

• CAM, Computer-Aided Manufacturing, Machine Code

Learning:

• CNC Basics, CNC Machining, Programming

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Here is the first image, introducing G-Code as commands for geometry and motion:

And here is the second image, focusing on M-Code as commands for miscellaneous functions: