The G stands for “Grammatical,” a reference to the use of words to represent actions. This coding language is used to precisely control the movements of a machine tool along multiple axes. While G-Code can be created using software, it’s typically written on a CAD/CAM (Computer-Aided Design and Computer-Aided Manufacturing) system. The CAM uses the information from the CAD program to create an axis tool path.
What’s in a G-Code?
G-Code is created using coordinate geometry. The X, Y, and Z represent the axis of the machine’s movement. A fourth designation, W, is used to designate work coordinates not tied to any particular machine axis. G-Code files are saved in ASCII format with the exception of certain CAM-specific extensions which are used for special functions. A G-Code file contains the following basic information:
- G-Codes (commands)
- Numeric-operation codes
- Letter operation codes
Common G-Codes
The code is created using certain commands which are used to define feeds, speeds, paths, machine positioning, and tool movements. Commonly used G codes include:
- G0 – Rapid Motion
- G1 – Linear Interpolation (traverse)
- G2, G3 – Circle
- G28, G29 – Home Positioning
- G90, G91 – Absolute or Incremental Motion (coordinate-wise)
- M (M code) – Machine Parameters such as tool selection, units, and planes (X/Y)
- T (T code) – Select Tool
- F (F code) – Feedrate Commands
- S (S code) – Spindle Speed Command
- W (W code) – Work Offset Commands
- Z-Plane Selection Commands
As you work with G-code in CNC projects, it is vital that you understand what the code represents in real life. For example, if someone has to cut parts on their machine (tool) they should know how fast they move (feed rate), the specific tool used (spindle speed), and where they start cutting (work offsets).
What Do You Use G-Code For?
G-code is a programming language that allows machines to execute instructions. It’s an acronym for “Graphics And Code”. This programming language has been developed by the manufacturing industry to provide flexibility in toolpath creation and control of the machine itself.
It can easily be programmed to create toolpaths for specific tools and machining processes. When a G-Code program is loaded onto a CNC machine, it gives the machine precise instructions on how to move and cut through materials in order to produce the desired component.
Three Categories of G-Code
G-code is broken up into three broad categories: motion, commands, and circular interpolation. These codes are executed by the machine as it cuts through materials. The code sends signals to stepper motors on the machine so that it can move in a smooth and controlled manner. G-Code was first used extensively in programming milling machines. It can easily be programmed to create toolpaths for specific tools and machining processes. When a G-Code program is loaded onto a CNC machine, it gives the machine precise instructions on how to move and cut through materials in order to produce the desired component.
Benefits of G-Code
G-Code is a skill that needs to be learned, however, once mastered can revolutionize the way CNC machining is done. Some benefits of G-Code programming include, but are not limited to, increasing speed by creating timesaving toolpaths; allowing for use of specialized tools to reach tight spaces; dramatically reducing waste, due to using fewer materials; and reducing labor costs through increased efficiency.
The benefits of G-Code programming are far-reaching and, when used properly, can revolutionize the way CNC machining is done. Companies that have not yet begun G-Code programming are behind the curve and at risk of being left in the dust. The time and resources saved make G-Code programming a no-brainer when compared with the traditional method of manual programming.