{"id":6303,"date":"2026-05-21T03:12:50","date_gmt":"2026-05-21T03:12:50","guid":{"rendered":"https:\/\/nylonplastic.com\/what-is-g-code-cnc-programming-guide\/"},"modified":"2026-05-21T06:38:32","modified_gmt":"2026-05-21T06:38:32","slug":"what-is-g-code-cnc-programming-guide","status":"publish","type":"post","link":"https:\/\/nylonplastic.com\/ko\/what-is-g-code-cnc-programming-guide\/","title":{"rendered":"What Is G-Code? Understanding CNC Programming Fundamentals"},"content":{"rendered":"
\"CNC
G-code programming interface showing toolpath commands and machine instructions<\/figcaption><\/figure>\n

G-code (Geometric code) is the fundamental programming language that controls Computer Numerical Control (CNC) machines. Every movement, speed change, tool change, and auxiliary function executed by a CNC mill, lathe, router, or EDM machine is ultimately driven by G-code instructions. Understanding G-code is essential for manufacturing engineers, CNC programmers, and anyone involved in precision machining operations.<\/p>\n

What Is G-Code?<\/h2>\n

G-code is a numerical control programming language standardized under ISO 6983 and RS-274. It uses letter-address codes \u2014 “G” commands for geometry (motion), “M” commands for miscellaneous machine functions, and letter prefixes for parameters such as feed rate (F), spindle speed (S), and tool number (T).<\/p>\n

A typical G-code block looks like this:<\/p>\n

G01 X10.500 Y5.250 F50.0 ; Linear interpolation at 50 ipm feed rate<\/p>\n

G-Code Command Categories<\/h2>\n

G-Codes (Motion and Geometry)<\/h3>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Command<\/th>\nFunction<\/th>\n<\/tr>\n<\/thead>\n
G00<\/td>\nRapid positioning (non-cutting move)<\/td>\n<\/tr>\n
G01<\/td>\nLinear interpolation (straight-line cutting)<\/td>\n<\/tr>\n
G02 \/ G03<\/td>\nCircular interpolation (clockwise \/ counterclockwise)<\/td>\n<\/tr>\n
G17 \/ G18 \/ G19<\/td>\nPlane selection (XY \/ ZX \/ YZ)<\/td>\n<\/tr>\n
G20 \/ G21<\/td>\nUnits (inches \/ millimeters)<\/td>\n<\/tr>\n
G40 \/ G41 \/ G42<\/td>\nCutter compensation (off \/ left \/ right)<\/td>\n<\/tr>\n
G43 \/ G49<\/td>\nTool length offset (on \/ off)<\/td>\n<\/tr>\n
G54-G59<\/td>\nWork coordinate systems (WCS)<\/td>\n<\/tr>\n
G80-G89<\/td>\nCanned cycles (drilling, boring, tapping)<\/td>\n<\/tr>\n
G90 \/ G91<\/td>\nDistance mode (absolute \/ incremental)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

M-Codes (Machine Auxiliary Functions)<\/h3>\n\n\n\n\n\n\n\n\n\n
Command<\/th>\nFunction<\/th>\n<\/tr>\n<\/thead>\n
M00<\/td>\nProgram stop (operator intervention required)<\/td>\n<\/tr>\n
M03 \/ M05<\/td>\nSpindle on (CW) \/ Spindle stop<\/td>\n<\/tr>\n
M06<\/td>\nTool change<\/td>\n<\/tr>\n
M08 \/ M09<\/td>\nCoolant on \/ Coolant off<\/td>\n<\/tr>\n
M30<\/td>\nProgram end and rewind<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\"G-code
G-code program listing showing G01 linear interpolation and M03 spindle commands<\/figcaption><\/figure>\n

From CAD to G-Code: The CAM Workflow<\/h2>\n

CNC operators rarely write G-code manually for production parts. Instead, the workflow follows:<\/p>\n

    \n
  1. CAD Modeling<\/strong>: Engineer creates 3D model with geometric dimensions and tolerances<\/li>\n
  2. CAM Programming<\/strong>: CAM software (Mastercam, Fusion 360, SolidWorks CAM) imports the CAD model and generates toolpaths<\/li>\n
  3. \ud3ec\uc2a4\ud2b8 \ud504\ub85c\uc138\uc2f1<\/strong>: The CAM post-processor translates generic toolpaths into machine-specific G-code syntax<\/li>\n
  4. Verification<\/strong>: G-code simulation detects collisions, over-travel, and cycle time issues<\/li>\n
  5. Machine Execution<\/strong>: G-code is loaded to the CNC controller and executed<\/li>\n<\/ol>\n

    Absolute vs. Incremental Programming<\/h2>\n

    G-code supports two distance modes:<\/p>\n