What Is G-Code?
A typical G-code block looks like this:
G01 X10.500 Y5.250 F50.0 ; Linear interpolation at 50 ipm feed rate
G-Code Command Categories
G-Codes (Motion and Geometry)
| Command | Function |
|---|---|
| G00 | Rapid positioning (non-cutting move) |
| G01 | Linear interpolation (straight-line cutting) |
| G02 / G03 | Circular interpolation (clockwise / counterclockwise) |
| G17 / G18 / G19 | Plane selection (XY / ZX / YZ) |
| G20 / G21 | Units (inches / millimeters) |
| G40 / G41 / G42 | Cutter compensation (off / left / right) |
| G43 / G49 | Tool length offset (on / off) |
| G54-G59 | Work coordinate systems (WCS) |
| G80-G89 | Canned cycles (drilling, boring, tapping) |
| G90 / G91 | Distance mode (absolute / incremental) |
M-Codes (Machine Auxiliary Functions)
| Command | Function |
|---|---|
| M00 | stop (operator intervention required) |
| M03 / M05 | Spindle on (CW) / Spindle stop |
| M06 | Tool change |
| M08 / M09 | Coolant on / Coolant off |
| M30 | end and rewind |
From CAD to G-Code: The CAM Workflow
CNC operators rarely write G-code manually for production parts. Instead, the workflow follows:
- CAD Modeling: Engineer creates 3D model with geometric dimensions and tolerances
- CAM ming: CAM software (Mastercam, Fusion 360, SolidWorks CAM) imports the CAD model and generates s
- 後処理: The CAM post-processor translates generic s into machine-specific G-code syntax
- Verification: G-code simulation detects collisions, over-travel, and cycle time issues
- Machine Execution: G-code is loaded to the CNC controller and executed
Absolute vs. Incremental ming
G-code supports two distance modes:
- Absolute (G90): All coordinates are referenced from the zero (G54 work coordinate system). X10.0 always means “move to X=10.0 in the current WCS.” Safer and more widely used.
- Incremental (G91): Coordinates are relative to the current tool position. X10.0 means “move 10.0 units from where you are.” Used for patterns and repetitive features.
Common G-Code ming Mistakes
- Missing Tool Length Compensation (G43): Causes Z-depth errors and potential crashes
- Incorrect Work Offset (G54 vs G55): Causes parts to be machined in the wrong location
- Rapid Moves (G00) Too Close to Workpiece: Causes tool breakage or part scrap
- Wrong Units (G20 vs G21): 25.4x scaling error between inches and millimeters
- Missing Cutter Compensation (G41/G42): Results in undersized or oversized features
よくあるご質問
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What should be confirmed before ordering What Is G-Code? Understanding CNC Programming Fundamentals?
製造開始前に、図面のバージョン、材料等級、公差、数量、重要寸法、表面仕上げ、検査要件を確認する。.
What usually drives cost in What Is G-Code? Understanding CNC Programming Fundamentals?
コストは通常、材料、段取り時間、機械時間、公差の難易度、治具、工具アクセス、仕上げ、検査、注文数量によって左右される。.
How can quality risk be reduced in What Is G-Code? Understanding CNC Programming Fundamentals?
重要なフィーチャーを明確にマーキングし、不必要な厳しい公差を避け、製造可能性を早期に確認し、重要な寸法の検査データを使用することで、品質リスクを低減します。.
