Concept Flow - Why G-code is the language of CNC machines
Start: CNC machine receives command
↓
Interpret G-code commands
↓
Move machine parts accordingly
↓
Perform machining operation
↓
Check for next command
↓
Repeat steps
The CNC machine reads G-code commands step-by-step, moves its parts as instructed, performs machining, and repeats until all commands are done.
Execution Sample
CNC Programming
G01 X10 Y5 F1500
G02 X20 Y5 I5 J0
M30
This G-code moves the tool in a straight line, then in a circular arc, then stops the program.
Execution Table
Step
G-code Command
Action
Machine Movement
Output
1
G01 X10 Y5 F1500
Linear move to X=10, Y=5 at feed 1500
Tool moves straight to (10,5)
Position updated to (10,5)
2
G02 X20 Y5 I5 J0
Clockwise arc to X=20, Y=5 with center offset I=5, J=0
Tool moves in arc to (20,5)
Position updated to (20,5)
3
M30
Program end
Machine stops
Program finished
💡 M30 command ends the program, so machine stops execution.
Variable Tracker
Variable
Start
After Step 1
After Step 2
After Step 3
Position
(0,0)
(10,5)
(20,5)
(20,5)
Feed Rate
Default
1500
1500
1500
Program State
Running
Running
Running
Stopped
Key Moments - 3 Insights
Why does the machine stop after the M30 command?
Because M30 is the standard G-code command to end the program, as shown in execution_table step 3 where the machine stops.
How does the machine know where to move during G02 command?
The machine uses the X and Y target coordinates plus I and J offsets to calculate the arc path, as detailed in execution_table step 2.
Why is the feed rate important in G01 command?
Feed rate controls the speed of the tool movement, ensuring precise machining, shown in execution_table step 1 where F1500 sets the speed.
Visual Quiz - 3 Questions
Test your understanding
Look at the execution_table, what is the machine position after step 1?
A(0,0)
B(20,10)
C(10,5)
D(5,0)
💡 Hint
Check the 'Machine Movement' and 'Output' columns in execution_table row 1.
At which step does the machine stop executing commands?
AStep 3
BStep 1
CStep 2
DNever stops
💡 Hint
Look at the 'Program State' in variable_tracker after step 3.
If the feed rate F1500 was changed to F3000 in step 1, what would change in the execution_table?
AThe tool would move slower
BThe tool would move faster
CThe machine would stop earlier
DNo change in movement speed
💡 Hint
Feed rate controls speed; see 'Feed Rate' variable in variable_tracker after step 1.
Concept Snapshot
G-code is the language CNC machines use to control movements.
Commands like G01 move in straight lines; G02/G03 move in arcs.
Feed rate (F) controls speed.
M30 ends the program.
The machine reads commands step-by-step and acts accordingly.
Full Transcript
G-code is the standard language for CNC machines. It tells the machine how to move tools precisely. Commands like G01 move the tool in a straight line to specified coordinates at a set speed. G02 moves the tool in a clockwise arc using center offsets. The M30 command stops the program. The machine updates its position and state after each command. This step-by-step reading and execution allow CNC machines to perform complex machining tasks accurately.
