The CNC tool moves from start to end point following an arc defined by center and radius, creating a smooth curved contour.
Execution Sample
CNC Programming
G02 X15 Y10 I5 J0 F100
This CNC command moves the tool in a clockwise arc to X=15, Y=10 with center offset I=5, J=0 at feed rate 100.
Execution Table
Step
Command Part
Action
Position
Tool Path Shape
1
G02
Select clockwise arc move
Current position (e.g. X5 Y10)
Start arc
2
X15 Y10
Set arc end point
X=15, Y=10
Arc end point defined
3
I5 J0
Set arc center offset from start
Center at X=10, Y=10
Arc center defined
4
F100
Set feed rate
Speed set
Movement speed set
5
Execute move
Tool moves along arc
Positions between start and end
Smooth curved path created
6
End
Tool reaches end point
X=15, Y=10
Smooth contour completed
💡 Tool reaches end point X=15 Y10, arc move complete with smooth contour
Variable Tracker
Variable
Start
After Step 2
After Step 3
After Step 5
Final
Position
X5 Y10
X15 Y10 (end point set)
Center offset I5 J0 set
Moving along arc path
X15 Y10 (end)
Feed Rate
Default
Default
Default
100
100
Tool Path
None
None
Arc center defined
Arc path traced
Smooth arc contour
Key Moments - 3 Insights
Why does the tool move in a curve instead of a straight line?
Because the command G02 specifies a clockwise arc move with center offsets I and J, the tool follows a circular path, as shown in execution_table step 5.
What do the I and J values represent in the arc command?
I and J are the distances from the start point to the arc center along X and Y axes respectively, defining the arc's radius and center, as seen in execution_table step 3.
How does the feed rate affect the arc movement?
The feed rate sets the speed of the tool movement along the arc path, ensuring smooth motion without abrupt changes, as indicated in execution_table step 4.
Visual Quiz - 3 Questions
Test your understanding
Look at the execution_table, at which step is the arc center defined?
AStep 3
BStep 2
CStep 4
DStep 5
💡 Hint
Check the 'Command Part' column for I and J values defining the center.
According to variable_tracker, what is the tool position after step 5?
AX5 Y10
BMoving along arc path
CX15 Y10
DCenter offset I5 J0
💡 Hint
Look at the 'Position' variable value after step 5.
If feed rate F100 was changed to F50, what would change in the execution_table?
AArc center would change
BEnd position would change
CStep 4 would show feed rate 50
DTool path shape would become straight
💡 Hint
Feed rate affects speed, check step 4 in execution_table.
Concept Snapshot
CNC arcs use G02/G03 commands to move tool along circular paths.
I and J define arc center offsets from start point.
Feed rate (F) controls movement speed.
Arcs create smooth contours by following curved tool paths.
Straight lines use G01; arcs use G02 (clockwise) or G03 (counterclockwise).
Full Transcript
This lesson shows how CNC arcs create smooth contours by moving the tool along a circular path. The G02 command tells the machine to move clockwise along an arc. The I and J values set the center of the arc relative to the start point. The feed rate sets how fast the tool moves. Step by step, the tool moves from start to end point following the arc, creating a smooth curve instead of a straight line. This smooth contour is important for precise machining of curved shapes.
Practice
(1/5)
1. Why do arcs create smoother contours in CNC programming compared to straight lines?
easy
A. Because arcs follow a curved path defined by center points, avoiding sharp corners.
B. Because arcs use more power to cut materials.
C. Because arcs are faster to program than straight lines.
D. Because arcs always move in a straight line.
Solution
Step 1: Understand the shape difference
Arcs create curves by moving along a circular path, unlike straight lines that create sharp angles.
Step 2: Recognize the effect on smoothness
Curved paths avoid abrupt changes in direction, resulting in smoother contours.
Final Answer:
Because arcs follow a curved path defined by center points, avoiding sharp corners. -> Option A
0