Computer Numerical Control (CNC) machines revolutionized the manufacturing industry by allowing for precision machining of parts. Among the various operations, arc programming is a critical component for creating rounded features on parts. The G02 and G03 codes are used to program clockwise and counterclockwise arcs, respectively.
Usage Format
The general format for these codes is as follows:
 G02 for a clockwise arc
 G03 for a counterclockwise arc
The codes are followed by X, Y coordinates for the endpoint of the arc, and either the radius ® or the I, J coordinates for the center point of the arc.
Explanation
 G02 X_Y_R: Moves the tool in a clockwise arc to the end point (X,Y) with a specified radius ®.
 G03 X_Y_R: Moves the tool in a counterclockwise arc to the end point (X,Y) with a specified radius ®.
Alternatively, I and J denote the distance from the starting point to the center of the arc, along the X and Y axes, respectively.
Example
Let’s consider a scenario where we need to move the tool in a clockwise arc from the current position to an endpoint at X100, Y100 with a radius of 50 units.
G02 X100 Y100 R50
The text diagram below illustrates the movement:
Starting Point


_________
/
/
/
End Point
For a counterclockwise movement with the same parameters, the code would be:
G03 X100 Y100 R50
And the text diagram would be inverted accordingly.