In the world of CNC (Computer Numerical Control) milling, precision and accuracy are paramount. Two essential commands that facilitate intricate movements are G02 and G03, which control circular interpolation in a clockwise and counter-clockwise direction, respectively. These commands allow the machine to create arcs and circles, which are fundamental in producing complex geometrical shapes.

Usage Format

The G02 and G03 commands follow a specific syntax to define the circular motion on a CNC mill. The general format is:

• G02 for clockwise (CW) circular interpolation
• G03 for counter-clockwise (CCW) circular interpolation

The commands can be used with either R or IJK notation to specify the arc’s radius or its center point relative to the starting position.

Explanation

G02 (Clockwise Circular Interpolation):

• Moves the tool in a circular path in a clockwise direction.
• Requires the endpoint of the arc (X, Y coordinates) and either the radius ® or the center point offsets (I, J).

G03 (Counter-Clockwise Circular Interpolation):

• Moves the tool in a circular path in a counter-clockwise direction.
• Similar to G02, it requires the endpoint and the radius or center point offsets.

The choice between using R or IJK depends on the complexity of the movement and the preference of the programmer.

Example

Here’s a simple text diagram and code example to illustrate the use of G02 and G03:

(Start)
   |
   |          (End)
   |         /
   |        /
   |       / R
   |      /
   |     /
   +----+
(Tool Path for G02)

G02 Example Code:

N10 G90 G17 ; Set to absolute mode and select XY plane
N20 G01 X0 Y0 F20 ; Move to start point
N30 G02 X2 Y2 I1 J0 F15 ; CW arc to endpoint with center offset I1 J0

(Start)
   |
   |\
   | \
   |  \ R
   |   \
   |    \
   +-----+
(Tool Path for G03)

G03 Example Code:

N10 G90 G17 ; Set to absolute mode and select XY plane
N20 G01 X0 Y0 F20 ; Move to start point
N30 G03 X2 Y2 I1 J0 F15 ; CCW arc to endpoint with center offset I1 J0

In these examples, the tool moves from the starting point at X0 Y0 to the endpoint at X2 Y2. The arc’s center is offset by I1 J0 from the starting point, creating a quarter-circle path. The feed rate is set to 15 for the arc movements.