When programming CNC programs, G02 and G03 are another type of interpolation command that needs to be learned. These commands control the tool to move along an arc at a given speed to reach the target point. The format is as follows:
G02 X_Y_ R_F_; G03 X_Y_ R_F_;
In the above format, X_Y_ represents the position of the target point. When executing this code, the tool moves along an arc with a radius of R_ at the set speed F to reach the target point X_Y_. G02 represents clockwise interpolation, while G03 represents counterclockwise interpolation. When the central angle of the arc is less than or equal to 180 degrees, the R value is positive. For concave arcs, negative values should be used. When machining a complete circle, the following format is used: G02 X_Y_ I_J_F_; G03 X_Y_ I_J_F_;
In the second format, R value is not explicitly used. Instead, I represents the difference in X coordinates between the center of the circle and the starting point, and J represents the difference in Y coordinates between the center and the starting point. Let's practice the circular interpolation command with the arcs and complete circles shown in the following diagram.
Example 1: The tool moves from point A to point B along Arc 1. Since this arc is a concave arc, the R value is negative. G02 X90Y50R-40F500;
Example 2: The tool moves from point A to point B along Arc 5. Although the endpoint coordinates are known, the radius is not directly indicated. In this case, the I and J programming method can be used. G02 X90Y50I20J-20F500;
To determine the coordinates of the arc center O3, observe whether the center is in the positive or negative X direction from the starting point A. In this case, O3 is 20 in the positive X direction from point A, so I20 is used. In the Y direction, O3 is 20 in the negative direction from point A, so J-20 is used. Alternatively, you can calculate the coordinates by substituting the X and Y coordinates of the points into the formula.
Similarly, you can follow the same principles to program the machining paths for Arcs 4, 2, 6, and 3, as well as the complete circles. The shorthand notations for the examples are provided for your reference.
The program for machining the above arcs and complete circles as a contour milling program is as follows:
G90G54G40G1Z100F1000M03S3000 G0X0Y0 X90Y40 Z3 G1Z-2F50 G02I40F500; G02I20J-20F500; G02J-40F500; G1Z5F200 G1Z100F1000 M5 M30
The initial state of the workpiece before machining is as shown in the following diagram:
The simulated machining result is shown in the following figure:
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