G60 – Unidirectional Approach

Author:

In CNC machining, circular interpolation is a common operation that involves moving the tool along a circular path. This can be done using G02 (clockwise) or G03 (counterclockwise) codes, along with the coordinates of the center point and the end point of the arc. However, sometimes it is necessary to control the direction of the tool approach to the arc, especially when there are multiple arcs in the same plane. This is where G60 – Unidirectional Approach comes in handy.

Usage format

The usage format of G60 is as follows:

G60 G02/G03 X__ Y__ I__ J__ F__

or

G60 G02/G03 X__ Y__ R__ F__

where:

  • G60: Unidirectional Approach
  • G02/G03: Clockwise/Counterclockwise circular interpolation
  • X, Y: Coordinates of the end point of the arc
  • I, J: Coordinates of the center point of the arc relative to the start point
  • R: Radius of the arc
  • F: Feed rate

Explanation

The G60 code tells the CNC machine to move the tool in a unidirectional approach to the arc, meaning that the tool will always enter the arc from the same side, regardless of the previous tool position. This can help to avoid collisions, reduce tool wear, and improve surface finish.

The G60 code must be used in conjunction with G02 or G03, and it must precede them in the same block. The G60 code will remain active until it is canceled by another G code or by a program stop.

The direction of the unidirectional approach depends on the sign of the I or J value, or the R value, depending on the format used. For example, if G02 is used with a positive I value, the tool will approach the arc from the left side. If G03 is used with a negative J value, the tool will approach the arc from the bottom side. If G02 is used with a negative R value, the tool will approach the arc from the inside. If G03 is used with a positive R value, the tool will approach the arc from the outside.

Example

Here is an example of using G60 to perform a circular interpolation with a unidirectional approach. The tool will move along four arcs in a square pattern, always entering the arc from the outside.

N10 G90 G17 G21 ; Set absolute mode, XY plane, and metric units
N20 G00 X0 Y0 ; Rapid move to the origin
N30 G60 G02 X10 Y10 I10 J0 F100 ; Move clockwise to (10, 10) with a radius of 10 and a unidirectional approach from the left
N40 G60 G02 X0 Y20 I0 J10 F100 ; Move clockwise to (0, 20) with a radius of 10 and a unidirectional approach from the bottom
N50 G60 G02 X-10 Y10 I-10 J0 F100 ; Move clockwise to (-10, 10) with a radius of 10 and a unidirectional approach from the right
N60 G60 G02 X0 Y0 I0 J-10 F100 ; Move clockwise to (0, 0) with a radius of 10 and a unidirectional approach from the top
N70 M30 ; End of program

Here is a text diagram to illustrate the tool path and the direction of the unidirectional approach:

    Y
    ^
    |
20  |   /----\
    |  /      \
10  | /        \
    |/          \
 0 -+------------+---->
    |          / |    X
-10 | \        / |
    |  \      /  |
-20 |   \----/   |
    |            |
    |            |

 

Leave a Reply

Your email address will not be published. Required fields are marked *