Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 545)

Cutter Diameter Compensation
(G40, G41, G42)
Chapter 21
21-27
If the last programmed move is circular (an arc), the tool is positioned at
right angles to a tangent line drawn from the end-point of that circular
move.
Figure 21.22
Tool Path For Exit Move Arc-to-Straight Line
•
•
•
•
End-point
End-point
End-point
End-point
0
• • •
90
90
• • •
180
180
• • •
270
270
• • •
360
Programmed path
Programmed path
Programmed path
Programmed
Path
G42 G41
G41
G42
G42 G41
G41
G42
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
•
End-point
0
• • •
90
Programmed path
G41
G42
r
r
r
G39.1 (Circular Generated Block) G39 (Linear Generated Block)
r
•
End-point
270
• • •
360
Programmed path
G41
G42
r
r
r
G39.1 (Circular Generated Block) G39 (Linear Generated Block)
Figure 21.21 and Figure 21.22 assume that the number of blocks not
containing axes motion in the current plane, following G40 before the exit
move takes place, does not exceed an amount selected in AMP by the
system installer. If the number of non-motion blocks following G40
exceeds the limit, the control generates its own exit move. This may often
cause over-cutting of the part.