Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 561)

Cutter Diameter Compensation
(G40, G41, G42)
Chapter 21
21-43
If a tool becomes excessively worn, broken, or if any other reason requires
the changing of the programmed tool radius, the cutter compensation
should be cancelled and reinitialized after the tool has been changed. The
following section describes the resulting tool path if, for some reason, it is
desirable to program a change in cutter radius during cutter compensation.
Important: Slight overcutting may occur during Cutter Compensation,
depending on the programmed path at the point where the change in cutter
radius was made. To avoid overcutting, we recommend that you use a
Mid--Start Program until the point of tool breakage.
See section 3.2 on changing the active tool offset and section 21.1 on
changing the programmed compensation diameter offset number.
Figure 21.40 through Figure 21.42 are representations of the resulting tool
paths after the programming of a change in the radius of the cutting tool.
Assume in these figures that the programmed change to the tool radius is
entered in block N11 which also contains the motion as described in the
figure. The tool path taken when changing tool radius is dependant on the
move immediately before the change in radius was programmed, the move
that the change in radius was programmed in, and whether any generated
motion blocks were made between these tool paths.
Figure 21.40 describes the tool path when the programmed moves are
linear-to-linear.
Figure 21.40
Linear-to-Linear Change in Cutter Radius During Compensation
No control-generated
motion blocks With control-generated
motion blocks
Compensated
path
Programmed
path
N10
N11
N12
Compensated
path
Programmed
path
Generated
blocks
N10
N11
N12
N10
N11 D_
N12 N10
N11 D_
N12
r
1
r
1
r
1
r
1
r
2
r
2
r
1
r
1
r
2
r
2
21.6.4
Changing Cutter Radius
During Compensation