Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 589)

Using Pocket Milling Cycles
Chapter 22
22-17
Important: The rectangular pocket does not have to be parallel to the axes
of the selected plane. It may be rotated by rotating the work coordinate
system (G68). Refer to chapter 13 for additional information on rotating
the work coordinate system.
In a finishing cycle, a smooth entry to and exit from the finish contour is
accomplished by having the tool approach and leave the finish contour
along a tangential arc. The radius of this arc is set equal to the tool
diameter by the control. The tangential entry/exit point is along the -X or
-Y axis depending on which axis intersects the center of the longer side of
the rectangular pocket. If the pocket is square, the tangential entry/exit
point is along the -X axis.
Figure 22.6
Rectangular Pocket Finishing Using G88.2
TANGENTIAL ENTRY/
EXIT PATH
FINISH
CUT
(X, Y)
TOOL RADIUS
X
Y
I
J
Important: The tool should be positioned near the center of the pocket
prior to the G88.2 block. The Z coordinate of this position determines the
initial Z level or top of the pocket. This is the pre-cycle position of the
tool. The pre-cycle position must be at some depth other than the cycles
programmed final depth or an error is generated.