Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 615)

Using Hemisphere Milling Cycles
Chapter 24
24-9
Figure 24.3
Concave Hemisphere Finishing Using G88.6
PRE-CYCLE
POSITION
INITIAL Z-LEVEL
R
TR+D’
(X, Y)
Y
X
L’
D’
Z
R
Important: The tool should be positioned near the center of the concave
hemisphere prior to the G88.6 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 control raises the tool by the clearance amount (AMP selectable, refer
to system installers literature) and moves it at the rapid feedrate to the
center of the concave hemisphere, X and Y coordinates.
The control initially moves the tool down L’from the initial Z level and
offsets it from the side of the concave hemisphere by D’. A 360 degree
circular path is cut, defined by the center of the concave hemisphere and
the radius of the hemisphere, that ends at the -X axis.