Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 617)

Using Hemisphere Milling Cycles
Chapter 24
24-11
Figure 24.4
Convex Hemisphere Finishing Using G88.6
PLUNGING AXIS
TOOL DIA,
D’
CUSP
R L
CUSP
HEIGHT
L’
Important: The tool should be positioned near the center of the convex
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 convex hemisphere, X and Y coordinates.
With a convex hemisphere, the plunge is actually a contour move to the
left along the -X axis. This move cuts along the spherical contour, axes X
and Z, at the plunge feedrate specified by the E parameter. This plunge
simultaneously moves the X and Z axes by the D’and L’amounts.
After the plunge, the control moves the tool in a 360 degree circular path,
defined by the center of the convex hemisphere and the radius of the
hemisphere, around the plunge-position.
Important: The thickness of the first rough cut is D’not the programmed
D parameter.