Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 583)

Using Pocket Milling Cycles
Chapter 22
22-11
Figure 22.4
Circular Pocket Roughing Using G88.1
Plunge Position
(X, Y)
D/2
R
D D
H+TR
X
Y
Important: The tool should be positioned near the center of the pocket
prior to the G88.1 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.
From the pre-cycle position, the control simultaneously raises the tool by
the clearance amount (AMP selectable, refer to the literature provided by
your system installer) while moving it to the center of the circular pocket
specified by the X and Y parameters. This simultaneous move takes place
at the rapid feedrate. The center of the pocket is the plunge position, the
position where the plunge to the programmed depth takes place.
If L is programmed, the tool plunges along the Z axis to the incremental
depth specified by the L parameter. If L is not programmed, the tool
plunges along the Z axis to the pocket depth specified by the Z parameter.
This move takes place at the plunge feedrate specified by the E parameter.
If E is not programmed, the plunge takes place at the roughing feedrate.
After the plunge operation, the control performs a single-axis cut outwards
along the -X axis of the circular pocket. The control then moves the tool in
a 360 degree circular path, defined by the center of the circular pocket and
it’s radius, around the plunge- position.