Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 604)

Using Post Milling Cycles
Chapter 23
23-10
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 rectangular post
specified by the X and Y parameters. This simultaneous move takes place
at the rapid feedrate.
The control starts the finish pass by moving the tool from the post center to
the start point of the tangential entry/exit path. This start point 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.
After the plunge operation, the tool is moved along the tangential
entry/exit path to the tangential entry/exit point on the side of the post. A
finish pass that ends at the tangential entry/exit point is then cut around the
sides of the rectangular post. The control ends the finish pass by moving
the tool from the tangential entry/exit point to the end point of the
tangential entry/exit path.
If the programmed Z depth of the post has not been reached, the tool is
simultaneously raised by the clearance amount and moved back to the
tangential entry/exit path start point at the rapid feedrate. A plunge to the
next level is then made. A finish pass is made at each L level until the
pocket bottom is reached.
When all finish passes are completed, the control simultaneously raises the
tool to the initial Z level while moving it away from the side of the post by
the clearance amount. This simultaneous move takes place at the rapid
feedrate. The control then retracts the tool at rapid feedrate in all three
axes back to the pre-cycle position of the tool.