Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 593)

Using Pocket Milling Cycles
Chapter 22
22-21
If the programmed R parameter is greater than the tool radius, this cycle is
processed similar to a G88.2 finishing cycle for a rectangular pocket. The
difference being that the R parameter programmed in a slot finishing cycle
specifies the radius of the arc at the end of the slot verses the radius of the
corners in a rectangular finishing cycle. The control cuts an arc at the short
side a the rectangular pocket based on the programmed R parameter and
the arc-center determined by the control.
If the programmed R parameter is equal to the tool radius, the control
simultaneously raises the tool by the clearance amount (AMP selectable,
refer to the literature provided by your system installer) while moving it at
the rapid feedrate to the arc-center at the -X or -Y end of the slot. This
position 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 a finishing cut is made at the finishing feedrate
specified by the F parameter to the opposite arc-center at the +X or +Y end
of the slot.
The tool is then raised to the initial Z level plus the clearance amount. If
the programmed Z depth of the slot has not been reached, the tool is moved
at rapid feedrate back to the plunge-position. A plunge to the next
incremental L level or to the programmed Z level is made. Another
finishing cut is made at the finishing feedrate to the arc-center at the +X or
+Y end of the slot.
This process is repeated at each L level until the sides of the slot are
finished. When all finish passes are completed, the control retracts the tool
at rapid feedrate in all three axes back to the pre-cycle position of the tool.
END OF CHAPTER