Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 581)

Using Pocket Milling Cycles
Chapter 22
22-9
Figure 22.3
Slot Roughing Using G88.1
H+TR
D
D/2
D/2
D
(X, Y)
Plunge Position
R
Y
X
I
J
Important: The tool should be positioned at the center of the slot 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.
If the programmed R parameter is greater than the tool radius, this cycle is
processed similar to a G88.1 roughing cycle for a rectangular pocket. The
difference being that the R parameter programmed in a slot roughing cycle
specifies the radius of the arc at the end of the slot verses the radius of the
corners in a rectangular roughing cycle. The control cuts an arc at the
short side of 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 to
the arc-center at the -X or -Y end of the slot. This simultaneous move
takes place at the rapid feedrate. This position is the plunge-position, the
position where the plunge to the programmed depth takes place.