Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 608)

Using Hemisphere Milling Cycles
Chapter 24
24-2
Use the G88.5 concave milling roughing cycle to rough out a concave
pocket in a workpiece. This cycle makes multiple concentric circular cuts
at a programmed width and depth.
The G88.5 block used to rough out a concave pocket has this format:
G88.5 X__Y__Z__R__Q0_P__H__D__L__E__F__;
Where : Is :
X Y The coordinates that specify the center of the concave hemisphere in the
selected plane.
Z The coordinate (along the plunging axis) that specifies the bottom of the
hemispherical pocket. In incremental mode this parameter specifies the depth of
the pocket as measured from the start level to the pocket bottom. This
parameter must be programmed.
R Radius of the concave hemisphere.
Q0 Code specifying a concave hemisphere.
P Direction of roughing cut. This parameter determines whether the roughing cuts
are performed in a clockwise or counter-clockwise motion. P0 specifies
clockwise. P1 specifies counter-clockwise.
Important: If cutter compensation (G41/G42) was enabled prior to the
G88.5 block, it is disabled when G88.5 is enabled.
H The finish allowance that will be left on the sides of the concave hemisphere.
This finish allowance can be removed later using a G88.6 finishing cycle.
D Roughing cut thickness. This parameter specifies the maximum width of any XY
axis roughing cuts. This is an optional parameter. If not programmed, the control
uses the default thickness, which is equal to half of the current tool diameter.
Important: The roughing cut thickness can not be greater than the diameter
of the current tool. If it is, the control enters Cycle-Stop mode and displays the
error message “D-WORD LARGER THAN TOOL DIAMETER”on the CRT.
L Roughing cusp height. This value of this parameter is a measurement that
corresponds to the height of the material left along the sides of the hemisphere
after each X-Z roughing plunge.
E Plunge feedrate. This parameter determines the feedrate of any Z axis moves. If
not programmed the roughing feedrate (F) will be used.
F Roughing feedrate. This parameter determines the feedrate of any XY axis
moves. If not programmed the existing (modal) feedrate will be used.
If Q0 is programmed, the control generates a concave hemisphere. The
control makes multiple concentric circular cuts at each level of the concave
hemisphere. The depth of the pocket increases and the diameter of each
level decreases until the bottom center of the concave hemisphere is
reached.
24.1.1
Concave Hemisphere
Roughing Using G88.5