Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 616)

Using Hemisphere Milling Cycles
Chapter 24
24-10
If the programmed Z depth of the pocket has not been reached, another
plunge takes place simultaneously along the X and Z axes to the next L’
level. Another 360 degree circular path is cut. This process is repeated
until the programmed Z depth of the concave hemisphere is reached, at
which time the tool is moved at rapid feedrate along the Z axis back to the
initial Z level. The tool is then moved at rapid feedrate along the X and Y
axes to its pre-cycle position. This completes the finishing cycle.
Use the G88.6 convex milling finishing cycle to finish a convex pocket in
a workpiece. This cycle is typically used to remove the finish allowance
that was left on the sides of the convex hemisphere during the G88.5
roughing cycle.
The G88.6 block used to finish a convex pocket has this format:
G88.6 X__Y__Z__R__Q1_P__H__L__E__F__;
Where : Is :
X Y The coordinates that specify the center of the convex hemisphere in the selected
plane.
Z The coordinate (along the plunging axis) that specifies the bottom of the
hemispherical pocket.
R Radius of the convex hemisphere.
Q1 Code specifying a convex hemisphere.
P Direction of finishing cut.
H Finish allowance.
L Finishing cusp height.
E Plunge feedrate.
F Finishing feedrate.
If Q1 is programmed, the control makes a finish pass around the sides of a
convex hemisphere. The control makes multiple circular finish cuts at
each level of the convex hemisphere. The depth of the pocket and the
diameter of each level increases until the outer diameter of the convex
hemisphere is reached.
Prior to each finish plunge, the control computes a delta finish cut
thickness, D’, and a delta plunge depth, L’. These computations are based
on the cusp height (L parameter) and the hemisphere radius (R parameter)
programmed in the G88.6 block, and the tool radius programmed prior to
the G88.6 block.
24.2.2
Convex Hemisphere
Finishing Using G88.6