Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 584)

Using Pocket Milling Cycles
Chapter 22
22-12
After completing the 360 degree circular path, the control makes a
single-axis rough cut outwards along the -X axis then cuts another 360
degree circular path. This process is repeated until the sides of the pocket,
less the finish allowance H, are reached. The tool is then simultaneously
raised by the clearance amount and moved at rapid feedrate back to the
plunge-position. This completes machining of one L level.
The width of the first roughing cut is equal to the programmed rough cut
thickness, D, divided by two then multiplied by 95% ((D/2) x (.95)). The
width of the last roughing cut is equal to the tool radius plus the finish
allowance (H + TR).
The width of the remaining roughing cuts is calculated by the control
based on the remaining area to be roughed-out and the programmed rough
cut thickness, D. The control divides the remaining area by D to calculate
the number of roughing cuts needed to rough out this area. The control
then adjusts the width and number of these cuts until an even number of
roughing cuts is achieved. The width of these cuts will always be equal to
or less than the programmed rough cut thickness, D.
If the programmed Z depth of the pocket has not been reached, another
plunge along the Z axis to the next L level takes place. This level is then
machined as described in the previous paragraphs. This process is repeated
until the pocket is machined out.
Once the pocket has been machined out, the control simultaneously raises
the tool to the initial Z level plus the clearance amount while moving it
away from pocket edge by the clearance amount. This simultaneous move
takes place at the rapid feedrate. The tool is then moved at rapid feedrate
simultaneously along the X, Y, and Z axes to the pre-cycle position of the
tool.