Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 393)

Axis Motion
Chapter 14
14-17
If an A axis position is programmed, the A axis will be rotated to the
specified angle. If the A and X axes are programmed together in the same
block, then a vector motion will result. around the circumference of the
part.
If G02 or G03 circular interpolation is made active while in G16.1
cylindrical interpolation mode, a circular cut can be made around the
circumference of the part (such as the contour cut in Figure 14.9). This is
accomplished by programming the A and X axis endpoints along with the
desired circle radius R as described in section 14.1.3 . Note that the R
parameter now defines the radius of the circular path to be cut, not the feed
axis position.
Important: When programming circular interpolation in G16.1 mode,
only radius programming (using R) may be used. Integrand programming
(using I, J, K) is not allowed and will generate the error message “CIRCLE
PROGRAMMING ERROR”. Refer to section 14.1.3 .
Important: A axis motion is programmed as an angular value. When
programming circular interpolation in G16.1 mode, this angular value has
to be derived from an A axis arc length (based on the cutting radius).
Refer to Example 14.7.
To perform G02/G03 circular interpolation while in G16.1 mode, the linear
axis (X) and the rotary axis (A) must move to the endpoint of the arc of
radius R made on the side of the cylinder.
In incremental mode (G91) the A axis arc length along with the
programmed X move length, must position the A and X axes at a legal
endpoint for the arc radius defined by the R value in the G02/G03 block.
In absolute mode (G90) the coordinate defined by the A axis arc along
with the coordinate programmed for the X axis, must position the A and X
axes at a legal endpoint for the arc radius defined by the R value in the
G02/G03 block.
When cylindrical interpolation is activated, the circle plane is set to XA.
The A and X axes become the two axes of the circle plane and remain so,
as long as the G16.1 mode is active. If the active plane is changed, the
change will not become effective until the G16.1 mode is cancelled, and
will be superceded if the G16.1 plane is reactivated.
Canceling Cylindrical Interpolation
Cancel cylindrical interpolation by programming a G15. The G15 program
block can not contain axis words. Note that the G15 program block can
cancel other modal group 15 functions such as polar programming (refer to
appendix C for a complete listing of modal group 15 G--codes).