Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 398)

Axis Motion
Chapter 14
14-22
Polar positioning is done by defining a vector using a radius and angle
value. The head (or end) of the vector defined by the radius and angle
values is used as the end point of a polar move.
In both incremental and absolute mode the cutting tool will follow a path
starting at the end point of the last move and ending at the head of the
vector defined by the radius and angle. How the tool reaches that endpoint
is determined by the current positioning mode (G00, G01, G02, or G03).
Figure 14.11
Polar Vector Defining End Point Of Tool Path
End point of
polar move
Current tool
position
Vector angle
programmed
with Y word
Polar defined vector
Path taken if a
linear mode (G00, G01)
is active
Vector angle
programmed
with X word
X
Y
The control’s interpretation of the specified angle and radius values used to
define the vector is dependant on whether programming is in incremental
mode or absolute mode. It is possible to mix incremental and absolute
modes in polar programming, though for clarity this practice is not
recommended.
If programming in incremental mode (G91):
The radius is measured from the current tool position at the specified
angle to define a vector.
The angle is referenced relative to the last programmed angle (note the
last programmed angle defaults to zero degrees upon entry to polar
programming mode).