# Fanuc Series 15i/150i-MA (Programming) Operators Manual

4.INTERPOLATION FUNCTIONS PROGRAMMING B-63324EN/03
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WARNRING
1. Consider lines L1, L2, and L3. X is the distance the
tool moves per time unit at the feedrate specified with
address F in the Cartesian coordinate system. As
the tool moves from L1 to L2 to L3, the angle at which
the tool moves per time unit corresponding to X in
the Cartesian coordinate system increases from θ1
to θ2 to θ3.
In other words, the C-axis component of the feedrate
becomes larger as the tool moves closer to the
center of the workpiece. The C component of the
feedrate may exceed the maximum cutting feedrate
for the C-axis because the tool movement in the
Cartesian coordinate system has been converted to
the tool movement for the C-axis and the X-axis.
L : Distance (in mm) between the tool center and
workpiece center when the tool center is the
nearest to the workpiece center
R : Maximum cutting feedrate (deg/min) of the C axis
Then, a speed specifiable with address F in polar
coordinate interpolation can be given by the formula
below.
Specify a speed allowed by the formula. The
formula provides a theoretical value; in practice, a
value slightly smaller than a theoretical value may
need to be used due to a calculation error.
F<L×R×
180
π
imm/min j
The speed can be controlled so as to prevent the
issue of alarm OT512 (excessive speed). See II-
5.5..2 for details.
L1
L2
L3
θ3
θ2
θ1
X