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

5.FEED FUNCTIONS PROGRAMMING B-63324EN/03
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5.6.2 Automatic Velocity Control During Polar Coordinate Interpolation
If the feedrate component of a rotation axis exceeds a maximum
allowable cutting feedrate in polar coordinate interpolation mode, an
OT512 alarm (feedrate excess alarm) is issued. However, this function
can automatically control the feedrate so that a feedrate excess alarm is
not issued.
Explanation
- Automatic Override
If the feedrate component of a rotation axis exceeds a maximum
allowable feedrate (obtained by multiplying a maximum allowable
cutting feedrate by an allowance rate specified in parameter No. 1056),
the following override is automatically applied:
Override = (maximum allowable feedrate)/(feedrate component of
rotation axis) x 100 (%)
- Automatic velocity clamp
When the velocity for the rotation axis exceeds the maximum cutting
feedrate even after the method in automatic override is used, the
velocity is clamped so that it does not exceed the maximum cutting
feedrate.
This function is used only when the center of the tool is very close to
that of the rotation axis.
C-axis
A
BCD
X-axis
-10.
+10.
Example
G90 G00 X10.0 C0. ;
G12.1 ;
G01 C0.1 F1000 ;
X-10.0 :
G13.1 ;
Fig.5.6.2 (a) Automatic velocity control during polar coordinate
interpolation
For example, the above program is executed after the maximum cutting
feedrate for the rotation axis is specified as 360 (3600 deg/min), and the
permissible ratio of automatic override during polar coordinate
interpolation (parameter 1056) is specified as 0 (90%). In this case, the
automatic override starts at point A (X = 2.273), and automatically
clamping the velocity starts at point B (X = 0.524). The minimum
value of the automatic override is 3%. The velocity remains clamped
up to point C (X = -0.524), and the automatic override is applied up to
point D (X = -2.273).
(The above coordinates are Cartesian coordinate.)