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

4.INTERPOLATION FUNCIONS PROGRAMMING B-63324EN/03
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- Circular interpolation (G02,G03)
In the cylindrical interpolation mode, circular interpolation is possible
with the rotation axis and another linear axis. Radius R is used in
commands in the same way as described in II-4.4.
The unit for a radius is not degrees but millimeters (for metric input) or
inches (for inch input).
@Example jCircular interpolation between the Z axis and C axis
For the C axis of parameter (No.1022), 5 (axis parallel with the X
axis) is to be set. In this case, the command for circular
interpolation is
G18 Z_ C_ ;
G02(G03) Z_ C_ R_ ;
For the C axis of parameter (No.1022), 6 (axis parallel with the Y
axis) may be specified instead. In this case, however, the
command for circular interpolation is
G19 C_ Z_ ;
G02(G03) Z_ C_ R_ ;
- Cylindrical interpolation accuracy
In the cylindrical interpolation mode, the amount of travel of a rotary
axis specified by an angle is once internally converted to a distance of a
linear axis on the outer surface so that linear interpolation or circular
interpolation can be performed with another axis. After interpolation,
such a distance is converted back to an angle. For this conversion, the
amount of travel is rounded to a least input increment.
So when the radius of a cylinder is small, the actual amount of travel
can differ from a specified amount of travel. Note, however, that such
an error is not accumulative.
If manual operation is performed in the cylindrical interpolation mode
with manual absolute on, an error can occur for the reason described
above.
The actual MOTION REV 2×2π×R
Amount = ------------------× Specified value× -----------------
of travel 2×2π×R MOTION REV
MOTION REV:The amount of travel per rotation of the rotation axis
(Setting value of parameter No. 1260)