# FANUC Series 16/18/160/180-Model C for Lathe Operator Manual

PROGRAMMING
B–62754EN/01
4. INTERPOLATION FUNCTIONS
47
The distance between an arc and the center of a circle that contains the arc
can be specified using the radius, R, of the circle instead of I, J, and K.
In this case, one arc is less than 180
°, and the other is more than 180° are
considered. An arc with a sector angle of 180
°or wider cannot be
specified. If Xp, Yp, and Zp are all omitted, if the end point is located at
the same position as the start point and when R is used, an arc of 0
°is
programmed
G02R ; (The cutter does not move.)
r=50mm
End point
Start point
r=50mm
X
Z
For arc (1) (less than 180°)
G02 W60.0 U10.0 R50.0
F300.0 ;
For arc (2) (greater than 180°)
An arc with a sector angle of 180°
or wider cannot be specified
within a single block.
(2)
(1)
The feedrate in circular interpolation is equal to the feed rate specified by
the F code, and the feedrate along the arc (the tangential feedrate of the
arc) is controlled to be the specified feedrate.
The error between the specified feedrate and the actual tool feedrate is
±2% or less. However, this feed rate is measured along the arc after the
tool nose radius compensation is applied
If I, J, K, and R addresses are specified simultaneously, the arc specified
by address R takes precedence and the other are ignored.
If an axis not comprising the specified plane is commanded, an alarm is
displayed.
For example, when a ZX plane is specified in G–code B or C, specifying
the X–axis or U–axis (parallel to the X–axis) causes P/S alarm No. 028
to be generated.
If the difference in the radius between the start and end points of the arc
exceeds the value specified in parameter No. 3410, P/S alarm No. 020 is
generated.
If the end point is not on the arc, the tool moves in a straight line along
one of the axes after reaching the end point.
If an arc having a central angle approaching 180 is specified with R, the
calculation of the center coordinates may produce an error. In such a case,
specify the center of the arc with I, J, and K.
D  
D Feedrate
Restrictions