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

Positioning to the intermediate or reference positions are performed at the
rapid traverse rate of each axis.
Therefore, for safety, the tool nose radius compensation, and tool offset
should be cancelled before executing this command.
In a system without an absolute–position detector, the first, third, and
fourth reference position return functions can be used only after the
reference position return (G28) or manual reference position return (see
III–3.1) is made. The G30 command is generally used when the automatic
tool changer (ATC) position differs from the reference position.
G27 command positions the tool at rapid traverse rate. If the tool reaches
the reference position, the reference position return lamp lights up.
However, if the position reached by the tool is not the reference position,
an alarm (No. 092) is displayed.
The lamp for indicating the completion of return does not go on when the
machine lock is turned on, even when the tool has automatically returned
to the reference position. In this case, it is not checked whether the tool
has returned to the reference position even when a G27 command is
When the G28 command is specified when manual return to the reference
position has not been performed after the power has been turned on, the
movement from the intermediate point is the same as in manual return to
the reference position.
In this case, the tool moves in the direction for reference position return
specified in parameter ZMIx (bit 5 of No. 1006). Therefore the specified
intermediate position must be a position to which reference position
return is possible.
In an offset mode, the position to be reached by the tool with the G27
command is the position obtained by adding the offset value. Therefore,
if the position with the offset value added is not the reference position, the
lamp does not light up, but an alarm is displayed instead. Usually, cancel
offsets before G27 is commanded.
When the machine tool is an inch system with metric input, the reference
position return lamp may also light up even if the programmed position
is shifted from the reference position by least input increment. This is
because the least input increment of the machine is smaller than its least
command increment.
See III–3.1.
D Reference position
return (G28)
D 2nd, 3rd, and 4th
reference position return
D Reference position
return check (G27)
D Status the machine lock
being turned on
D First return to the
reference position after
the power has been
turned on (without an
absolute position
D Reference position
return check in an offset
D Lighting the lamp when
the programmed position
does not coincide with
the reference position
D Manual reference
position return

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