FANUC Series 16/18/160/180-Model C Machining Center Operators Manual

PROGRAMMING
14. FUNCTIONS TO SIMPLIFY
PROGRAMMING
B–62764EN/01
180
This cycle performs left–handed tapping. In the left–handed tapping
cycle, when the bottom of the hole has been reached, the spindle rotates
clockwise.
G74 (G98) G74 (G99)
G74 X_ Y_ Z_ R_P_ F_ K_ ;
X_ Y_: Hole position data
Z_ : The distance from point R to the bottom of the hole
R_ : The distance from the initial level to point R level
P_ : Dwell time
F_ : Cutting feedrate
K_ : Number of repeats
P
P
P
P
Initial level
Point R
Point Z
Spindle
CCW
Spindle
CCW
Point R level
Spindle CW
Spindle CW
Point Z
Point R
Tapping is performed by turning the spindle counterclockwise. When the
bottom of the hole has been reached, the spindle is rotated clockwise for
retraction. This creates a reverse thread.
Feedrate overrides are ignored during left–handed tapping. A feed hold
does not stop the machine until the return operation is completed.
Before specifying G74, use a miscellaneous function (M code) to rotate
the spindle counterclockwise.
When the G74 command and an M code are specified in the same block,
the M code is executed at the time of the first positioning operation. The
system then proceeds to the next drilling operation.
When K is used to specify the number of repeats, the M code is executed
for the first hole only; for the second and subsequent holes, the M code
is not executed.
When a tool length offset (G43, G44, or G49) is specified in the canned
cycle, the offset is applied at the time of positioning to point R.
14.1.2
Left–handed
Tapping Cycle (G74)
Format
Explanations

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