
B–63833EN–1/02
9. SPINDLE SPEED FUNCTION
540
Rigid tapping is classified into two types: rigid tapping in feed per
rotation mode (G99) and rigid tapping in feed per minute mode (G98).
Example)
The example below specifies rigid tapping in feed per rotation mode for
cutting a thread with a lead of 1 mm at a spindle speed of 1,000 min
–1
.
O0001 ;
G99 ;
⋅
⋅
⋅
M29 S1000 ;
G84 Z–100. R–20. F1. ;
⋅
⋅
⋅
G80 ;
The example below specifies rigid tapping in feed per minute mode for
cutting the same thread at the same spindle speed as above. (In feed per
minute mode, F/S determines the thread lead.)
O0002 ;
G98 ;
⋅
⋅
⋅
M29 S1000 ;
G84 Z–100. R–20. F1000 ;
⋅
⋅
⋅
G80 ;
Units of F
Metric input Inch input Remarks
G98 1 mm/min 0.01 inch/min A fractional value
can be specified.
G99 0.0001 mm/ rev 0.000001 inch/rev A fractional value
can be specified.
NOTE
1 G98 and G99 are modal G codes. Upon power–up, G99
(feed per rotation mode) is set.
2 Even in feed per rotation mode, a pulse distribution
command is converted to a feed per minute command.
Thus, feed per rotation mode does not strictly implement
feed per rotation. Accordingly, even if the spindle stops for
some reason, the tapping axis (Z–axis or X–axis) does not
stop.
Rigid tapping in feed per
rotation mode