Siemens Sinumerik 840D sl Programming Manual page 79

Figure 4-5
Explanations
On using the G73 cycle, the retraction motion takes place after the drilling with rapid
traverse. The safety clearance can be specified with GUD _ZSFR[0]. The retraction amount
from chip breaking (d) is defined with GUD _ZSFR[1]:
_ZSFR[1] > 0 Retraction amount as input
_ZSFR[1] v 0 Retraction amount in chip breaking is always 1 mm
The in-feed takes place by using the cutting depth for each cutting Q which is incremented
with the retraction amount d as second in-feed.
A rapid drilling infeed results with this drilling cycle. Chip removal takes place through the
retraction motion.
ISO Milling
Programming Manual, 06/09, 6FC5398-7BP10-1BA0
Deep hole drilling cycle with chip breakage (G73)
Additional functions
4.1 Program supporting functions
79