HEIDENHAIN TNC 320 (340 551-01) - Manual (Page 194)

194 8 Programming: Cycles
8.2 Cy
cles f
o
r Dr
illing,
T
apping and Thr
ead Milling
8 Infeed depth for chip breaking Q257 (incremental
value): Depth at which the TNC carries out chip
breaking. There is no chip breaking if 0 is entered.
8 Retraction rate for chip breaking Q256
(incremental value): Value by which the TNC retracts
the tool during chip breaking.
8 Dwell time at depth Q211: Time in seconds that the
tool remains at the hole bottom.
8 Deepened starting point Q379 (incremental with
respect to the workpiece surface): Starting position of
drilling if a shorter tool has already pilot drilled to a
certain depth. The TNC moves at the feed rate for
pre-positioning
from the set-up clearance to the
deepened starting point.
8 Feed rate for pre-positioning Q253: Traversing
velocity of the tool during positioning from the set-up
clearance to a deepened starting point in mm/min.
Effective only if Q379 is entered not equal to 0.
Example: NC blocks
11 CYCL DEF 205 UNIVERSAL PECKING
Q200=2 ;SET-UP CLEARANCE
Q201=-80 ;DEPTH
Q206=150 ;FEED RATE FOR PLUNGING
Q202=15 ;PLUNGING DEPTH
Q203=+100 ;SURFACE COORDINATE
Q204=50 ;2ND SET-UP CLEARANCE
Q212=0.5 ;DECREMENT
Q205=3 ;MIN. PLUNGING DEPTH
Q258=0.5 ;UPPER ADV STOP DIST
Q259=1 ;LOWER ADV STOP DIST
Q257=5 ;DEPTH FOR CHIP BRKNG
Q256=0.2 ;DIST. FOR CHIP BRKNG
Q211=0.25 ;DWELL TIME AT DEPTH
Q379=7.5 ;STARTING POSITION
Q253=750 ;F PRE-POSITIONING
If you use Q379 to enter a deepened starting point, the
TNC merely changes the starting point of the infeed
movement. Retraction movements are not changed by
the TNC, therefore they are calculated with respect to the
coordinate of the workpiece surface.