HEIDENHAIN TNC 426, User Manual

Page: 262 / 502

236 8 Programming: Cycles
8.3 Cy
cles f
o
r Dr
illing, T
a
pping and Thr
ead Milling
Danger of collision
Always program the same algebraic sign for the infeeds:
Cycles comprise several sequences of operation that are
independent of each other. The order of precedence
according to which the work direction is determined is
described with the individual cycles. If you want to repeat
specific machining operation of a cycle, for example with
only the countersinking process, enter 0 for the thread
depth. The work direction will then be determined from
the countersinking depth.
Procedure in the case of a tool break!
If a tool break occurs during thread cutting, stop the
program run, change to the Positioning with MDI
operating mode and move the tool in a linear path to the
hole center. You can then retract the tool in the infeed axis
and replace it.
The TNC references the programmed feed rate during
thread milling to the tool cutting edge. Since the TNC,
however, always displays the feed rate relative to the path
of the tool tip, the displayed value does not match the
programmed value.
The machining direction of the thread changes if you
execute a thread milling cycle in connection with Cycle 8
MIRRORING with only one axis.