Siemens SINUMERIK 808D ADVANCED Programming And Operating Manual page 180

Value Ext./int.
1 External
2 Internal
3 External
4 Internal
If a different value is programmed for the VARI parameter, the cycle is aborted after output of alarm 61002 "Machining type
defined incorrectly".
NUMTH (number of thread turns)
Use the NUMTH parameter to define the number of thread turns with a multiple-turn thread. For a single-turn thread, the
parameter must be assigned zero or can be dropped completely in the parameter list.
The thread turns are distributed equally over the circumference of the turned part; the first thread turn is determined by the
NSP parameter.
To produce a multiple-turn thread with an asymmetrical arrangement of the thread turns on the circumference, the cycle for
each thread turn must be called when programming the appropriate starting point offset.
_VRT (variable retraction path)
The retraction path can be programmed on the basis of the initial thread diameter in the _VRT parameter. For _VRT = 0
(parameter not programmed), the retraction path is 1 mm. The retraction path is always measured according to the
programmed measuring system, inch or metric.
Programming example: Thread chain
You can use this program to produce a thread chain starting with a cylindrical thread. The infeed is performed vertically to
the thread; neither finishing allowance, nor starting point offset are programmed. Five roughing cuts and one noncut are
performed. The machining type is defined as longitudinal, external, with constant cross-section of cut.
180
Const. Infeed/const. cutting cross-section
Constant infeed
Constant infeed
Constant cutting cross-section
Constant cutting cross-section
Programming and Operating Manual (Turning)
6FC5398-5DP10-0BA2, 06/2015