Siemens SINUMERIK User Manual page 212

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 ignored directly.
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.
PIT (thread pitch) and PITA (unit of thread pitch)
The thread lead is an axis-parallel value and is specified without sign. The unit of it is defined in parameter PITA.
PITA = 1 pitch in mm/revolution
= 2 pitch in threads per inch (TPI)
VARI (machining type)
By using the VARI parameter, it is defined whether external or internal machining will be carried out and which technology
will be used with regard to the infeed when roughing. The VARI parameter can assume values between 1 and 4 with the
following meaning:
Value Ext./int.
300101 O
300102 I
300103 O
300104 I
If a different value is programmed for the VARI parameter, the cycle is aborted after output of alarm 61002 "Machining type
defined incorrectly".
_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 system of units, inch or metric.
PSYS (the last parameter displayed on the screen)
This parameter specifies the selection of longitudinal thread, face thread or taper thread.
0 = longitudinal thread:
212
Const. Infeed/const. cutting cross-section
Constant infeed
Constant infeed
Constant cutting cross-section
Constant cutting cross-section
Programming and Operating Manual (Turning)
01/2017