Siemens SINUMERIK 808D ADVANCED Programming And Operating Manual page 137

DTB (dwell time)
The dwell time must be programmed in seconds. When tapping blind holes, it is recommended that you omit the dwell time.
SDAC (direction of rotation after end of cycle)
Under SDAC, the direction of rotation after end of cycle is programmed.
For tapping, the direction is changed automatically by the cycle.
MPIT and PIT (thread lead as a thread size and as a value)
The value for the thread lead can be defined either as the thread size (for metric threads between M3 and M48 only) or as a
value (distance from one thread turn to the next as a numerical value). Any parameters not required are omitted in the call or
assigned the value zero.
RH or LH threads are defined by the sign of the lead parameters:
● Positive value → right (same as M3)
● Negative value → left (same as M4)
If the two lead parameters have conflicting values, alarm 61001 "Thread lead wrong" is generated by the cycle and cycle
execution is aborted.
POSS (spindle position)
Before tapping, the spindle is stopped with orientation in the cycle by using the command SPOS and switched to position
control.
The spindle position for this spindle stop is programmed under POSS.
SST (speed)
Parameter SST contains the spindle speed for the tapping block with G331.
SST1 (retraction speed)
The speed for retraction from the tapped hole is programmed under SST1.
If this parameter is assigned the value zero, retraction is carried out at the speed programmed under SST.
AXN (tool axis)
The identifiers have the following meanings:
AXN=1
1st axis of the current plane
AXN=2
2nd axis of the current plane
AXN=3
3rd axis of the current plane
For example, to machine a center hole (in Z) in the G17 plane, you program:
G17
AXN=3
Deep-hole tapping: VARI, DAM, VRT
With the VARI parameter, it is possible to distinguish between simple tapping (VARI = 0) and deep-hole tapping (VARI ≠ 0).
In conjunction with deep-hole tapping, it is possible to choose between chip breaking (retraction by variable distance from
current drilling depth, parameter VRT, VARI = 1) and chip removal (withdrawal from reference plane VARI = 2). These
functions work analogously to the normal deep-hole drilling cycle CYCLE83.
The incremental drilling depth for one pass is specified via parameter DAM. The cycle internally calculates the intermediate
depth as follows:
● The programmed incremental drilling depth is executed in each step until the rest up to the final drilling depth is less than
(<) 2 x DAM
● The remaining drilling depth is halved and executed in two steps. Thus, the minimum drilling depth is not smaller than
DAM / 2.
Note
The direction of rotation when tapping in the cycle is always reversed automatically.
Programming and Operating Manual (Milling)
6FC5398-4DP10-0BA1, 01/2014
137