Thread Undercuts (Cycle940) - Siemens SINUMERIK 840D sl Turning Operating Manual

Programming technology functions (cycles)
10.2 Rotate
Parameters
X1
Z1
VX
* Unit of feedrate as programmed before the cycle call
10.2.5

Thread undercuts (CYCLE940)

Function
The "Thread undercut DIN" or "Thread undercut" cycle is used to program thread undercuts to
DIN 76 for workpieces with a metric ISO thread, or freely definable thread undercuts.
Approach/retraction
1. The tool first moves to the starting point calculated internally in the cycle at rapid traverse.
2. The first cut is made at the machining feedrate, starting from the flank and traveling along
the shape of the thread undercut as far as the safety distance.
3. The tool moves to the next starting position at rapid traverse.
4. Steps 2 and 3 are repeated until the thread undercut is finished.
5. The tool moves back to the starting point at rapid traverse.
During finishing, the tool travels as far as cross-feed VX.
Procedure
414
Description
Allowance in X ∅ (abs) or allowance in X (inc)
Allowance in Z (abs) or allowance in Z (inc) – (for undercut form F only)
Cross feed ∅ (abs) or cross feed (inc)
1. The part program or ShopTurn program to be processed has been cre‐
ated and you are in the editor.
2. Press the "Turning" softkey.
3. Press the "Undercut" softkey.
4. Press the "Thread undercut DIN" softkey.
The "Thread Undercut (DIN 76)" input window opens.
- OR -
Press the "Thread undercut" softkey.
The "Thread Undercut" input window opens.
Operating Manual, 06/2019, A5E44903486B AB
Unit
mm
mm
mm
Turning