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

Programming technology functions (cycles)
8.2 Rotate
Parameters
Position
X0
Z0
X1
Z1
VX
8.2.5

Thread undercuts (CYCLE940)

Function
You can use the "Thread undercut DIN" or "Thread undercut" cycle 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
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.
288
Description
Form F machining position:
Undercut size according to DIN table:
e.g.: F0.6 x 0.3 (undercut form F)
Reference point X ∅
Reference point Z
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)
the shape of the thread undercut as far as the safety distance.
Operating Manual, 07/2010, 6FC5398-8CP40-0BA0
Unit
mm
mm
mm
mm
mm
Turning