Siemens SINUMERIK 840D Programming Manual page 158

Milling Cycles
3
3.11 Face milling - CYCLE71
The first path to be milled is always selected so that
the infeed width is exactly _MIDA, and thus no width
exceeds the maximum possible value. The tool
center point thus does not always travel exactly to
the edge (only if _MIDA = mill radius). The
dimension by which the tool traverses outside the
edge always equals
cutter diameter - _MIDA,
even when only 1 surface cut is performed, i.e.
surface width + overrun less than _MIDA. The other
paths for width infeed are calculated internally so as
to produce a uniform path width (<=_MIDA).
• Motion sequence when finishing (VARI=X2):
When finishing, the surface is once milled in the
plane. The finishing allowance for roughing must
also be selected so that the remaining depth can
be machined in one pass with the finishing tool.
After each surface milling pass in the plane, the
tool retracts completely. The retraction travel is
programmed by the parameter _FDP.
• Machining in one direction stops at the finishing
allowance + safety clearance and the next starting
point is reached at rapid traverse.
Roughing in one directions stops when reaching the
calculated infeed depth + safety clearance. The
infeed depth is performed towards the same point as
for roughing.
After finishing has been completed, the tool retracts
from the last position reached to the retraction plane
_RTP.
3-158
Y
Milling during finishing in one direction
(type of machining 22)
SINUMERIK 840D/840Di/810D/FM-NC Programming Guide, Cycles (PGZ) - 04.00 Edition
03.96
12.98
3
X
 Siemens AG 2000 All rights reserved.