HEIDENHAIN TNC 426, User Manual

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274 8 Programming: Cycles
8.4 Cy
cles f
o
r milling poc
k
e
ts, st
uds and slots
CIRCULAR SLOT (oblong hole) with
reciprocating plunge-cut (Cycle 211)
Roughing process
1 At rapid traverse, the TNC positions the tool in the tool axis to the
2nd set-up clearance and subsequently to the center of the right
circle. From there, the tool is positioned to the programmed set-up
clearance above the workpiece surface.
2 The tool moves at the milling feed rate to the workpiece surface.
From there, the cutter advances — plunge-cutting obliquely into
the material — to the other end of the slot.
3 The tool then moves at a downward angle back to the starting
point, again with oblique plunge-cutting. This process (2 to 3) is
repeated until the programmed milling depth is reached.
4 At the milling depth, the TNC moves the tool for the purpose of
face milling to the other end of the slot.
Finishing process
5 The TNC advances the tool from the slot center tangentially to the
contour of the finished part. The tool subsequently climb mills the
contour (with M3), and if so entered, in more than one infeed. The
starting point for the finishing process is the center of the right
circle.
6 When the tool reaches the end of the contour, it departs the
contour tangentially.
7 At the end of the cycle, the tool is retracted in rapid traverse FMAX
to set-up clearance and — if programmed — to the 2nd set-up
clearance.
X
Z
Q200
Q207
Q202
Q203
Q204
Q201
X
Y
Q217
Q216
Q248
Q245
Q219
Q244
Before programming, note the following:
The TNC automatically pre-positions the tool in the tool
axis and working plane.
During roughing the tool plunges into the material with a
helical sideward reciprocating motion from one end of the
slot to the other. Pilot drilling is therefore unnecessary.
The algebraic sign for the cycle parameter DEPTH
determines the working direction. If you program DEPTH
= 0, the cycle will not be executed.
The cutter diameter must not be larger than the slot width
and not smaller than a third of the slot width.
The cutter diameter must be smaller than half the slot
length. The TNC otherwise cannot execute this cycle.