Pilot Drilling (Cycle 21, Din/Iso: G121); Cycle Run - HEIDENHAIN TNC 640 User Manual

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7.5 PILOT DRILLING (Cycle 21, DIN/ISO:
G121)

Cycle run

You use Cycle 21 PILOT DRILLING if you subsequently do not use
a center-cut end mill (ISO 1641) for clearing out your contour. This
cycle drills a hole in the area that is to be roughed out with a cycle
such as Cycle 22. Cycle 21 takes the allowance for side and the
allowance for floor as well as the radius of the rough-out tool into
account for the cutter infeed points. The cutter infeed points also
serve as starting points for roughing.
Before calling Cycle 21 you need to program two further cycles:
Cycle 14 CONTOUR
PILOT DRILLING in order to determine the drilling position in
the plane
Cycle 20 CONTOUR
DRILLING in order to determine parameters such as hole depth
and set-up clearance
Cycle run:
1 The TNC first positions the tool in the plane (the position
results from the contour you have defined with Cycle 14 or SEL
CONTOUR, and from the rough-out tool data).
2 The tool then moves at rapid traverse FMAX to the set-up
clearance. (Define the set-up clearance in Cycle 20 CONTOUR
DATA).
3 The tool drills from the current position to the first plunging
depth at the programmed feed rate F.
4 Then the tool retracts at rapid traverse FMAX to the starting
position and advances again to the first plunging depth minus
the advanced stop distance t.
5 The advanced stop distance is automatically calculated by the
control:
At a total hole depth up to 30 mm: t = 0.6 mm
At a total hole depth exceeding 30 mm: t = hole depth / 50
Maximum advanced stop distance: 7 mm
6 The tool then advances with another infeed at the programmed
feed rate F.
7 The TNC repeats this process (1 to 4) until the programmed
total hole depth is reached. The finishing allowance for floor is
taken into account.
8 Finally, the tool retracts in the tool axis to the clearance
height or to the position last programmed before the cycle.
This depends on the parameter ConfigDatum, CfgGeoCycle,
posAfterContPocket.
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Fixed Cycles: Contour Pocket | PILOT DRILLING (Cycle 21, DIN/ISO: G121)
or SEL CONTOUR—needed by Cycle 21
DATA—needed by Cycle 21 PILOT
HEIDENHAIN | User's manual for cycle programming | 10/2017