HEIDENHAIN TNC 620 (340 56x-02) Cycle programming - Manual (Page 178)

178 Fixed Cycles: Contour Pocket
7.
5 PIL
O
T DRILLING (Cy
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le 21, DIN/
ISO: G121, A
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7.5 PILOT DRILLING (Cycle 21,
DIN/ISO: G121, Advanced
Programming Features
Software Option)
Cycle run
1 The tool drills from the current position to the first plunging depth
at the programmed feed rate F.
2 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.
3 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
4 The tool then advances with another infeed at the programmed
feed rate F.
5 The TNC repeats this process (1 to 4) until the programmed depth
is reached.
6 After a dwell time at the hole bottom, the tool is returned to the
starting position at rapid traverse FMAX for chip breaking.
Application
Cycle 21 is for PILOT DRILLING of the cutter infeed points. It accounts
for the allowance for side and the allowance for floor as well as the
radius of the rough-out tool. The cutter infeed points also serve as
starting points for roughing.
Please note while programming:
Before programming, note the following:
When calculating the infeed points, the TNC does not
account for the delta value DR programmed in a TOOL CALL
block.
In narrow areas, the TNC may not be able to carry out pilot
drilling with a tool that is larger than the rough-out tool.