Process:
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From the current position, the tool drills at the
entered feed rate to the first pecking depth.
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The tool is then retracted at rapid traverse
(FMAX) and advances again to the first pecking
depth, minus the advanced stop distance t. The
advanced stop distance is calculated automati-
cally by the control:
- Total hole depth up to 30 mm: t = 0.6 mm
- Total hole depth over 30 mm:
t = Total hole depth/50
Maximum advanced stop distance: 7 mm
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The tool advances with another infeed at the
programmed feed rate.
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These steps are repeated until the programmed
total hole depth is reached.
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After a dwell time at the bottom of the hole, the
tool is retracted to the starting position at FMAX
for cutting free.
input data
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SET-UP CLEARANCE (incremental value):
Fig. 8.2: PECKING cycle
Distance between tool tip (starting position) and workpiece surface.
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TOTAL HOLE DEPTH (incremental value):
Distance between workpiece surface and bottom of hole (tip of drill
taper).
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PECKING DEPTH (incremental value):
lnfeed per cut. The TNC moves in one operation to the TOTAL HOLE
DEPTH if:
- PECKING DEPTH and TOTAL HOLE DEPTH are identical
- the PECKING DEPTH is greater than the TOTAL HOLE DEPTH.
The TOTAL HOLE DEPTH does not have to be a multiple of the PECK-
ING DEPTH.
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DWELL TIME IN SECONDS:
Length of time the tool remains at the total hole depth for cutting free.
. FEEDRATEF:
Traversing speed of the tool during drilling.
8-6
TNC 370
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