HEIDENHAIN TNC 306 Technical Manual - Manual (Page 161)

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TNC 406/TNC 306 4 Gap control 4-61
4.5 Free run and spark-out
If the distance between the electrode and workpiece has become so large that the gap signal has
reached 5 V, the generator can transmit a free run signal through a PLC input to the control. This can
be used to set Marker M2616 for "free run during erosion ."
When the programmed position has been reached for the first time (WTG=0) Marker M2783 is set
by the NC. The electrode remains in this position until Marker M2616 is set, and the time in machine
parameter MP2110 has expired. Then the next NC block will be executed.
Spark out in a disk cycle see chapter 6.7.3.
MP2060 Feed rate for infeed when eroding (M2620 is set)
Entry range: 1 to 500 [mm/min]
MP2110 Delay of signal for "spark-out is completed" (marker M2616)
Entry range: 0.1 to 99.9 [s]
Set Reset
M2616 Free run during erosion or spark-out is completed PLC PLC
M2783 End of eroding path reached (WTG = 0) NC NC
M2620 Feed rate from MP2060 becomes active
(input characteristic then has no effect) PLC PLC
D388 Current way to go (WTG)
4.6 Flushing the gap
To make it possible to flush the erosion gap, the electrode can be automatically and cyclically lifted
away from the workpiece and returned again. This "auto jump" distance must be entered in the
Doubleword D730 and the erosion time in Doubleword D734. The cyclic movement for flushing is
started by Strobe Marker M2621. Marker M2780 is set during the up-and-down motion, Marker
M2784 is set only during downward motion, and Marker M2781 is set when the return point has
been reached. Machine Parameter MP2051 defines a distance to the last eroded position up to
which the electrode moved at the feed rate from MP1090 or MP2060, or from the NC program.
From this point on the characteristic curve is active again.
MP2051 Distance to the last eroded position during reapproach
Entry value: 1 to 500 [µm]
Set Reset
M2621 Strobe marker for gap flushing PLC PLC
D756 Auto jump distance during flushing