HEIDENHAIN TNC 620 User Manual page 281

Testing and running | Program run
Caution: Danger to the tool and workpiece!
A power failure during the machining operation can cause
uncontrolled "coasting" or braking of the axes. In addition, if
the tool was in effect prior to the power failure, then the axes
cannot be referenced after the control has been restarted.
For non-referenced axes, the control takes over the last saved
axis values as the current position, which can deviate from the
actual position. Thus, subsequent traverse movements do not
correspond to the movements prior to the power failure. If the tool
is still in effect during the traverse movements, then the tool and
the workpiece can sustain damage through tension!
Use a low feed rate
Please keep in mind that the traverse range monitoring is not
available for non-referenced axes
Example
The power failed while a thread-cutting cycle was being performed in
the tilted working plane. You have to retract the tap:
Switch on the power supply for control and machine
The control starts the operating system. This process may take
several minutes.
The control will then display the Power interrupted message in
the screen header.
Activate the Retraction mode: Press the
RETRACT soft key
The control displays the message Retraction
selected.
Confirm the power interruption: Press the CE key
The control compiles the PLC program.
Switch on the machine control voltage
The control checks the functioning of the
EMERGENCY STOP circuit. If there is at least one
non-referenced axis, you will have to compare
the displayed position values with the actual
axis values and confirm that they are correct. If
required, follow the dialog.
Check the preselected traverse mode: If required, select THREAD
Check the preselected thread pitch: If required, enter the thread
pitch
Check the preselected direction of rotation: if needed, select the
turning direction of the thread
Right-handed thread: the main spindle turns clockwise when
moving into the workpiece, counter-clockwise when retracting
from it; left-handed thread: main spindle turns counter-clockwise
when moving into the workpiece and clockwise when retracting
from it
HEIDENHAIN | TNC 620 | User's Manual for Setup, Testing and Running NC Programs | 01/2022
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