HEIDENHAIN TNC 320 (340 551-02) - Manual (Page 174)

174 7 Programming: Miscellaneous Functions
7.
4 Miscellaneous F
u
nctions f
o
r Cont
our
ing Beha
vior
Retraction from the contour in the tool-axis
direction: M140
Standard behavior
In the program run modes, the TNC moves the tool as defined in the
part program.
Behavior with M104
With M140 MB (move back) you can enter a path in the direction of
the tool axis for departure from the contour.
Input
If you enter M140 in a positioning block, the TNC continues the dialog
and asks for the desired path of tool departure from the contour. Enter
the requested path that the tool should follow when departing the
contour, or press the MAX soft key to move to the limit of the traverse
range.
In addition, you can program the feed rate at which the tool traverses
the entered path. If you do not enter a feed rate, the TNC moves the
tool along the entered path at rapid traverse.
Effect
M140 is effective only in the block in which it is programmed.
M140 becomes effective at the start of the block.
Example NC blocks
Block 250: Retract the tool 50 mm from the contour.
Block 251: Move the tool to the limit of the traverse range.
250 L X+0 Y+38.5 F125 M140 MB 50 F750
251 L X+0 Y+38.5 F125 M140 MB MAX
With M140 MB MAX you can only retract in positive direction.