Siemens Sinumerik 840D sl Programming Manual page 129

With G41 activated (machining direction to the left of the contour) the tool vertically moves
away from the contour.
Reference plane for defining the traversing direction for LFTXT
At the point of application of the tool to the programmed contour, the tool is clamped at a
plane which is used as a reference for specifying the liftoff movement with the corresponding
code number.
The reference plane is derived from the longitudinal tool axis (infeed direction) and a vector
positioned perpendicular to this axis and perpendicular to the tangent at the point of
application of the tool.
Job planning
Programming Manual, 02/2011, 6FC5398-2BP40-1BA0
Flexible NC programming
1.14 Interrupt routine (ASUB)
129