Siemens SINUMERIK 840D sl Programming Manual page 818

Glossary
Exact stop
When an exact stop statement is programmed, the position specified in a block is
approached exactly and, if necessary, very slowly. To reduce the approach time, → exact
stop limits are defined for rapid traverse and feed.
Exact stop limit
When all path axes reach their exact stop limits, the controller responds as if it had reached
its precise destination point. A block advance of the → part program occurs.
External zero offset
Zero offset specified by the → PLC.
Fast retraction from the contour
When an interrupt occurs, a motion can be initiated via the CNC machining program,
enabling the tool to be quickly retracted from the workpiece contour that is currently being
machined. The retraction angle and the distance retracted can also be parameterized. An
interrupt routine can also be executed following the fast retraction.
Feed override
The programmed velocity is overriden by the current velocity setting made via the → machine
control panel or from the → PLC (0 to 200%). The feedrate can also be corrected by a
programmable percentage factor (1 to 200%) in the machining program.
Finished-part contour
Contour of the finished workpiece. See → Raw part.
Fixed machine point
Point that is uniquely defined by the machine tool, e.g. machine reference point.
Fixed-point approach
Machine tools can approach fixed points such as a tool change point, loading point, pallet
change point, etc. in a defined way. The coordinates of these points are stored in the
controller. The controller moves the relevant axes in → rapid traverse, whenever possible.
Frame
A frame is an arithmetic rule that transforms one Cartesian coordinate system into another
Cartesian coordinate system. A frame contains the following components: → zero offset,
→ rotation, → scaling, → mirroring.
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Programming Manual, 03/2013, 6FC5398-2BP40-3BA1
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