HEIDENHAIN ND 522 - Manual (Page 12)

12 I Operating Instructions
I -
1
Fu
ndamentals
of
Positioning
I - 1 Fundamentals of Positioning
Datums
The workpiece drawing identifies a certain point on the workpiece
(usually a corner) as the absolute datum, and perhaps one, or more
other points as relative datums.
The datum setting procedure establishes these points as the origin of
the absolute, or relative coordinate systems. The workpiece, which is
aligned with the machine axes, is moved to a certain position relative
to the tool, and the display is set either to zero, or to another
appropriate value (e.g., to compensate for tool radius).
Actual Position, Nominal Position, and Distance-
To-Go
The position of the tool at any given moment is called the actual
position , 1 while the position that the tool is to move to S is called the
nominal position . The distance from the nominal position to the
actual position R , is called the distance-to-go (Incremental).