HEIDENHAIN ND 287 User Manual - Manual (Page 18)

18
I Working with the ND 287 position display unit
I – 2 F
undamentals of positioning
Absolute workpiece positions
Each position on the workpiece is uniquely identified by its absolute
coordinates (see Fig. I.5).
Example : Absolute coordinates of position 1 : Z = 20 mm
If you are drilling or milling a workpiece according to a workpiece
drawing with absolute coordinates, you are moving the tool or length
gauge to the value of the coordinates.
Incremental workpiece positions
A position can also be referenced to the preceding nominal position.
For this, the relative datum must be set to the preceding nominal
position. Such coordinates are referred to as incremental
coordinates
(increment = increase). They are also called incremental
or chain dimensions (since the positions are defined as a chain of
dimensions). Incremental coordinates are identified by a preceding I.
Example:
Incremental coordinate of position
3
referenced to position
2
see Fig. I.6.
Absolute coordinate of position 2 : Z = 10 mm
Incremental coordinates of position 3 : IZ = 10 mm
If you are drilling or milling a workpiece according to a workpiece
drawing with incremental coordinates, you are moving the tool or
length gauge by the value of the coordinates.
Fig. I.5 Position
1:
definition through absolute
coordinates
0
20 1
Fig. I.6 Position 3: definition through incremental
coordinates
0
10
10
2
3