HEIDENHAIN ND 780 - Handbuch (Seite 141)

ND 780
17
I - 1 F
undamentals of P
o
sitioning
Absolute Workpiece Positions
Each position on the workpiece is uniquely identified by its absolute
coordinates.
Absolute coordinates of position
1 :
X = 20 mm
Y = 10 mm
Z = 15 mm
When drilling, or milling a workpiece according to a workpiece drawing
with absolute coordinates, the tool is moving to the value of the
coordinates.
Incremental Workpiece Positions
A position can also be referenced to the preceding nominal position.
In this case the relative datum is always the last 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 designated with the prefix I.
Example: Incremental coordinates of position 3 referenced to
position 2 .
Absolute coordinates of position 2 :
X = 20 mm
Y = 10 mm
Z = 15 mm
Incremental coordinates of position
3 :
I X = 10 mm
I Y = 10 mm
I Z = -15 mm
When drilling or milling a workpiece according to a drawing with
incremental coordinates, the tool is moving by the value of the
coordinates.