Siemens SINUMERIK 840Di sl Programming Manual page 383

CDOF helps prevent the incorrect detection of bottlenecks, e.g., due to missing information,
which is not available in the NC program.
Machine manufacturer
The number of NC blocks monitored can be defined in the machine data (see machine
manufacturer).
Example of milling on the center-point path with standard tools
The NC program defines the center-point path of a standard tool. The contour for a tool
currently in use results in an undersize, which is shown on an unrealistically large scale
solely to illustrate the geometric conditions. The following description is based on the simple
assumption that the control can only "see" three blocks.
Since an intersection exists only between the offset curves of the two blocks N10 and N40,
the two blocks N20 and N30 would have to be omitted. In this instance, the control is still not
aware of block N40 if N10 must be processed subsequently. Only a single block can
therefore be omitted.
When CDOF2 is active, the compensatory motion shown in the diagram is executed and not
halted. In this situation, an active CDOF or CDON would generate an alarm.
Identifying critical machining situations
The following are some examples of critical machining situations, which can be detected by
the control and compensated for by modifying the tool paths.
In order to prevent program stops, you should always select the tool with the widest radius
from all of the tools used when testing the program.
In each of the following examples a tool with too wide a radius was selected for machining
the contour.
Fundamentals
Programming Manual, 11/2006, 6FC5398-1BP10-2BA0
8.12 Collision monitoring (CDON, CDOF, CDOF2)
Tool offsets
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