Limitations of the integrated postprocessing and simulation program

Modelling the material removal:
The actual simulation program does not simulate the material removal process yet. Consequently the
workpiece geometry is not updated during the execution of the milling path. As a result the simulation
program can only perform a collision test on the geometry of either the blank part or the final workpiece. For
most applications this will be sufficient. Simulation using the blank part is safe and the absence of small
details in this geometry fastens the execution of the simulation run. However if a lot off the material is cut to
produce the final shape, the program could report collisions of the tool holder or the machine structure with
bulk material already cut by the preceding part of the tool path.

Automatic modification of the tool path:

Presently it is impossible to inform the CAD/CAM system about a collision in order to force the CAM module to automatically correct the cutter inclination (e.g. lead angle) and to eliminate the collision. To achieve this goal one could integrate the CAM module, the NC-postprocessor and the simulation program. However generating and verifying the NC program depends on the knowledge of the clamping position and the tool length. Therefore combining the tool path generation, the post-processing and the simulation is only useful if both the clamping position and the length of all cutters are known in advance. The CAM module could send each cutter location to the NC-postprocessor. The NC-postprocessor calculates the movement made by the NC machine. The simulation software automatically verifies this movement. If a collision occurs which the  NCpostprocessor can not avoid, then the CAM module becomes informed. The CAM system in its turn applies collision avoidance methods considering the type of collision. Again implementing a general solution able to handle all situations would be very complex. However for certain groups of workpieces, machined on a specific milling machine, one could specify a number of collision avoidance rules that give the CAM module the ability to avoid most collisions.