Machine damage worst-case scenario: A collision between the machine head and the part, the tool and clamping devices or the spindle and machine table can be an expensive mistake. But even if the worst doesn't happen, detecting and preventing potential collisions almost always results in unintended downtime. This doesn’t need to be the case.
On simpler machines, an attentive machine operator can usually visually detect potential collisions and press the emergency stop button in time. However, fast and complex movements make it impossible to manually interrupt machining on modern high-performance machines like turning-milling centers or simultaneous 5-axis machines. These machines are automatically stopped by integrated protective mechanisms in the event of a collision risk. But even if the machine is stopped manually or automatically, the result is the same: The machine is sitting idle.
To prevent machine downtime, collisions should be detected and prevented before the actual machining begins. There are three different competing solutions that are offered by CAD/CAM and simulation software providers. All three models use digital twins of the real manufacturing environment to verify the toolpaths.
Model 1: With this approach, the NC program is first generated in the CAM environment independent of the machine (1). The postprocessed data isn’t supplemented with the information for the relevant machine until NC output (2). The CAM programmer, the production manager or the machine operator then uses a separate simulation application to verify the NC code.
One of two options is used for managing irregularities: The NC code is manually corrected and then simulated again (4a). For larger corrections, the error is corrected in the CAM environment and then the NC program is output again (4b).
If no other collisions are identified, the part can be machined (5).
This comparison of the three variants shows that the third approach – integrated simulation and collision-checking – has many advantages:
Another advantage of the fully integrated solution: Because the CAM programmer has access to all components that are also used in real production right at his or her workstation, comprehensive options are already available for preventing collisions during planning and CAM programming – i.e., even before simulation. This saves even more time. Many errors are corrected before they can become a problem.
Collisions that are detected during calculation of the NC program can be identified and prevented with collision avoidance strategies. The most appropriate strategy depends primarily on the specific component geometry, the machining task and especially the available machine. This knowledge should be stored in NC templates: This means that the CAM programmer only has to select the machine and machining elements. The appropriate collision avoidance strategy – with area reduction, simultaneous 5-axis avoidance milling or indexed machining – is automatically assigned.
In indexed machining, milling areas that can be machined collision-free at the same tilt direction are automatically detected and combined. The corresponding tilt direction is also automatically calculated.
Integrated simulation accounts for all tilt directions, all tool components and the entire machine with all movements and tool changes. This ensures that machining is collision-free for each clamping situation.