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. There are a number of approaches for successfully detecting and preventing collisions in advance. If the right method is used, undesired downtime can be almost completely eliminated.
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 and crashes, collisions should be detected and prevented before the actual machining. There are two different competing solutions offered by CAD/CAM and simulation software providers Both methods use digital twins of the real manufacturing environment.
Method 1: Machine-independent NC programming in the CAM system and verification of the NC code using additional simulation software.
In this approach, the NC program is first generated in the CAM environment – independent of the machine, tool and clamping device models (digital twins) (1). Only then are the data supplemented with the machine, tool and clamping device information – either before or after NC output, depending on the system (2). The CAM programmer or the machine operator then uses a separate simulation software to verify the NC code.
If no collisions are detected, the NC program is transferred to production (5).
In the event of collisions or other problems, there are two options: The NC code can be corrected manually and then simulated again (if the NC program is generated again later, for example due to changes in parts, it must be corrected and simulated again) (4a). For larger corrections, the error is corrected in the CAM environment (4b). This NC program also has to be verified again in the simulation software to ensure that the correction was successful (4c).
Collisions that the CAM program detects can be prevented with automated collision avoidance strategies that can be integrated in NC templates. 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.