SPC - Statistical Process Control
The purpose of the built-in SPC function is to give the operator or quality control staff data that let them judge the stability and capability of the assembly process according to standard SPC rules.
By configuring the SPC function within the controller, it is possible to simplify and do the work directly on the controller without the need of external software. The charts are generated on the controller.
Since it is possible to use program monitors within the controller as a SPC variable, it is necessary to specify that only variables controlled by the controller show the performance of the controller system. Other variables show mainly results from other processes. For example, if a torque value is applied to a joint, then SPC of the final torque value and the related results - such as Cp and Cpk - show the performance of the tool and the controller on that joint.
Statistical calculations are based on old data stored in the controller.
Statistical calculations are done on a Virtual Station level, depending on the tightening program selected and used for that specific Virtual Station.
