The stop position surveillance of the stop bolts is a facility for the workpiece stops on CNC-machining centres.

These stops mostly consist of cylinders, which are pneumatically drawn out for application and drawn back in before the processing.

If a stop is drawn out either accidentally or due to a malfunction, a collision with the milling tool is to be expected for the workpiece processing, as the stops are located on the outer contour

A sensor can be found on every single stop for the stop position surveillance, which registers, whether the bolt has been drawn in completely. The program start for the workpiece processing is only to be released when all sensors report drawn-in stop cylinders and therefore a collision can be excluded.