Abstract: The invention relates to a system for a method for controlling a machine tool with at least one replaceable tool and a workpiece, especially a mill blank, and for a method for machining the workpiece, which machine tool comprises a robot arm movable along at least 2, especially at least 3 space axes in an area of motion, which carries and moves at least one workpiece, eventually via a workpiece holder, with a control unit for controlling the machine tool. The machine tool (52) includes a sensor (46), especially a space-fixed optical sensor located thereon or associated thereto, and the detection range (42) of which overlaps the area of motion at least partially for detection of a code on the machine tool.