Coding and identifying plate-type workpieces

A metal workpiece working machine comprising:

• an eddy-current sensor configured to detect eddy-current signals;
• an evaluation device configured to extract information from the detected eddy-current signals;
• a storage device configured to store at least one of the extracted information or the detected eddy-current signals;
• and
• a controller configured to control operations comprising:
• coding the workpiece by producing a code with a local modification in a material structure of a base material of the workpiece within a coding region;
• reading out the code by performing an eddy-current measurement of a local distribution of at least one of an electrical conductivity or a permeability of the base material of the workpiece by the eddy-current sensor along a reading-out section in a reading region, wherein the reading region at least partially comprises the coding region, wherein an eddy current signal calibrated to a distance between the eddy-current sensor and a surface of the base material of the workpiece is determined for the reading out of the code, and wherein the determined calibrated eddy current signal in the reading region is independent from the distance and is associated with the read-out code;
• storing the read-out code in the storage device;
• repeating the reading out of the code by repeating the eddy-current measurement;
• and
• identifying the workpiece by comparing the stored read-out code in the storage device and the repeated read-out code.