In order to mark semi-finished products and products reliably, unambiguously and counterfeit-proof, various marking solutions exist on the market. These range from a simple serial number to integrated RFID chips (Radio Frequency IDentification). However, these solutions do not meet the special requirements of metal processing. For example, inks that are often only temperature-stable up to 250 °C prove to be problematic. This means that their use is not possible at the increased workpiece temperatures of up to 1250 °C. The ink is not suitable for use at the higher workpiece temperatures. In addition, the material surface can change during processing, which reduces the contrast between the metal surface and the marking, so that it can no longer be read out. Temperature-stable labels in turn apply too much material and thus interfere with further processing.
In order to guarantee traceability across all processes, Fraunhofer IKTS has developed a robust marking solution based on ceramic phosphors that react to optical excitation by light with distinct luminescence. These materials are very robust: they can withstand high temperatures, are insensitive to chemical influences and can be added to various materials. This makes it possible to introduce the phosphors directly into inks or pastes and print them onto the components. Since only the smallest amounts of material are printed, any influence on the workpiece properties or the adhesion of coatings can be ruled out. The inks and pastes mixed with phosphors are safe and environmentally friendly, so that no further occupational safety measures are necessary. Due to the high contrast between marking and carrier material it is possible to read them out in all lighting situations.