Online Measurement of Residual Dirt on Steel Plates by Laser Ablation and Acoustic Detection

Cold rolled steel plate emerges from the manufacturing process with a thin layer of residual dirt that has to be kept under control for two main reasons: it may be indicative of deviations from normal functioning in previous manufacturing stages and it may impair the e ffectiveness of downstream operations such as painting and galvanising. Standard measurements of this residual dirt are based on undependable laboratory sample measurements, outside the production line. A method has been developed that allows online determination of the cleanliness for the whole manufactured steel plate bobbin. Based on this method, the first industrial instrument (Elmes I) has been designed, which is now in operation at the final inspection line of the Siderar plant at Ensenada, Buenos Aires, Argentina. SE / S216