The Practical Application of Automatic Inspection Instrumentation to Cold Rolled Steel Strip

The limitations of visual inspection of cold rolled steel strip for surface imperfections are reviewed. It is argued that, due to the complex nature of steel imperfection identification, interim automatic inspection solutions will still have to depend upon the judgment capabilities of human inspectors. This principle is incorporated into a laser based automatic inspection system for cold rolled strip. The speed of the automatic inspection equipment is employed as an aid to enhance the performance and versatility of human visual inspection. In the described system, automatic inspection data are formatted into computer generated real-time visual displays. These displays give the inspectors warnings of upcoming imperfections that require their interpretation and judgment. Extensive on-line data are examined to show the limitations of current visual and automatic inspection performance as a function of speed and defect type. The practical applications experience gained by inspecting a variety of steel strip finishes with this system is used to outline areas for future technical development, and to comment on its applicability to various other steel mill processing operations.