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Expanded Portfolio of Products for Surface Inspection Significantly Benefits the Steel Manufacturing Industry


Unique Innovations make the Inspection of Slabs and thick Plates posssible

Aachen/Germany – November 2009. ISRA PARSYTEC, the world’s leading supplier of surface inspection systems for web products, introduces a whole new dimension in efficient flat steel production: The latest innovations now make the inspection of slabs and thick plates possible. By being able to inspect slabs, steel manufacturers can discover defects relevant to production at a very early stage and thus save material and time.

Today, manufactures of high-quality steels are able to use surface inspection systems in most processing steps of flat steel production, such as hot rolling, pickling, cold rolling, galvanizing, etc. to automatically inspect intermediate and end products for defects. However, for the upstream processes and thus for slabs, up until now they have not had the technical capabilities to do so.

Saving production time and effort and material
Yet, especially the surface of slabs can provide important information relating to major defects: One example – longitudinal and transverse cracks are often covered by the following hot rolling process and do not become visible until much later during the manufacturing of flat steel. By this time, a significant amount of time and effort has been wasted needlessly in the finishing process. If these kinds of defects could already be detected early on, that is on the slab itself, the manufacturer would save not only production time and effort, but also material and as a result could schedule repair measures in due time.

The reason why slabs cannot be inspected today, or if at all, only visually and thus very inefficiently, has to do with the difficult underlying conditions involved in automatic inspection: The slab surface, because of its material, is often characterized by a strongly defined structure. Simple, contrast-based defect detection methods can therefore hardly ever be applied in a manner that would make the use of such worthwhile. As soon as the slab is released from the casting unit, the surface is scaled. This results not only in defects being covered, but also leads to surface structures, which can easily be mistaken for other specific defects. Moreover, some defects in the form of cracks are not formed until the slab cools down. They may already be present in the hot slab, but they are not visible. On the other hand, inspecting the cooled slab would then slow down the production process and drastically reduce energy efficiency. Plus, ambient conditions in effect for continuous casting, casting roller or hot rolling units put high demands on the quality of the technical equipment needed in the inspection system, which up until now were either unable to be satisfied at all or only at a huge expense.

Based on research undertaken by ISRA PARSYTEC over the course of several years, a range of products for slab inspection was developed, which solved the problems mentioned above. The basis of the products is the espresso inspection systems. Today, these systems are already being used to deal with a number of important applications. Also assisting in their realization is an extensive selection of sensors. However, the most critical aspect of these systems is the software intelligence. In it is the knowledge acquired from more than 300 installations within the flat steel industry. The new inspection systems are constantly being developed further.

With the Instant Classifier, an intelligent classification tool that is preset in advance, 80% of the defects are ferreted out immediately based on an extensive catalog of defects. Only around 20% of defects relate specifically to the equipment itself and must be taught in. This significantly speeds up the initial set-up. Because the software algorithms are highly flexible, it is even possible to be able to clearly distinguish between defects and non-defects on strongly defined structures. During the defect classification process, the system can make use of 800 different characteristics – half of which are texture characteristics. During the detection phase, the system adjusts to the sensitivity of the texture. As a result, the inspection systems can, with a high level of accuracy, distinguish between defects and other structures, for example the accumulation of scales.

What has been found to be especially promising is the inspection of hot slabs after the scale washing process and before the rolling stands, both in hot rolling lines as well as in combined continuous casting and rolling equipment, as can already be seen in initial applications by steel manufacturer. In this case, the surface is lightly scaled, the ambient conditions are difficult, but they can be managed and the inspection results of slab and hot strips can be correlated immediately. 

The self-radiation of red hot slabs is suppressed with special optical filters. A special enclosure technology protects the hardware in use from heat and steam. A cleaning blower eliminates – if necessary – any water left on the slab before the inspection takes place. The inspection software takes the linear expansion of the material into account in the rolling stands, thus making a position accurate inspection of, for example, crack defects on the slab as well as shell defects on the hot strip possible. In the near future, there will be another solution available that uses 3D inspection technology, with which it will be possible to distinguish crack defects even more reliably from dents for example. 

Thick plate inspection systems already proven in day-to-day operations
With the introduction of thick plate inspection technology, ISRA PARSYTEC has successfully unlocked yet another complex field in the quality assurance of flat steel products. Even though thick plates run through a production process that is very similar to the hot strip process, they show distributions and dimensions of surface defects that are entirely different. Even the accumulation of scales is generally significantly higher. 

The range of products offered by ISRA PARSYTEC for thick plate inspection makes it possible to inspect both hot thick plates, providing information fast about the produced quality so that decisions can be made quickly on the possible further use, as well as to inspect cold thick plates for the final delivery evaluation and the ability to make targeted decisions on any repairs that might be necessary. In both applications, marking systems can be integrated so that areas requiring repair can be found easily and their positions can be approached accurately. Numerous steel manufacturers are already benefiting from the thick plate inspection technology offered by ISRA PARSYTEC, for example MMK in Russia, NISCO in China and Columbus Stainless Steel in South Africa. 

The solutions offered by ISRA PARSYTEC greatly assist in the efficient increase of the production to its maximum potential. Quality becomes plannable, processes and production can be optimized systematically.

About the company:
The ISRA VISION PARSYTEC AG is the world's largest vendor of surface inspection systems: Today, all of the top 10 steel producers and 15 of the top 20 paper producers employ its products. With more than 600 installations worldwide, it provides its customers with the most advanced surface inspection system as well as reliable and comprehensive information about the relevant surface defects at all production steps. The innovative EXPERT5i software solutions enables customers to easily create individual surface quality yield management applications while integrating surface quality data with process data. 

The ISRA VISION Gruppe is the world's largest and most capable vendor of surface inspection systems. The systems are used in the glass, banknote paper, paper, plastics, non-woven fabrics, printing and metalworking industries. The ISRA VISION Group is operating globally with its headquarters in Germany (Darmstadt and Aachen) as well as 15 additional subsidiaries worldwide, e.g. in North America, Korea and China.

Annick Welfring
++49 (241) 9696 - 600

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