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A major problem with automated inspection systems is discrimination of defects, which are not detrimental to final quality from those that are. VAI SIAS (formerly MATRA) uses advanced techniques to screen out harmless anomalies and is achieving a 96% success rate in defect detection on a hot strip mill in France.
Two years ago, YAl SIAS received final acceptance for its first hot rolling mill automatic surface inspection (ASI) system from Sollac Atlantique (Dunkerque Works), a company of the group Arcelor. With several such installations in operation today, VAI SIAS 100% coverage offers a breakthrough in Quality Management on strip mills and coating lines. For the first time, the system can be fully and flawlessly integrated into the decision-making process of the mill's production department.
After introducing the technical highlights of the installation, this paper focuses on the main objectives that were targeted by the customer in this first project and describes how VAI SIAS designed and developed an industrial quality control system.
PROJECT BACKGROUND
By the time it was decided to invest in hot-strip inspection technology, Arcelor (then Usinor) had acquired highly significant experience in the application of automatic surface inspection for steel strip and all of the group's hot- dip galvanising lines producing automobile products were - and still are - equipped with such ASI systems - all supplied by VAI SIAS, at that time known as MATRA.
The systems are not simple gauges that generate a map of each coil where defects are represented. The measurement provided in real time by the VAI SIAS equipment is so precise and reliable that it can enable a dramatic reduction (>90% for some products) of production sent through the long and costly visual re -inspection process. More importantly, this result is achieved without intervention of an expert inspector or any other additional procedure. Today the quality inspector alone is instantly capable of making a decision on delivery of the coil that has just been produced. As the need for ASI technology started to impact on the upstream process and more specifically on the hot-mill, nothing other than the same efficiency was expected.
The benefits of the earlier detection of surface defects are clear:
- Avoiding 'defect crisis' by early identification of the defect's origin...