Description : | Zinc coating is the most effective and widely used process to prevent corrosion and increase the longevity and performance of steel wire. Zinc coating is generally applied to steel wire by hot-dip galvanizing (HDG) process. In this process, the steel wire is passed through a bath of molten liquid zinc or zinc alloy resulting in a protective layer. The final quality of galvanized wire depends on the material surface, zinc adhesion, and uniform coating weight. Proper substrate cleaning and temperature control can govern the first two parameters, but the coating weight is often measured too late in the process to correct. In fact, many producers verify hot-dip zinc coating weight after the coil exits the mill. At this point, if the results are unacceptable the entire coil is downgraded or scrapped. This results wastage of raw materials and production costs. Generally, wiping technologies (Nitrogen wiping for thick coating and Pad wiping for thin coating) are adopted in order to address this issue. Though the Zinc weight control system exists in N2 wiping line but there is no such system is available for Commercial line. Non-existent of inline GI coating weight measurement system makes the producer handicapped to assess the required weight. However, in the pad wiping galvanizing process during production, due to a number of process conditions steel wire coating weight inevitably fluctuates leading to the variation of coating thickness that not only contributes to the instability of the product quality, but also the loss of costly coating raw materials like zinc. The present technology offers a real-time, non-contact industrial sensing system coupled with data processing and feedforward control mechanism that is capable of working in harsh industrial environments while providing immediate feedback on zinc weight during production in both N2 wiping as well as Pad wiping (Commercial) GI lines. |