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ThyssenKrupp Nirosta Using RFID technology for Roll Management at Dillenburg
03/31/2011 - ThyssenKrupp Nirosta is now using Radio Frequency Identification, one of the most innovative and fastest-growing identification technologies available, to keep track of its rolls and operational details of its cold rolling mill in Dillinger.
ThyssenKrupp Nirosta is now using one of the most innovative and fastest-growing identification technologies available to keep track of its rolls: Radio Frequency Identification, or RFID. With RFID, data can be read contactlessly and fully automatically over longer distances
and the information can be processed for a wide variety of purposes. The core components of RFID systems are transponders, readers with antennas, and interfaces to the data processing system. The Dillenburg plant uses passive transponders read by radio antennas.
There’s plenty to track at ThyssenKrupp Nirosta’s Dillinger cold rolling mill, including five rolling mills, 2200 rolls and bearings, 4700 storage locations, and 200 to 250 turning, grinding and polishing operations and storage movements each day. And not all the rolls are the same, as some are suitable only for certain stainless steel grades or strip thicknesses. They come in different shapes and, even more challenging, their diameter is changing all the time.
At its Dillenburg plant ThyssenKrupp Nirosta produces 21,000 to 24,000 tonnes per month of stainless steel cold-rolled strip with premium-quality finishes, used for example in prestigious building facades and high-end appliances. The plant features three 20-high mills and two skinpass mills, one of which operates inline. As they are subject to heavy wear in the production process, the rolls frequently have to be changed and ground. Even the slightest unevenness causes flaws in the strip surface.
“Roll management for the 20-high mills is particularly complex,” said Heinz Röther, Cold-Rolling Mill Team Leader at Dillenburg. The units operate with groups of 20 rolls of different thicknesses and in some cases different shapes. The rolls support each other so as to absorb the high forces produced in the stainless steel cold rolling process. Roll assembly components must be selected to maintain the roll gap of just a few millimeters required for the stainless steel strip. “Because the diameters of the individual rolls are constantly changing as a result of grinding, finding the right combination is an ongoing process,” said Röther.
“With RFID, roll management is largely automated,” said Herbert Schneider, Head of Information Management and Organization at Dillenburg. He explained that the new system not only knows each individual roll as if by name, it also knows where each one is, whether it is new, recently ground, polished, turned or worn, as well as details of its diameter and shape. The right roll diameters for the mills can now be assembled online, and the system also indicates the storage locations of the rolls and provides concrete suggestions for the optimum roll assembly.
Glass LF (low-frequency) transponders attached directly to the rolls in special recesses act as electronic labels. Information on the current dimensions, machining condition and period of use of each of the parts can be saved and organized in databases. UHF (ultra-high-frequency) transponders on cassettes, racks, tables and floor-level storage locations help to quickly locate the rolls, and RFID antennas on forklifts report cassette movements. Information on rolling, polishing and turning is entered via handheld computers, and a Java-based web application ensures that employees always have access to all information via handheld computers connected to a wireless network.
While this innovative solution can save time and money, RFID also has a positive effect on product quality. For example, employees in Dillenburg record details of when the rolls were installed in the mill stands and when they were removed, which helps reduce defects caused by rolls.
Because the stainless steel strip is covered in rolling oil during cold rolling, surface defects are only detected in the subsequent annealing process. Hours or even days can pass between these two production steps. Up to now it has been difficult to trace which roll was responsible for the defects because the strip can be up to nine kilometers long and wear out as many as five work rolls. Now the team in Dillenburg has much more accurate information about which roll was being used in the mill at a particular time and which section of the strip it was used for.
“We have succeeded in reducing the number of defects caused by rolls by up to 50 percent,” said Team Leader Röther.
In addition to ThyssenKrupp Nirosta’s Dillinger cold mill, the company is also planning to use an RFID based roll management system in the cold-rolling mill of the new stainless steel plant in Alabama.
