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Ordered in the morning, produced in the afternoon, loaded in the evening and shipped the next morning – deliveries of slit strip and material cut to order within 24 hours are just part of the normal daily routine for one of the largest European service centers for flat steel products. To achieve this, Becker Stahl-Service GmbH has invested in innovative production and storage equipment. The automated crane-served store for steel coils is a key element of the new production facility, where two Demag process cranes ensure that material is stored appropriately and staged in time for the production lines. The hardware and the warehouse management computer (WMC) is supplied by Demag Cranes & Components from a single source.
With more than 6,000 loading and unloading operations per month and shipping in four shifts, six days per week, Becker Stahl-Service in Bönen, Germany, provides just-in-time deliveries to satisfy its customers' wishes.
Established as a steel trader, the company, which is based in Unna-Bönen, has grown to become a steel service center that has more than 400 employees and which sells, stores, handles and processes steel.
The range of products includes wide band, slit strip, plates, blanks and trapezoid blanks in many finishes and coats. With more than 60 per cent of its products manufactured for customers in the automotive and automotive supply industry, the supplier has to meet the highly demanding quality and production standards of this sector.
An annual sales volume of some 1 million tonnes combined with stocks of approx. 200,000 tonnes and short production lead times has made the supplier a leader in the European steel trade sector. The company has been part of the Klöckner Group since 2010.
The cranes operating in the store at Becker Stahl-Service are a major component of the in-house logistics system, which link the production, storage and shipping operations with each other. They have a large impact on the efficiency and the flexibility of the entire processes. The maximum possible availability of the cranes has the highest priority. Two Demag Coilmaster process cranes are responsible for the semi- and fully automated handling of the steel coils at Becker. Reliable operation, is therefore, also ensured by the secondary crane system. Crane 1 serves the coil store in fully automated mode. Crane 2 operates under semi-automated control and is used for loading and unloading the incoming trucks as well as for serving the front zone of the store (quarantine zone). This crane can also operate in automatic mode.
The load handling attachment is innovative: Demag process cranes are being used with coil magnets for the first time in a coil store:
The material is delivered to and shipped by truck at the Becker Nord facility. The goods are lifted off the trucks and deposited in the quarantine zone by the Coilmaster crane under manual control. In this area, the goods are registered, i.e. labelled and issued with a coil record document . The coil data are transferred to the warehouse management system and the ERP system (Baan), where the data are compared with the specifications saved in the system.
A sample of every coil is cut for quality assurance. The data available at Becker goes all the way back to the steel supplier, which enables all physical and chemical coil data to be accessed.
After the quality assurance check has been completed, the coil is transported by crane under manual control to the transfer point for automatic handling. When the magnet engages the load, a laser beam checks to ensure that the coil is positioned in the center of the magnet. If necessary, a correction is made in the cross-travel direction. This ensures that the load is precisely picked up and positioned by the automatic crane in the store. The magnet operates with two levels of safety: in the first stage, the load is magnetized and raised at creep speed. When the magnet is safely engaged, the system automatically switches over to full load mode and the load is raised at maximum lifting speed.
At the transfer point, the operator switches the crane over to automatic mode. The warehouse management computer (WMC) assigns a location within the fenced-off storage area in front of the automatic zone. After the coil has been handed over, the crane returns to the quarantine zone, where it waits for the next unloading operation.
The WMS assigns a storage mission to Automatic crane 1 with details of the source and destination co-ordinates. Using laser sensors, the crane positions its hoist precisely above the coil and picks it up, while the crane weighing device measures the exact weight of the coil. The hoist unit raises the magnet and load to the highest hook position, where they engage a mechanical guide to prevent any load sway. The automatic crane then travels to the pre-defined storage position at maximum speed and transfers the coil to the store.
The store was designed according to geometric conditions. The widest coils are stored in the outer lines to utilize the crane approach dimension at the edge of the store. The warehouse management computer is aware of the dimensions, surface finish and grade of the materials. This enables the system to store the items appropriately.
The coils rest on so-called coil blocks, which reflect the different widths and diameters. Storage strategies that allow for the various types of material, including multi-stage restrictions for stacking items, for example, ensure maximum utilization of the available space as well as safe and reliable treatment of the material.
Items are retrieved as required in production or to customer order according to a coil staging list. Items are transferred to production via cross-shaped turntables, which represent the interface between the store and the machines. The process crane deposits the coils and reports completion of transfer to the machine tools via a "handshake" procedure. Partly used coils are also returned to the automated zone together with a data module via the turntable. To do this, the crane determines the current weight of the coil by means of an integrated weighing device.
Becker Stahl-Service has installed cut-to-length and slitting lines in bays 12 and 13, which are located immediately next to the store. Four manually operated Demag ZKKE double-girder overhead traveling cranes, which are equipped with radio controls, are used for handling the products in these production bays.
Bay 13 is equipped with a 35-tonne crane and a 28-tonne crane. Both of these cranes work with C-hooks for handling slit strip. Two 20-tonne cranes equipped with DR-Pro rope hoists and grabs for handling palletized goods operate in neighboring bay 12, where sheet metal measuring up to 4 millimeters thick is processed.
Cranes for coil storage and processing
Bay 12 (slitting lines)
*) ZKKW: Process crane with winch unit
ZKKE: Double-girder standard overhead traveling crane
Safe and gentle handling of steel coils with magnet lifting equipment.
Optimum space utilisation: the magnet system enables loads to be picked up from above – the steel coils can be stored with a gap of only 300 mm between them.
The space-saving arrangement of the steel coils enables the storage volume to be increased by 30 per cent.
Crane under manual control in the goods-in area; the coils are transferred to the automatic store after they have been registered.
The steel coils are precisely picked up and handled safely and gently in the automatic store
Trucks are unloaded in the delivery zone
Two automated cranes provide for fast handling rates in the coil store
Four double-girder overhead travelling cranes equipped with C-hooks in machining shops 12 and 13.
Coils being loaded after the machining operation.
Process cranes for precisely handling coils, sheet and plate metal and long material
Crane installations specially designed for mechanical engineering and automotive industry applications
Demag parts for unsurpassed reliability and long service life.