A Boost for Electrical Steel Sheet

SMS group strip processing line supports thyssenkrupp Steel Europe

The commissioning of the new annealing and insulating line in Bochum is an important milestone for thyssenkrupp Steel Europe (tkSE). The electrical steel strip processing line, supplied by SMS group, enables tkSE to produce high-grade NGO steel (non-grain-oriented electrical steel strip). This product is characterized by its special magnetic properties and low core losses, which are crucial for energy-efficient motors, generators and applications in the electromobility sector.

The annealing and insulating line is designed for an annual capacity of 200,000 t and processes electrical steel strip in widths of up to 1,350 mm and thicknesses of between 0.20 and 1.00 mm at a process speed of up to 150 m per minute. The strip treatment process comprises a precise heat treatment in which the cold-rolled strip is first cleaned and subsequently recrystallized. After that, a layer of insulating varnish is applied to ensure optimal electrical properties. As a result, tkSE will be able to meet the growing demand for high-performance electrical steel strip and strengthen its role as a pioneer in sustainable and energy-efficient processes and products for the future.

Technological highlights and production process

SMS group supplied the complete strip processing line from a single source: In addition to the mechanical equipment, process engineering, as well as electrical and automation systems, subsidiaries provided the Drever furnace technology, Elotherm induction heating within the furnace and the automated Amova coil transport system. The technological core of the line is the combined heat treatment and coating process. The Drever furnace features a patented rapid heating system that attains temperatures of up to 1,100 °C. A combination of natural gas-fired radiant tube zones, Elotherm inductors and electrically heated zones is used to control the annealing process and optimize the microstructure of the electrical steel strip. For example, materials with special magnetic properties and low core losses are produced in this way. The intelligent furnace control system I-Furnace optimizes the production process using data-driven models that predict the material properties and allow specific adjustments to be made during production. This results in high material quality, an improved CO₂ balance, and lower production costs.

An essential element of electrical steel strip production is the coating technology that is integrated in the line and used to apply a layer of insulating varnish. The technology comprises two horizontal coating systems (roll coaters), which were developed especially for electrically insulating coatings and a flotation furnace for drying purposes. This setup ensures that the insulating varnish is applied to the strip surface in very thin, uniform layers of up to 0.5 µm without any flaws, and is dried in a contactless manner.

Technological innovations for efficient production and digital integration

The furnace rolls as well as the pay-off and tension reels in the new line are equipped with X-Pact Torque Drives, which transmit high torques directly and without having to use additional gear units. These compact and efficient direct drives minimize energy losses, reduce noise levels and require minimal maintenance. The entire plant was engineered using 3D-modeling. In this way, potential risks were minimized at an early stage and a seamless integration of the new plant into the existing infrastructure was ensured. SMS's X-Pact Plug and Work concept for conducting automation integration tests using the plant's digital twin enabled final optimizations to be made before the equipment was installed. This approach allowed the facility to be put into operation within a shorter time.

The project was successfully implemented in an existing industrial environment at the tkSE site in Bochum. With its lifecycle partnership approach, SMS offers continuous support with digital services and technical assistance to ensure maximum efficiency and availability of the plant throughout its entire lifecycle. To increase operational efficiency, the line is equipped with an automatic Amova coil transport system (A.C.T.). This system uses driverless transport technology to optimize coil handling and help make the production process more efficient.

(Source: SMS Group)