2 min reading time
Story 036 – 2014 – Sustainability Processes

Globally leading example of sustainability

High-temperature superconductor technology for billet heating

Wieland uses a completely new, particularly energy-efficient process to heat cast billets for extrusion: high-temperature superconductor technology uses extremely strong magnetic fields that penetrate the billet and thus provide homogeneous heating.

Semi-finished products require heating to comparatively high temperatures several times during their production - not only during melting and casting, but also during hot forming, pressing or rolling, and during the heat treatment process. Here, the material is heated to up to 80 percent of its homologous melting temperature. All annealing processes must be carried out one after the other, and the material must be reheated each time – starting from room temperature. This is a very energy-intensive procedure and reason enough for Wieland to optimize its processes in terms of energy consumption with innovative solutions and to use processes that are as energy-efficient as possible.

An impressive example of this is the introduction of high-temperature superconductor technology (HTS) for induction heating of extrusion billets. In this process, the billet to be heated is positioned within an enormously strong magnetic field and rotated by strong electric motors. The highlight here is that the superconducting property of the magnetic coil means that it operates largely loss-free with degrees of efficiency of 60–80 percent, and massive cooling systems are not required.

On the one hand, this means significantly improved energy efficiency compared to other processes and thus an important contribution to the sustainable use of resources. A further advantage is the optimum temperature homogeneity: The currents induced in the workpiece itself have a great depth penetration, heating the bolt very evenly, quasi "from the inside out". An effect that creates exemplary quality conditions in the further hot forming process.

Already in 2007 Wieland carried out a preliminary study in close cooperation with its supplier of these plants. Numerous adjustments and modifications were necessary before the first system to heat cast billets for extrusion could go into operation in 2010. The first HTS billet heater went into series operation in Vöhringen in 2014. Just how innovative and sophisticated the HTS technology is in terms of process engineering can be seen from the fact that not even a handful of such plants exist worldwide to date.

Bolt during loading

Billets being loaded into the HST system. Clearly visible are the two "plates" between which the workpiece is clamped.

Electric motors

In order to rotate the billet in the magnetic field, strong electric motors are required - well visible here. A driving force of 800 kilowatts acts on each workpiece.