DC induction heating of aluminum billets by means of superconducting magnets

The heating process of an aluminum billet rotating in a static magnetic field produced by superconducting coils is analysed. The case of a billet with standard dimension rotating in a uniform DC magnetic field is examined and the main heating parameters, i.e. heating time, total power injected and temperature difference, are evaluated for different values of angular velocity and magnetic field. The field profile suitable to meet the specifics of and industrial heating process in terms of temperature homogeneity and heating time is determined. Starting form this profile the layout of the magnet is arrived at and some considerations on the operating condition of the superconducting windings are reported. Finally the mechanical stress in the billet due to weight, centrifugal effects, applied torque and resonance is examined by taking into account the weakening of the material properties with the increase of temperature and the practical limits of the heating process are evaluated.