Design and analysis of a thin sleeve for high-speed magnet drums in eddy current separation systems

Abstract

Eddy current separators, which are widely used in the recycling industry for the separation of non-ferrous metals, rely on the electromagnetic repulsion generated by eddy currents induced by a rotating magnet drum. As such, enhancing the separation rate of the magnet drum is vital for the recycling industry. Despite the existence of various studies aimed at improving the separation rate, the issues associated with the magnet drum’s sleeve remain unaddressed. This study introduces a comprehensive methodology for designing magnet drum sleeves for use in eddy current separation systems. A stress model was developed to analyze the relationships between the sleeve’s primary design parameters, such as interference fit and thickness, and various secondary parameters, such as rotation speed, size, material properties, and manufacturing processes. This study proposes optimal design points to minimize sleeve thickness, potentially enhancing both separation efficiency and design flexibility. The study’s findings emphasize the importance of maximizing the interference fit to maintain compressive stress between the magnet and core, preventing magnet scattering. However, there is a limit to increasing the interference fit due to sleeve breakage, and there are also certain constraints, such as the fact that material properties and manufacturing tolerances often require increased sleeve thickness. The analysis used in this study integrates these factors, emphasizing the sleeve’s critical role in eddy current separation systems. The results demonstrate the potential for more precise and improved designs that will enable higher rotation speeds, stronger magnetic fields and induced force, and narrower gaps between the magnet drum and the target objects, thereby enhancing the separation performance to a significant degree.