Determination of load capacity for magnetic leadscrew drives

Magnetically coupled leadscrews can have finer pitch than can other types of leadscrews, because the threads of the nut and the shaft are not meshed into each other This feature can lead to better precision for motion control. To achieve contactless coupling, this type of drive uses aerostatic suspension between the nut and the shaft of the magnetically coupled leadscrew. Determination of load capacity for such drives is discussed in this study. Boundary conditions for the air gap are derived and used to solve the corresponding Laplace equation. The result is then used to calculate air gap permeance and obtain the operating point of the magnet. Finally, relationships between load and design parameters are established for preliminary selection of component dimensions and material properties.