Christina H Chen, Hui Meng, and Min Fan

Presented on 2018 IEEE International Magnetics Conference, at Singapore

The Maxwell magnetic force equation F = B^2*A/(2μ0) [1-6] can be used for determining the magnetic force of magnetic components, where F is the force in newton (N), B is the flux density in tesla (T), A is the area of cross-section in square meter (m^2), and μ0 is the permeability of the vacuum (4π×10−7 H/m). The formula can be converted to an easy to remember expression of F = 40B^2*A, in which the unit of A is cm^2. This equation says that if the field is 1T, and the area is 1cm^2, then the magnetic force is 40N or 4kgf. However, it is somehow difficult to determine the B value in many practical cases, and the accuracy is usually not satisfactory. Computer simulation using finite element method can determine the magnetic forces with various boundary conditions, but usually it is not convenient for industrial users. In this paper, we report several simple equations, which are established based on the large database generated by using 3D computer simulation. The users can use the equations to obtain the force by simply inputting the magnet’s Br, area and thickness. The effect of load line is also analyzed in this paper.