Attraction of the cylindrical magnet to the steel plate

QuickField simulation example

Cylindrical permanent magnet is pulled toward the ferromagnetic plate.

Problem Type
Axisymmetric problem of DC magnetics

Geometry

D = 2" (50.8 mm) - magnet diameter;
L = 0.65" (16.51 mm) - magnet thickness;
t = 2" (50.8 mm) - plate thickness;

Given
magnet grade N35, H_c = 954930 A/m, B_r = 1.26 T;
relative magnetic permeability of plate μ_steel = 1000.

Task
Calculate the pulling force of the magnet toward the steel plate.

Solution
To calculate the pulling force accurately, and avoid integration along the edge dividing media with large difference in magnetic permeabilities, we place the magnet at a small distance δ = 0.005" (0.127 mm) from the steel plate. Integration contour is drawn in the air around the magnet.

Result

* Reference: www.kjmagnetics.com.

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