Pull Force of Permanent Magnet
The initial and general knowledge of the permanent magnet in most people includes the attractive or repulse force between the magnetic pole and the attractive force between the magnetic field and ferromagnetic objects. Pull force also can be utilized as a comparative measurement method in some specified circumstances besides conventional surface gauss, magnetic flux, and magnetic moment. Some formulas can roughly calculate the pull force of the permanent magnet. Then many magnet distributors have launched their online calculators based on relevant formulas. Our calculators are also available now. The complex case can be resolved by Finite Element Analysis (FEA).
The pull force of a permanent magnet is significantly dependent on the below factors:
Type and grade of the magnet.
Polar area of the magnet.
Operating Temperature.
The air gap between magnet and test plate. FEM simulation results showed that force decreased with an increasing air gap, and even a very small air gap has a huge impact on the force.
Test plate. The requirement with regard to the test plate can refer to the Test Method for Determining Breakaway Force of A Magnet developed by representative members of the Magnet Distributor and Fabricators Association (MDFA).
a. Material and composition of the test plate. Both 1018 cold rolled steel and other low carbon steel with high permeability can be adopted.
b. Thickness of the test plate. The test plate should be thick enough to carry all flux or result in a low pull force due to magnetic saturation. The surface gauss value on the opposite surface should be less than 5 Gauss.
