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I am indebted to my colleague, Mr Tony Grainger, for the JavaScript program which performs the calculations for this page.

Electromagnet Design Tool

The program on this page is a powerful aid for designing magnets for the "Magnabend" electromagnetic sheet metal bending machine.

The program produces detailed Calculated Results, and also draws, in real time, the magnet cross section that corresponds with your typed-in 
Magnet Input Data.

calculator goes here
cross section goes here

How to use this page:

An electromagnet consists of 2 basic parts;  an electric circuit (or coil)  and a magnetic circuit (or flux path).
An electric current in the coil induces a magnetic current (flux) in the magnetic circuit  (Magnetic potential =  N x I ampere turns).

The program on this page brings together all the salient features of both these basic parts and makes detailed calculations to inform your electromagnet design.

Feel free to experiment.

 You can type any numbers you like into the input fields. The program will immediately make all the relevant calculations and present them in the "Calculated Results"section.
 At the same time both the geometry and the dimensions for electromagnet cross section drawing will be automatically updated
Additional Calculated Results can be displayed if desired by clicking on the "Details +/-" button.  These additional results will not usually be needed but may be useful for advanced designers.

To reset the program to the default numbers just refresh (or reload) this web page.

The calculations assume that the coil is made from copper wire (resistivity = 0.0171 Ωm at 20ºC) and that the magnet body is made from mild steel SAE 1020.
The relationship between the magnetisation in the steel and the field strength is non linear and cannot be represented by an equation. The curve is usually referred to as a B-H curve.

The calculations on this page use a table lookup for the B-H curve followed by an iterative method to obtain accurate results for the flux density pertaining to the particular magnet configuration.

See also the Coil Calculator.

Magnetisation Curve