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Posts: 6

# Magnetic Field Repulsion

09/14/2011 1:44 AM

what is the best formula to measure feild repulsion in a static and charged state. where an electro magnet is the base and a neo is static. weight is an issue and there must always be enough lift to maintain a constant of 3800 lbs with a max load of 5400 lbs while the electro magnet is used to move the load ?

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Richard Sleeth
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#1

### Re: Magnetic Field Repulsion

09/14/2011 2:17 AM

Formulation not very clear. try to make it better.

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Join Date: Apr 2009
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#2

### Re: Magnetic Field Repulsion

09/14/2011 5:13 AM

I need to know the formula so that I am able to determine the amount of lift I can achive by placing a pair of neo magnets opposite of one another . I also need to be able to find the ammount of lift within the feild of a neo magnet opposite an electromagnet

All the formulas I have found only show lift and depth of feild based on teslas law on magnetic feild strength allowing for transmission through nonferrous material for lifting ability, or based on the thickness of the ferrous material

I hope this clears things up enough to allow me to get somewhere.

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Richard Sleeth
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#3

### Re: Magnetic Field Repulsion

09/14/2011 6:36 AM
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#4

### Re: Magnetic Field Repulsion

09/14/2011 9:44 AM

Magnetic fields (not feilds) have to be COMPUTED but there is no valid formula for all geometries since there different factors to consider as for instance the field which is not used via the environmental air. The force between two PM depends on their geometry and the ratio between gap and transversal dimensions. It also depends on the properties of the other materials near to the magnets, if steel it will be different from copper or aluminum. It is not so easy as it is expected. Such a problem as yours should be treated by a Finite Element Analysis. Depending on the geometry of the parts it can be solved with a 2D soft or it could be compulsory to use 3D programs much more complex and not available without a lot of money payed for. 2D are even available for free and are -some of them - of very high quality. From an other point of view the Neo PM are of different strength and for a load as yours the prices can be an important criterium for the choice. If it is a student project better try to get a help from a department dealing with magnetics. If it is not try to find a professional in this field.