+strongest electromagnet for carrying the most possible weight?

[mike915]

I was searching the net and i found very interesting info of what stuff influence on the strength of the electromagnet:

- number of turns of the wire
- electrical current
- material of the core


I have to make it whit an specific wire: 20mts caliber 22

I was wondering if the shape of the electromagnet influence in the force because i found diferent types: shape 'I', shape 'C', shape 'E', shape 'U'
what would be the best for my particular purpose??

And the size of the core?? what should I use?? shorter and thicker, or longer and thinner.

well thanks for all your help.

 

[IRstuff]

"what would be the best for my particular purpose??"

Don't you think you should divulge what your purpose is?

TTFN
faq731-376

 

[EdStainless]

Surface of contact is critical.
There is no reason for the field to exceed the saturation level of what you are lifting.
As long as you generate enough field strength then you should opt for more contact.

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Plymouth Tube

 

[mike915]

Don't you think you should divulge what your purpose is?

PURPOSE: build a strong electromagnet for carrying the most possible weight.

Surface of contact is critical.
There is no reason for the field to exceed the saturation level of what you are lifting.
As long as you generate enough field strength then you should opt for more contact.

So.. I have 20mts of wire, if i want to increase the surface of contact I'll need to decrease the number of turns of wire but that would make the field weaker.. so I'll need to find a middle point between surface and turns where the force is maximum.
am I correct??

Do you know any formula for calculating the force in function of the surface of contact??

 

[IRstuff]

Is this for school?

TTFN
faq731-376

 

[dgallup]

What is an "mts"? If that is supposed to be meters you are sadly mistaken.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[EdStainless]

I hadn't even thought about the 20mts.

Let's see, what is max current for 22ga? Then figure saturation of steel in nA, then back out the cross section area.
It is going to be very small.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[MagBen]

there is a complicated formular to calculate the force between two magentized surface, the force is not linear with the distance. For a max force, i.e. no gap in-between. F is proportion to B^2 and A (B magnetic flux density, A the area of surfcae), so basically anything increase B and A will increase F. number of turns doensot matter much when the magnet is saturated (Max B). current follows the same fashion, if you have enough A.N, you get a max B ( there is additional B from the coil itself, but ot effective when the magnet is saturated). material of core with a higher B Sat has the potential to give a higher B.
C, U, E shapes are better than I, since the formers can form a close magnetic circuit, so a higher Bd, which is defined as the operating point. for a I shaped magnet, higher Bsat doesnot mean a higher Bd due self demagentization effect, in this ccase, the length the magnet, the higher the Bd.

 

[mike915]

there is a complicated formular to calculate the force between two magentized surface, the force is not linear with the distance. For a max force, i.e. no gap in-between. F is proportion to B^2 and A (B magnetic flux density, A the area of surfcae), so basically anything increase B and A will increase F. number of turns doensot matter much when the magnet is saturated (Max B). current follows the same fashion, if you have enough A.N, you get a max B ( there is additional B from the coil itself, but ot effective when the magnet is saturated). material of core with a higher B Sat has the potential to give a higher B.
C, U, E shapes are better than I, since the formers can form a close magnetic circuit, so a higher Bd, which is defined as the operating point. for a I shaped magnet, higher Bsat doesnot mean a higher Bd due self demagentization effect, in this ccase, the length the magnet, the higher the Bd.

Well thanks, so i will go for the c shape, and i will have to find a material with a high saturation limit, i think is iron with a high purity isnt it??, but do you know where can i find it??,do you know any device that needs it?
thanks for helping me

 

[IRstuff]

Is this for school? If not, then for what?

TTFN
faq731-376

 

[MagBen]

FeCo (commercially available) has the highest Bs, the second is pure Fe, in which the purity mainly affects permeability. FeSi is another choice if you cannot offer surficient Ampere Turns to saturate the magnet. Check with Carpenter (

http://www.cartech.com)

who supplies all of these soft magnets.

 

[teknasutra]

Beyond what has already been discussed above do not forget to pay attention to the capacitance of the coil circuit itself and the flux return path. Take a look at the Tesla bifilar pancake coil. [URL unfurl="true"]http://en.wikipedia.org/wiki/Bifilar_coil[/url] The resulting field pattern is such that there exists a constant field return from filar1 to filar2 along then entire circuit path. This results in a VERY small air gap and a + to - along the entire coil. Another rather pleasant by product is a decrease in the capacitance of the circuit even under load! Also take into consideration the magnetic moment of the materials you are going to be lifting. Depending upon the frequency and the required amperage you may develop an internal wave form that can result in very quick heating of the load.

Good rules of thumb. 1. Keep your coil close to the load. 2. Use a PWM to control your circuit as it will allow you to compensate for magnetic moment of load etc.

Have a great time!