Building a more powerful electromagnet

[Rozy94]

Hey so I'm trying to build a few poweful electromagnets and I need some help because i don't really know much about the topic. What gives an electromagnet more power? Number of wire turns? Multiple layers of wire turns? Is it amps or volts that gives them their drive? Also what's the best gauge of wire? I'm using 22 AWG enameled magnet wire right now on a two inch diameter iron rod. I'm thinking of moving up to 20 or 18 gauge wire but I'm not sure if that would be better. Any help you can give me would be great! Thanks!

 

[OldEngr63]

The key factor is ampere-turns, so if you increase either current, turns, or both you will increase the strength of your magnet.

 

[cragar]

And you might need to cool the wire, if it gets hot you will have a drop in current.

 

[sophiecentaur]

I have to ask you how 'powerful' do you want your magnet to be? The answer to this question will affect your design from the very start.

 

[Rozy94]

Um honestly as strong as I can get it, what kind of design changes are you talking about?

 

[sophiecentaur]

That answer isn't any use, I'm afraid. Would you be prepared for your magnet to weigh two tons and take a thousand Amps? We have to start with some definite parameters.

 

[OldEngr63]

Is Your magnet going to operate steady state, or will it be a surge operation -- extreme current for a very brief time?

This will affect how much inductance you can afford to have in the winding.

 

[Rozy94]

Ahh ok, so it's needs to be fairly small buty as long as it's not ridiculously heavy the weight doesn't really matter, under 100 pounds would be good. I'm useing a car battery to run it right now, but i can change that out for something else, but the power source needs to be portable and rechargeable so a car battery seemed like it would serve this purpose pretty well.

 

[Rozy94]

Is Your magnet going to operate steady state, or will it be a surge operation -- extreme current for a very brief time?

This will affect how much inductance you can afford to have in the winding.

It's going to operate at a steady state, it's going to be constantly on for long periods of time.

 

[Bob S]

Review the drawings and equations in the attachment, especially Eq (6). The magnetic field B in the gap is proportional to the amp turns NI, and inversely to the gap height G. Based on this, what magnet design do you want (need)?
Are you more interested in 10 amps for several hours, or 100 amps for a few minutes? The resistance of the coil has to be designed specifically for the current required. Calculate the number of turns you want, then look up copper wire resistance in http://www.powerstream.com/Wire_Size.htm.