neodymium magnets grade
Help on constructing a dc electromagnet?
I wanted to do an experiment regarding the strength of repulsion between a large neodymium magnet and a dc electromagnet.
The following are the neodymium specs:
Type: Neodymium
Grade: N45
Dimensions (lwt): 2″ x 2″ x 1″ block
Gauss: ~13,300
Pull Force: ~230 lbs
Honestly, I get lost when I look at all other technical details regarding the magnets and electromagnets. All I wanted to do is to construct a dc electromagnet with similar “field strength” as that of the neodymium sample I have.
The materials I have access to are the following:
— electric copper wire – 10AWG
— 10-15amp battery charger
— 1″ diameter metal circular bar (for the core)
Issues I need to resolve:
1. Length of the core
2. Max number of windings / layers of windings
Thanks a million!
OK… you are going at this from the wrong perspective.
First of all, a measurement does not become better just because it becomes brute. If all you want is to measure the field of the magnet, a single piece of wire is what you want. No iron, no nothing, just one wire, a precision scale and a precision power supply.
If, however, you are aiming at replicating the strength of that permanent magnet, you are aiming way too high, yet again. That thing has a field of 1.3T. To make a 1.3T electromagnet is a hard piece of engineering work and I don’t think you will be able to get anywhere close. My best designs got something like 0.6T out of a fairly good size transformer core (10+lbs for one half) with a 100A power supply for about 15-30 seconds, after which the smell of burning insulation turned nasty.
Building magnets is not nearly as simple as mu_0 * current * number of turns * permeability of the core / length. Your coils will be burning long before you ever get close to 1T unless you optimize the hell out of this thing… which would require that you understand the theory. And then you would have to machine a core with special diameter/ length ration and the right amount of flux return path and god knows what… Not to mention high temperature wire and some way of cooling it… high pressure water cooling is the best, especially when run through hollow wires.
To give you an idea about industrial size lifting magnets:
http://www.rochestermagnet.com/store.asp?pid=8635
You can scale the lifting force by four for the smallest of these and then scale the size of the magnet by sqrt(4)=2. So that thing would have to be 3″ in diameter AND be designed as well as the professionals can do it. Yours will be quite a bit larger just to get there…
Good luck!
Railgun Animation – Version 2
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Set of 100 Grade N42 Super Strong Neodymium Disc Magnets 1/4 X 1/16 $6.65 100 Strong Neodymium Disc Magnets Each disc is 1/4″ diameter x 1/16″ thick These neat little magnets are great for the putting pictures and things on your refrigerator, arts and crafts, or just as toys themselves. This size makes them easy to handle. Just o… |
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216 Neodymium 5mm Sphere Magnets $44.99 216 round sphere magnets used around the house and for a variety of amusing puzzles…. |
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Industrial Grade 3DXY4 Magnetic Clip, Neodymium, 3 Lb, 1 In Dia $2.50 Magnetic Clip, Dia 1 In, Size 0.7 Oz, Magnetic Strength 3 Lb, Stability Temp 32 to 180 Deg F, Neodymium, Chrome Plated, Attached Clip… |
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Industrial Grade 3DYA5 Threaded Post Magnet, Neodymium, 90 Lb $25.60 Threaded Post Magnet, Thickness 0.315 In, Dia 2.035 In, Size 4.0 Oz, Max Pull 90 Lb, Magnetic Strength 90 Lb, Stability Temp 32 to 180 Deg F, Neodymium, Nickel Plated, Attached 10-24 Bolt, Includes Three Nuts… |
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Industrial Grade 3DXY3 Hook Magnet, Neodymium, 40 Lb $12.52 Hook Magnet, Dia 1.425 In, Size 1.4 Oz, Magnetic Strength 40 Lb, Stability Temp 32 to 180 Deg F, Neodymium, Chrome Plated, Attached Hook… |
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