Winding a strong electromagnet

[capthook]

Any recommendations on coil/core geometry/dimensions?  Something like how a Brooks coil dimensions is proposed for an air core design?
Maximum width/depth of windings/ distance from core?
Core width/length? etc...

- - -

Kator - I've tried to upload the Ebook to the uploads section of this site - but stated file size limit is 5meg and the Ebook is 12meg.  However - the link given before IS active and links to the .pdf download of the Ebook....

- - -

Silicon Steel  (Electrical Steel)

"When low carbon steel is alloyed with small quantities of silicon, the added  volume resistivity helps to reduce eddy current losses in the core.  Silicon
steels are probably of the most use to designers of motion control products
where the additional cost is justified by the increased performance.  These
steels are available in an array of grades and thicknesses so that the material may be tailored for various applications.  The added silicon has a marked impact on the life of stamping tooling, and the surface insulation selected also affects die life.  Silicon steels are generally specified and selected on the basis of allowable core loss in watts/lb.

The grades are called out, in increasing order of core loss by M numbers,
such as M19, M27, M36 or M43, with each grade specifying a maximum  core loss.  (Note that this means that material can be substituted up , as M19 for M36, but not vice versa.) The higher M numbers (and thus higher core losses) are progressively lower cost, although only a few percent is saved with each step down in performance.  M19 is probably the most common grade for motion control products, as it offers nearly the lowest core loss in this class of material, with only a small cost impact, particularly in low to medium production quantities.
In addition to grade, there are a number of other decisions to make regarding silicon steels.  These are:

1. Semi vs. Fully processed material,
2. Annealing after stamping,
3. Material Thickness,
4. Surface insulation. 

  Fully processed material is simply material which has been annealed
to optimum properties at the steel mill.  Semi processed material always
requires annealing after stamping in order to remove excess carbon as well as to stress relieve.  The better grades of silicon steel are always supplied fully processed while semi processed is available only in grades M43 and worse.  The designer considering semi processed M43 should evaluate Low Carbon Steel which may provide equivalent performance at lower cost.

Even though annealed at the mill, fully processed material may require further stress relief anneal after stamping.  The stresses introduced during punching degrade the material properties around the edges of the lamination, and must be removed to obtain maximum performance.  This is
particularly true for parts with narrow sections, or where very high flux
density is required.  In one instance, a tachometer manufacturer was able to
reduce the stack height in his product by 10% by annealing after stamping.  The annealing cycle requires a temperature of 1350-1450 F in a non oxidizing, non carburizing atmosphere. Endothermic, nitrogen, and vacuum atmospheres all work well. The selection of lamination thickness is a fairly
straightforward trade off of core loss versus cost.  Thinner laminations exhibit lower losses (particularly as frequency increases), but thinner material is more expensive initially, and more laminations are required for a given stack height.  The most common thicknesses are .014 in., .0185 in., and .025 in. (29 Gauge, 26 Gauge, and 24 Gauge, respectively.)  These thicknesses are supplemented by thin electrical steels, available in .002, .004, and .007 in. thick.  Thin electrical steels are available in one grade (Equivalent to M19) and are made by re-rolling standard silicon steel.  Due to substantially higher material cost, thin electrical steel is used primarily for high performance and high frequency applications.  In order to gain full advantage from a laminated core, the laminations must be insulated from one another.  The simplest way to do this is to specify a surface insulation on the raw material.  Silicon steels are available with several types of insulation: 
--C-0:
Also called bare, or oxide coated.  This is a thin, tightly adherent oxide
coating put on the material at the steel mill, or during the annealing process
after stamping. This is the lowest cost insulation, but offers little
resistance.
--C-3:
Enamel or varnish coating which offers excellent insulation, but parts so
coated cannot be annealed after stamping.
--C-4:An inorganic coating providing higher resistance than C-0, but which will withstand annealing temperatures.
--C-5:
An improved inorganic coating similar to  C-4 but with significantly higher
resistance. It withstands annealing well in most cases.  This is probably the
best choice for most performance sensitive applications.  The main drawback to C-5 is  an increase in tool wear due to abrasiveness."
- - -

Anyone have a source for ordering small quantities of electrical steel?

[scotty1]

Hi all, I have loads of thin iron. 
I have to keep it on my trolley jack it is so heavy..maybe 400lbs or more 
I took it from an old electric induction furnace...the strips are about 3 feet long x 3 inches wide, very thin.
BTW, if you want to make a strong EM for lifting, then you need to put an iron tube around the coil and core....You can do better still...connect one end of the iron core to one end of the iron or steel tube with a plate of iron or steel....then at the same end of the coil,  if the core was a N pole, the tube will be a S pole.
http://outdoors.webshots.com/photo/1309921210053353196vJTSMY
My wife gives me "THE LOOK" when i bring things like 400lbs of iron strips home 
"BUT I MIGHT BE ABLE TO USE IT ONE DAY"   I say 
Everybody here surley understands that.
Scotty.

[Kator01]

 Hi capthook,

thank you. I simply can not believe it how scattered information in the web is. But anyway look here,  even searched with google´s book-search-engine and could not find it.

Regards

Kator01

[gyulasun]

Hi Kator01,

I receive the same page you show above, I think it is country-specific what we can download...  Probably it is ok for download in the USA but not allowed in Europe...

Maybe it could be uploaded to a free file sharing site?

rgds, Gyula

[capthook]

Huh - must be a US thing.
Google caused a bit of an uproar when they started the book scan project.  Royalties issues etc.
Just a week ago or so they settled a law suit for over $20 million relating to it.
Maybe it will clear some of the hurtles in the near future.

I upload the file to a free file service:

http://www.filepanda.com/file/vjdxk5ztmx4m/

It will take a min. or two (or more on dial-up - 12 MB) to download and then opens a .pdf window.
You can then click on "save a copy" in the top-left menu to save to your hard drive.