Core material question

[JerryRoy]

While researching electromagnet construction, I tried to find information about the feasibility of using laminated core (transformer core) as the core for a DC magnet.
The only thing I could find was an opinion that the laminations would not be as efficient as a solid core due to the air gaps between laminations, and the number stated was about 8%-10% less efficient for the laminated core.
If the coil is wound around the laminations, as they were in the transformer, would the flux strength coming out the ends of the laminated core be the same as a solid core if the cross sectional area of the laminations was 10% larger than the solid core?
Or stated another way, will the flux generated by the coil create flux across the lamination interfaces as well as through the end of the laminations.
Transformers all seem to have the edges of the laminations facing the center of the coil. If the faces of the laminations were facing the inside of the coil, would the permeability of the core be reduced?
Once again, your thought would be appreciated.

Jerry Roy

 

[EdStainless]

The only loss of efficiency is due to the air gas, it is like using a less dense material.
The flux density would need to be higher in the laminations, or you would need more gross cross section to make up for it.
Sometimes using lams can help since you can easily get high saturation material in that form.

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Plymouth Tube

 

[MagBen]

depending on the thicnkness of lams (stacking factor), the air gap will not only decrease permeability but the flux density. Increasing cross section area to compensate the loss of flux works in some degree.
the lam interfaces (air gap)still have flux flow from the coil, but the flux density or flux is much smaller than those within hte lams.

Do not understand this question: "Transformers all seem to have the edges of the laminations facing the center of the coil. If the faces of the laminations were facing the inside of the coil, would the permeability of the core be reduced?"

 

[JerryRoy]

Yes, after I posted that I realized that it didn't make a lot of sense.
What I was wondering was if the pole pieces that I made out of laminated iron would be more efficient with the laminations in the same plane as the core laminations, or would there be a reduction in flux transfer between the core and pole pieces if the pole piece laminations were perpendicular to the core laminations. (Flat face of the laminations laying on the ends of the pole laminations)
Edstainless leads me to believe that there would be a reduction if flux transfer (propagation) through the stack of laminations if the face of the laminations were placed on the end of the lamination pole piece, due to the air gaps between the laminations.
Without a Gauss meter, I don't know of a way to test the outcome of the two scenarios.
JR

 

[MagBen]

with the flux transferring the stack of lams?! that is like creating lots of air gaps down the flux road, and that would decrease permeability hundreds and thousands of times!

 

[JerryRoy]

Thanks, that is what I thought. I'll make sure that the flux path is applied to the sdges of the laminations.

JR

 

[Fabio88]

And what if the laminations are facing each other not parallel put at 90° each other? To understand what I mean: take a squared rod of laminated metal, cut it into two part and then rotate one of the two part of 90° along the axis of the rod..