I suppose I should give a motor 101, on whats going on here, for those who aren't sure yet how this works.
Otherwise,.. if this is old hat for you, or to boring, then page down.
This is just my view, or interpretation,.. so far, and trying not to get to technical.
When you wrap a coil of wire around an air core, and put some power to it, you get a magnet. We all know that.
It creates a field,..but the field isn't concentrated yet, it's wide.
When you place a piece of steel into it, it concentrates the filed. Hundreds, even thousands of times, towards each end.
Each face of the core now has the strongest magnetic flux point, and that gives the motor a solid place to grab and push from.
Thats why virtually every motor uses steel cores. Real power is made from using strong, concentrated flux points.
Steel is magnetic. That is one thing,.. but it's also a conductor, and thats is another.
All 'metals' are conductors because they contain within their structure, billions of 'free electrons'. Free electrons are extra
electrons that don't belong any place in particular. They just hang out.
Electricity uses them to 'move' with, a lot like water in a hose.
But 'magnets', can also move electrons in metals,.. if you get them close enough.
'Induction' is the act of the magnet moving the free electrons around in the metal.
'Induction heat', is the result of moving them super fast.
Moving a magnet across any metal, is like moving your finger through water. Theres a slight pressure on the front of your finger,
and a swirl on the back side. If you move it fast enough through the water, as if you were water skiing, then there would be a lot
of pressure, and a lot of heat.
This pressure and swirling of fields, and electrons, is what we call 'eddy current', It's not so bad at low levels, but at motor
speeds it will become a problem. It creates a drag, and ultimately, .. heat.
Big motors,.. big heat problem.
A great deal of thought over the ages has gone into trying to figure out how to keep this from happening.
The most common technique is to use thin laminations of steel bundled together. The thinner, the better. The long thin shape of
the steel, when placed in the right direction, prevents, or reduces the swirling eddy effect.
The steel also has silicone in it, which helps reduce the affect even further.
Another way to do it, is to use a 'ferrite core'. Ferrite is a form of powdered iron that is glued, or bonded together. The idea is
that all the millions of individual little pieces of steel each contain and reduce the eddy currents within itself. It works quite well,
except that there is a reduction in the magnetic flux power, because there is a reduction in the amount of steel, taken up by the
glue,.. and, a loss because of the space in between the particles.
There are many kinds of ferrite core materials. Some are very Hi Tech, and contain metal spheres that have layers inside, in specific ways to reduce eddy currents.
There are many different types of ferrite 'metal mixes', each designed for a specific electronic purpose.
The drawback to ferrite cores for motors, is the magnetic reduction, and the strength of the material. Ferrite is brittle, and cracks, whereas laminations are very strong.
Motors and big power transformers use laminations, and small transformers and high frequency electronics use ferrite.
Making a core from laminations is hard. You have to make many, many pieces and each one has to be exactly like the next,
usually requiring laser cutting, or a punch press.
Ferrite cores are easier to manufacture, precisley bonded and heated under pressure, the cores can be cast, in large numbers,
for most applications.
But it can also be made at home, in a little cruder form.
Thats what I'm hopping to do here, (famous last words), ..make the cores, (which could turn out to be a complete failure).
I need to devise a way to measure the difference in magnetic strength between the two types of cores. To see how much I've lost.
A Gauss meter, which measures magnetic fields, would make that easy, but are typically to pricy, for just one motor.
OK, hope that wasn't to painful,.. enough of this talk!
Time to make something!