When a person things of a magnet, generally the first thing that comes to mind is the red horseshoe with the silver tips. Odds are, your first exposure to a magnet was one just like the ones HSMAG Magnets sells for the science classroom: a horseshoe shaped magnet.
Why a horseshoe? What is the advantage to shaping a magnet like this? Are stronger magnets more effective in this shape? Here are some answers!
The Pulling Force is Stronger
While that might seem like the most uncomplicated answer, it really is true. When you make a magnet with both poles right next to each other, the pulling force of the magnet is increased. When you have both poles side by side, the magnetic field of the magnet is concentrated into the steel that it is being attached to.
With a bar or cylinder magnet, the other pole is hanging out in free space at the opposite end. This means a whole half of the force is wasted.
Coercivity is the measure of just how much strength it takes to demagnetize a magnet. The stronger the magnet, generally the stronger the opposite field needed to make it lose its magnetic pull. Modern magnets are designed not only to have a lot of pull force, but also to have very high coercivity.
This was not always the case. When magnets were first manufactured, they were made of iron. While iron is a very good metal to make a magnets with, it does not hold that magnetic charge very long. As a matter of fact, iron is so bad at holding magnetic charge, quite often the charge can be removed by the magnet’s own field.
Shape Affects Coercivity
Shape has a huge effect on the amount of coercivity that a magnet has. For example, a long cylinder magnet has a much higher coercivity than a very thin disk. A horseshoe shape is one of these types.
A horseshoe acts like a long cylinder. This means that the shape increases the amount of magnetic power needed to demagnetize it, just by the way that its shape generates the magnetic field.
Historically this was the only way that iron workers could get magnets to hold their magnetism. If they tried to shape a magnet as a thin disk, or a bar, the magnets would quickly demagnetize themselves.
What about Neodymium?
The thing about rare earth magnets, like neodymium, is that they already have very high coercivity. Because of this strength, it is not necessary to shape them as a horseshoe. As a matter of fact, shaping a neo magnet like a horseshoe has little effect at all on the strength or on the coercivity.
If you have any questions about types of magnets and how they might work for your purposes, please contact us for more information.