Can Alnico Magnets Undergo Pole Reversal with a Magnetizer?

[zydubion1]

An cylindrical alnico magnet is 1/2 inch diameter and 1 inch long. It is magnetized through its length. I realize that this magnet can be magnitized over and over again. But can the poles be reversed if subjected to a machine that magnetizes and de-magnitezes magnets? Also, where can one purchase such a machine? What are they called? Are there small table-top units availabe for home experiments?

 

[Bob S]

Suppose you wanted to build a dc magnet that could go to 1.6 Tesla, and re-magnetize your Alnico magnet. Suppose the gap was 0.025 meters, and the remainder of the path was 1 meter in iron ( "C" magnet) with a permeability u of 5000. The total amp turns you will need is

NI = 1.6 x 0.025/u₀ + 1.6 x 1.0/u u₀ = 32,000 + 260 = 32,260 amp turns, where u₀ = permeability of free space ( 4 pi x 10^-7 Henrys per meter).
So you will need say 460 turns at 70 amps (peak).

See http://www.gmw.com/electromagnets/dipole/5403/5403_Specs.html

[Edit] Here is a sheet of Alnico properties:
http://www.dextermag.com/uploadedFiles/Alnico_Data_Sheet.pdf
Some Alnico's have a residual magnetization of 1.35 Tesla, so you probably want to push Bmax up to 1.6 Tesla. You can do it with a pulse several seconds long, so you can use an air-cooled magnet much smaller than the one shown in the GMW web page. You can use a capacitor bank to provide the pulse. The voltage required depends on the resistance of the wire coils (e.g., 10 Ga formvar wire), and the pulse length on the RC time constant. If your iron is solid, the pulse length must be long enough for the eddy currents to die out.

 

[astrokreng]

I can confirm that alnico magnets can undergo pole reversal through a process called magnetization. This involves exposing the magnet to a strong magnetic field in a specific direction, causing the atoms within the magnet to align and create a magnetic field. This process can be repeated multiple times, allowing for the poles to be reversed.

There are machines available for magnetization and demagnetization of magnets, commonly known as magnetizers or demagnetizers. These machines can be found at industrial supply stores or online. Depending on the size and strength of the magnet, different types of machines may be needed.

For a small cylindrical alnico magnet, a table-top magnetizer or demagnetizer may be suitable for home experiments. These can also be found online or at hobby stores. However, it is important to follow safety precautions when working with magnets and strong magnetic fields.

It is also worth noting that the strength and effectiveness of a magnet may decrease with each magnetization and demagnetization cycle. Therefore, it is important to carefully consider the purpose and frequency of pole reversal before subjecting a magnet to this process.