# Alnico Magnets pole reversal

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?

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

 Here is a sheet of Alnico properties: