Magnetisation

Which Material Can A Magnet Attract And Which Don't How Magnetism Works Understanding which materials respond and which don't is quite simple, but it depends on an understanding of how magnets work in general. The motion of electrons in an atom produces a small magnetic field, but ordinarily, this field is cancelled out by the motion of other electrons and their opposing magnetic fields. However, in some materials, when you apply a magnetic field, the spins of neighboring electrons align with one another, which produces a net field across the whole material. In short, instead of cancelling each other’s fields, the electrons in these materials join together and make a stronger field. In some materials, this alignment disappears when the field is removed, but in others, it remains even after the field has been removed. Metals That Attract Magnets Ferromagnetic Metals and AlloysFerromagnetic materials are attracted to magnets because their electrons spin and the resulting “magnetic moments” align easily, and retain that alignment even without an external magnetic field. Ferromagnetic materials such as iron, nickel and cobalt are therefore attracted to magnets, as well as rare-earth metals like gadolinium, neodymium and samarium.Alloys made from these materials are also attracted to magnets, Essentially, any alloy composed of ferromagnetic materials will also be magnetic. Metals That Don't Attract Magnets Paramagnetic Metals and MagnetismParamagnetic metals have a weaker attraction to magnets than ferromagnetic metals, and they don’t retain their magnetic properties in the absence of a magnetic field. Paramagnetic metals include platinum, aluminum, tungsten, molybdenum, tantalum, cesium, lithium, magnesium, sodium and uranium.Diamagnetic Metals and MagnetismDiamagnetic metals are actually repelled by magnets rather than to enhance it. These materials include silver, lead, mercury and copper.

1. Sufficient coercivity (and therefore enough electric current) must be supplied to completely magnetize the part. This condition places a lower limit on the value of current times turns. 2. Most of the energy stored in the capacitors is converted into heat within a few milliseconds in the coil. The time is too brief for significant amounts of heat to escape to the surroundings. The coil must have enough mass that the resulting temperature rise is kept low enough to avoid overheating which could destroy the insulation. In some cases, the coil (or part of it) could even be vaporized. 3. Rejection of heat from the fixture as a whole must be high enough to allow cycling at an economical rate (if the fixture is intended for production use). 4. Eddy currents in the fixture or magnet itself must not be high enough to prevent complete and even magnetization of the part, or overheat the fixture. 5. The fixture must be strong enough mechanically to take the high forces generated by the magnetic pulse without damage. It must be constructed with enough accuracy to locate the magnet poles to within the required tolerances. It must restrain the magnet and support it well enough that the part will not be broken by the magnetic forces, and yet must not fit so tightly that thermal expansion might jam or break the part. Fast and easy loading and unloading of the part must be provided for.

Most modern magnetmaterials have a "grain" in that they can be magnetized for maximumeffect only through one direction. This is the "orientationdirection", also known as the "easy axis", or "axis".Un-orientedmagnets (also known as "Isotropic magnets") are much weaker thanoriented magnets, and can be magnetized in any direction. Oriented magnets(also known as "Anisotropic magnets") are not the same in everydirection - they have a preferred direction in which they should be magnetized.

We use the description "Magnetized thruthickness" to identify the locations of the poles on our block magnets.  The thickness is always thelast dimension listed for block magnets. If you take one of our block magnets and place it on a flat surface with the thickness dimension as the vertical dimension, the poles will be on the top and bottom of the magnet as it sits.If you place one of the blocks so it is on a flat surface with 1/8" as the vertical dimension, the poles will be on the top and bottom as the magnetises. This means the poles are located in the middle of the 1" x 1/2" sides.