Alnico Magnets (Al-Ni-Co)

alnicomagnets
alnicomagnet

Alnico magnets are made primarily from aluminium, nickel, cobalt, copper,
iron and sometimes titanium. They can be either cast or sintered.

Sintered Alnico

Sintered alnico is made from a powdered mixture of ingredients that are
pressed into a die under tons of pressure, sintered in a hydrogen atmosphere
and then cooled either within a magnetic field or without (anisotropic
Vs Isotropic).

Cast Alnico

Cast Alnico melted and poured into a mold. Once solidified, the material
is rough ground and then heat-treated and cooled, sometimes in a magnetic
field. When treated in the presence of a magnetic field, the magnet is
called anisotropic. This orients the material to take on maximum magnetization
and allows a higher gauss level. A cast magnet that is not heat-treated
in a magnetic field is called Isotropic. After heat treatment and cooling,
the material can be ground to specific tolerances and then magnetized.

Attributes of both Cast and Sintered Alnico

  • Very temperature stable great for high heat applications
  • Maximum working temperature 525ºC – 550ºC
  • May be ground to size
  • Does not lend itself to conventional machining (Hard and Brittle)
  • High residual induction and energy product compared to Ferrite material
  • Low coercive force compared to Ferrite and rare earth materials (more
    subject to demagnetization)
  • Most common grades of Alnico are 5 and 8

Applications of Alnico Magnets

Magnetizing and Handling

Magnetizing is done after the magnet has been machined to the correct
tolerances. Care should be taken when handling alnico material since it
is brittle and chip or break if dropped on a hard surface. Also, because
it has a low resistance to demagnetization, it will lose power if it is
stored improperly (poles repelling each other). For best results, store
magnetized alnico so that pieces are attracting each other, or with a
steel keeper.

Magnetos, Separators, sensors, electron tubes, traveling wave tubes,
radar, holding magnets, coin acceptors, clutches and bearings, motors,
distributors, relays, controls, generators, receivers, telephones, microphones,
bell ringers, guitar pickups, loudspeakers, security systems, cow magnets.

Machining

Alnico is a very hard and brittle material and does not lend itself to
conventional machining. The STAR TRACE Employs Experienced Machinists
and the proper equipment to grind alnico to its require Ship.

Typical magnetic and Physical Properties of Alnico Magnet
Material

alnico_specification