Go to Navigation Go to Content

What is an Alnico Magnet?

custom alnico magnets

Alnico magnets, composed of primarily aluminum (Al), nickel (Ni), and cobalt (Co), were developed in the 1940's. This class of magnet remains a preferred material because of its excellent temperature stability, high magnetic flux density, and resistance to corrosion.

Alnico magnets are manufactured through a casting or sintering process. The casting process allows for the magnet to be manufactured into intricate and complex shapes. Sintered Alnico is made from a powdered mixture of ingredients that are pressed into a die under tons of pressure. The Sintering process allows for the magnets to be manufactured to tighter tolerances and higher mechanical strength.

Alnico Magnet Applications

  • Guitar pickups
  • Separators
  • Sensors
  • Radar
  • Holding magnets
  • Coin acceptors
  • Motors
  • Relays
  • Controls
  • Generators
  • Receivers
  • Telephones
  • Microphones
  • Bell ringers
  • Loudspeakers
  • Security systems
  • And much more

Custom Alnico Magnet Shapes

Magnetic Hold can customize any magnet shape. We work with you to personalize your magnets for your application. Common magnet shapes include:

  • Rods
  • Bars
  • Assemblies
  • Horseshoe
  • C-shaped
  • Cylinders
  • Rings
  • Channels
  • Arc
  • Disc
  • Block
  • Sphere
  • Plugs

Cast Alnico Magnets

The most common Alnico cast magnets are in grades 1, 2, 3, 5, 6, 8, and 9. They are best suited for applications exposed to operating temperatures above 400 ° Fahrenheit. They maintain approximately 85% of their room-temperature strength up to 1000 ° F. They become completely demagnetized at approximately 1600 °F. For best results with Alnico 5 magnets, the length should be no less than 5 times the cross section diameter or the diameter of a circle equal in area to the cross section.

alnico multipole magnet

Horseshoe cast alnico magnet

 

circle alnico magnet

rare earth metals

See table below for cast Alnico magnet properties.

Build Your Custom Magnet

Alnico Magnet Properties & Grades

GradeBr
[Gs]
Hc
[Oe]
(Bd Hd) max
MGOe
Curie Temp.
[˚F]
Temp. Coe
[%/˚F)
Max. Practical Operating
Temp. [˚F]
Alnico 1 7200 480 1.40 1490 0.016 842
Alnico 2 7000 620 1.60 1490 0.016 842
Alnico 3 6500 530 1.20 1490 0.016 842
Alnico 5 12200 650 5.50 1580 0.011 977
Alnico 6 10500 700 3.50 1580 0.011 977
Alnico 8 8800 1500 5.50 1580 0.014 1022
Alnico 9 10500 1410 9.00 1580 0.014 1022

Br: Residual Induction
Gs: Gauss
Hc: Coercive Force
Oe: Oersted
Bd Hd: Maximum Energy Product
˚F: Degree Fahrenheit

Standard Tolerances (inches);
Rod - Diameter (±0.002), Length (±0.005)
Rectangle - Length & Width (±0.01), Thickness (±0.005)
Ring - Outside Diameter (±0.002), Inside Diameter (±0.02), Thickness (±0.005)

Sintered Alnico Magnets

They have marginally lower magnetic properties, but better mechanical properties, than cast Alnico. Their fine grain structure results in highly uniform flux distributions and mechanical strength. So they are suited for applications requiring short magnets.

alnico magnets

sintered alnico magnets

custom sintered alnico magnet

See table below for grades and properties of cast Alnico magnets.

Build Your Custom Magnet

Sintered Alnico Magnet Grades & Properties

GradeBr
[Gs]
Hc
[Oe]
(Bd Hd) max
MGOe
Curie Temp.
[˚F]
Temp. Coe
[%/˚F)
Max. Practical Operating
Temp. [˚F]
SAlnico 2 7000 620 1.55 1490 0.008 842
SAlnico 3 5800 1130 2.20 1580 0.011 842
SAlnico 5 11000 600 4.25 1634 0.009 842
SAlnico 6 10000 710 3.50 1562 0.011 842
SAlnico 8 8800 1530 5.25 1562 0.011 842
SAlnico 8HC 7000 1750 4.13 1580 0.011 842

Br: Residual Induction
Gs: Gauss
Hc: Coercive Force
Oe: Oersted
Bd Hd: Maximum Energy Product
˚F: Degree Fahrenheit

Standard Tolerances (inches);
Rod - Diameter (±0.002), Length (±0.005)
Rectangle - Length & Width (±0.01), Thickness (±0.005)
Ring - Outside Diameter (±0.002), Inside Diameter (±0.02), Thickness (±0.005)

Magnetism Direction Options

  • Square and rectangular Cast or Sintered Alnico magnets can be magnetized with two poles ("N" & "S") thru the length, width, thickness and with multiple poles.
  • Round Alnico magnet can be magnetized with two poles ("N" & "S") the thickness, diametrically and with multiple poles.
  • Ring Alnico magnet can be magnetized with two poles ("N" & "S") thru the thickness, diametrically and with multi poles. Contact us for magnetism direction of irregular shapes.
Request a Quote