Alnico Magnet Basics information

1. Price list of stock sizes:
Alnico Plugs
Alnico Channel Horseshoes
Alnico Bars
Alnico Horseshoes
Alnico Holding Magnets
Alnico Rods
2. Alnico Magnet Basics information:
Made from aluminum, nickel, cobalt, copper, iron and sometimes titanium.
They can be either cast (poured) or sintered (pressed and baked).
They are often used in sensor applications because of their long feild depth.
They are supplied “as cast” or ground on selected surfaces. An as cast surface will look brown / grey / red. A ground surface will look shiny like Nickel.
The Alnico horseshoe shape, used long ago, has become an icon for magnets, even though this shape is increasingly replaced. Alnico horseshoes can often be replaced by ceramic assemblies to save money.
The most common grades of alnico are 5 & 8.
The optimum geometry for alnico is unique among magnets. The length is best to be about 4 times the diameter. Magnetized through the length.
Custom sizes available in 3-4 weeks. Stock sizes and price list available upon request by E-mail.
3. Engineering Information:
CAST ALNICO
Cast alnico is 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 and isotropic. This orients the material to take on maximum magnetic field is called isotropic. After heat treatment and cooling, the material can be ground to specific tolerances and then magnetized.
ATTRIBUTES OF CAST ALNICO
Size parameters range from 1 ounce to about 70 pounds
Will cast to a variety of shapes and sizes
SINTERED ALNICO
Sintered alnico is made from a powdered mixture of ingredients that are pressed in to a die under tons of pressure, sintered in a hydrogen atmosphere and then cooled either within a magnetic fielded or without (an isotropic vs. isotropic ).
ATTRIBUTES OF SINTERED ALNICO
Size parameters range from about one ounce of material up to one cubic inch
Pressed to close tolerances/minimal grinding to finish
Mechanically strongest of alnicos
ATTRIBUTES OF BOTH CAST AND SINTERED ALNICO
very temperature stable, great for high heat applications
Maximum working temperature 975�-1020�F
May be ground to size
Does not lend itself to conventional machining (hard & brittle )
High residual induction and energy product compared to ceramic material
Low coercive force compared to ceramic and rare earth materials (more subject to demagnetization )
Most common grades of alnico are 5 & 8
APPLICATIONS OF ALNICO MAGNETS
Magnetos, separators, sensors, electron tubes, traveling wave tubes, radar, holding magnets, coin acceptors, clutches and bearings, motors, relays, controls, generators, receivers, telephones, microphones, bell ringers, guitar pickups, loudspeakers, security systems, cow magnets, distributors.
TYPICAL MAGNETIC & PHYSICAL PROPERTIES OF ALNICO MAGNET MATERIAL
Anisotropy Alnico
Density

Maximum energy Product BH(max)
Residual induction Br
Coercive Force Hc
Intrinsic Coercive Force Hci
Maximum Operating Temperature
Curie Temperature
ibs/in�
g/cm�
MGO
Gauss
Oersteds
Oersteds
F�
C�
F�
C�
Alnico5(cast)
0.264
7.3
5.5
12800
640
640
975
525
1580
860
Alnico8(cast)
0.262
7.3
5.3
8200
1650
1860
1020
550
1580
860
Alnico5(sintered)
0.250
6.9
3.9
10900
620
630
975
525
1580
860
Alnico8(sintered)
0.252
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4.0
7400
1500
1690
1020
550
1580
860
TOLERANCES
Unless specified otherwise, our tolerances on alnico material meet and often exceed Magnet Materials Producers Association (MMPA) standards. For unfinished surfaces ( as cast) the following tolerances apply :
0-1″ �.016 1-3″ �.031 3-5″ �.047
5-7″ �.062 7-9″ �.078 9-12″ �.094
Finished surfaces are normally ground to �.005
MAGNETIZING & 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 can chip or break if dropped on a hard surface. Also, because it has a low resistance to demagnetization, it attracting each other, or with a steel keeper.
MACHINING
Alnico is a very hard and brittle material and does not lend itself to conventional machining. The Magnet Source ™ employs experienced machinists and the proper equipment to grind alnico to its required dimensions .

Sintered Al-Ni-Co Magnetic Characteristics:
Grade
Oriented
Br
(KGs)
Hc
(KOe)
Hci
(KOe)
(BH)max
(MGOe)
CurieTemp
C : F
MaxOpTemp
C : F
Alnico 2
Isotropic
7.1
0.55
0.55
1.4
860
540
Alnico 5
Anisotropic
10.8
0.60
0.60
3.8
860
540
Alnico 6
Anisotropic
9.4
0.79
0.80
2.9
860
540
Alnico 8
Anisotropic
7.2
1.50
1.69
4.0
860
540
Cast Al-Ni-Co Magnet Characteristic:
Grade
Oriented
Br
(KGs)
Hc
(KOe)
Hci
(KOe)
(BH)max
(MGOe)
CurieTemp
C : F
MaxOpTemp
C : F
Alnico1
Isotropic
7.2
0.47
0.48
1.4
860
540
Alnico 2
Isotropic
7.5
0.56
0.58
1.7
860
540
Alnico 5
Isotropic
7.0
0.48
0.50
1.35
860
540
Alnico 5
An isotropic
12.5
0.64
0.64
5.5
860
540
Alnico 5-7
An isotropic
13.5
0.74
0.74
7.5
860
540
Alnico 6
An isotropic
10.5
0.78
0.80
3.9
860
540
Alnico 8
An isotropic
8.2
1.65
1.65
5.3
860
540
Note: The grades listed are typical for the industry. If you need special characteristics then we have other grades available.

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