AlNiCo Magnet

AlNiCo magnet is composed of Aluminum, Nickel, Cobalt, and a few transition metals. They have excellent temperature stability, high residual induction, and relatively high energies. AlNiCo magnet may be manufactured in complex shapes, such as horseshoes, which is otherwise not possible with other magnet materials. They represent the most versatile magnets available.


Manufacturing Process


Alnico magnet is manufactured through either casting or sintering processes. Cast magnet is manufactured by pouring a molten metal alloy into a mold and then further processing it through various heat-treat cycles. The resulting magnet has a dark gray exterior appearance, and may have a rough surface. Machined surfaces have a shiny appearance similar to steel. Sintered magnet is manufactured by compacting fine Alnico powder in a press, and then sintering the compacted powder into a solid magnet.


Machining & Tolerance


Alnico magnet is hard and brittle, and prone to chipping and cracking. Special machining techniques must be used to machine this material. The Standard tolerances for Alnico magnet is +/- 0.1mm for ground dimensions, but sticter tolerances are possible if specially required.


Surface treatments


The corrosion resistance of Alnico magnet is considered excellent , and no surface treatments are required. However, Alnico magnet is easily plated if specially required.


Magnetizing & Packing


Alnico magnet requires magnetizing fields of about 3kOe. Because of their relatively low coercivities. Alnico magnet should be packed properly in order to assure that the magnet is not subjected to adverse repelling fields, since this could partially demagnetize the magnet.


Cast Alnico 5 is the most commonly used of all the cast Alnicos. This material is used extensively in rotating machinery, meters, instruments, sensing devices, and holding applications, to name a few.

 

                    

 

Magnetic properties of AlNiCo magnet

 

Grade Residual Induction Coercive Force Maximum Energy Product Rev. Temp.Coeff.
Br Hcb (BH)max Br
mT kA/m kJ/m3 Hcj
[Gs] [kOe] [MGOe] %℃
LNG10 600 40 10.00 -0.02
[6000] [500] [1.20] 0.03
LNG12 700 44 12.00 -0.02
[7000] [550] [1.50] 0.03
LNG13 680 48 13.00 -0.02
[6800] [600] [1.63] 0.03
LNG18 900 48 18.00 -0.02
[9000] [600] [2.25] 0.03
LNG37 1200 48 37.00 -0.02
[12000] [600] [4.63] 0.03
LNG40 1250 48 40.00 -0.02
[12500] [600] [5.00] 0.03
LNG44 1250 52 44.00 -0.02
[12500] [650] [5.50] 0.03
LNG52 1300 56 52.00 -0.02
[13000] [700] [6.50] 0.03
LNG56 1300 58 56.00 -0.02
[13000] [720] [7.00] 0.03
LNGT60 1330 60 60.00 -0.02
[13300] [750] [7.50] 0.03
LNGT72 1050 112 72.00 -0.02
[10500] [1400] [9.00] 0.03
LNGT88 1100 115 88.00 -0.02
[11000] [1450] [11.00] 0.03
LNGT36J 700 140 36.00 -0.02
[7000] [1750] [4.5] 0.03
LNGT52J 900 140 52.00 -0.02
[9000] [1750] [6.50] 0.03

 

Physical properties of AlNiCo magnet

 

Grade Modulus of elasticy Ultimate tensile strength Density Electrical Resistivity Curie temperature Hardness (Rockwell C ) Temp.Coeff.of Br
Alnico 5, Cast 10,500 psi 5,400 psi 7.3 g/cm3 47 µ-ohm-cm/cm2 860-900℃ 50 From -0.02 to -0.022% / ℃
Alnico 6, Cast 45,000 psi 23,000 psi 7.3 g/cm3 50 µ-ohm-cm/cm2 860-900℃ 50 From -0.02 to -0.022% / ℃
Alnico 8, Cast 30,000 psi 10,000 psi 7.3 g/cm3 53 µ-ohm-cm/cm2 860-900℃ 55 From -0.025 to -0.028% / ℃
Alnico 2, Sintered 70,000 psi 65,000 psi 6.8 g/cm3 68 µ-ohm-cm/cm2 810-850℃ 45 From -0.03 to -0.032% / ℃
Alnico 5, Sintered 55,000 psi 50,000 psi 6.9 g/cm3 50 µ-ohm-cm/cm2 860-900℃ 45 From -0.02 to -0.022% / ℃
Alnico 8, Sintered 55,000 psi 50,000 psi 7 g/cm3 54 µ-ohm-cm/cm2 860-900℃ 45 From -0.025 to -0.028% / ℃