Introduction of Alnico magnets
Alnico is an alloy produced by mixing aluminum, nickel and cobalt with certain addition of other metals like copper, iron and titanium. Capable of producing a strong magnetic field, it has excellent linear temperature characteristics and has wide industrial applications.
Alnico magnets are of different types depending upon the processing techniques and applications. Alnico's are popular alloys of aluminum, nickel, cobalt with a certain tint of iron. These magnets are powerful permanent magnets which can be carved into various shapes and sizes and then used in various applications.
The bar alnico has the following characteristics:
Alnico bar magnets have good thermal stability and are very suitable for high heat applications.
They have maximum working temperature which varies between 975 degrees to 1020 degrees.
Since they are hard and brittle, they cannot be subjected to conventional machining.
As compared to ceramics they have high residual induction and energy product.
If compared to ceramics and rare earth materials they have low coercive force.
Casting or sintering process is applied for making alnico magnets. The first step involves the pouring of molten metal alloys into molds. Later it is passed through various heat cycles. The resultant magnets have a rough surface which after machining gives a glossy look.
Sintered magnets are produced by compacting fine alnico powder in a press, and then sintering the compacted powder into a solid magnet.
Alnico magnets can only be magnetized only in the field having magnetizing fields of about 3 kOe. Since these magnets have low coercivity they must be protected from the adverse repelling fields as this could partially demagnetize the magnets.
After the tolerance magnetizing is effected. As alnico magnets are brittle, they must be protected from hard blows and handled with care. It should be magnetized in a proper magnetic field and must be prevented from the repelling fields as it is prone to demagnetization.
Rev. Recoil Permeability
Saturation Field Strength kOe
Temp.Coefficient of Hc
Alnico magnets have applications in the following areas:
Electric guitar pickups
Automotive and electronic sensors
Hall effect sensors