Alnico Magnets: How do they work?
Alnico Magnets: How do they work?
Although Alnico magnets have increasingly been replaced by the rare-earth magnets, they are still common in many products, such as relays, testing equipment and guitar pick-ups. They are particularly critical in electro-permanent magnetic chucks and lifting equipment. Keep reading to learn more about alnico magnets, how they work, and their applications.
What are Alnico Magnets?
An alnico magnet is a type of magnet designed using cobalt, nickel, and aluminum. The magnets come in isotropic, anisotropic, non-directional, and mono-directional types. When magnetized, they provide up to 17 times the magnetic strength of magnetite, the naturally occurring magnets.
Alnico magnets come with low-temperature coefficient and also make it possible to calibrate for high-residual induction for high-temperature applications, such as 930°F or 500°C. Also, they are the preferred magnets where high levels of corrosion resistance are desirable and in sensors.
The first category of magnets was the naturally occurring loadstones, which explorers used to identify the earth’s North Pole. Alnico magnets were discovered around 1931 when a Japanese, T. Mishima, established that a combination of aluminum, iron, and nickel had a high coercivity of up to 32KA/M, which was double that of magnets of the time.
How are Alnico Magnets Designed?
Alnico magnets are developed by sintering a mixture of cobalt, nickel, and aluminum. Titanium, copper, and iron might be added to enhance the magnetic force. The grade of the magnet depends on the chemical composition of individual materials. The method of magnet production depends on the weight, size, and expected final use. Very large alnico magnets are made through casting, while sintering is preferred for the smaller models. Here are the main steps involved in making an alnico magnet:
- Casting or heating.
- Fettling.
- Heat treatment/ hardening.
- Finishing grinding.
- Testing.
- Coating.
- Magnetizing.
Uses of Alnico Magnets
Like other magnets, alnico magnets can take any shape, including cylinders which are common in motor applications, horseshoe, pot, and ring. Now that you know how the magnets are produced and the main shapes, it is time to look at their applications. Where are alnico magnets used?
Alnico magnets are preferred for applications where temperatures can be pretty high. They are also the go-to option where strong permanent magnets are required, such as loudspeakers, electric motors, and microphones. Here are other uses of alnico magnets:
- Motors: Alnico rotor magnets are made with a number of poles that feature alternating polarity. A hole in the rotor makes it possible for the magnets to be mounted on the shafts. They are excellent for dynamos, synchronous motors, and turbine generators.
- Cow magnets: In the agricultural sector, cow magnets are used to help save the lives of animals, especially cows that love eating dirt, nails, and baling wires. If these items get their way into the stomach of a cow, they can result in “hardware disease.” The magnets are lodged in a cow’s second stomach to help attract stray metals.
- Speakers: Alnico magnets are a recommended category of magnets for speakers because they make it easy to tune the magnetic field for maximum acoustic performance.
As you can see, alnico magnets have a number of uses, and it is important to select the preferred type depending on the targeted application. If you are buying an item with inbuilt magnets, insist that they are designed with alnico magnets. Furthermore, it would be best if you only bought alnico magnets or related equipment from top brands for better performance.