Alnico Magnets: Manufacture, Properties and Applications

Published: 2023-04-19 09:44:17 • Daniel Gårdefelt

Alnico magnets are made up of aluminum (Al), nickel (Ni) and cobalt (Co), hence their name. Alnico magnets have been widely used in a variety of industries for decades due to their known temperature stability and magnetic strength. This article will discuss the manufacturing process, properties and applications of Alnico magnets.

The history of Alnico.
In the 1930s, researchers at the Tokyo Institute of Technology in Japan discovered the unique magnetic properties of Al-Ni-Co alloys, leading to the development of Alnico magnets. During World War II, the demand for potent permanent magnets led to further research and performance improvements for Alnico magnets.

The manufacture of Alnico magnets involves several phases, including preparation of raw materials, melting of alloys, casting or sintering, and finishing.

1. Preparation of the raw materials Alnico magnets are mainly composed of aluminium, nickel and cobalt, with smaller amounts of iron, copper and titanium. To obtain the desired alloy composition, these elements are carefully measured and mixed.

2. Alloy melting: The combined elements are melted at temperatures above 1,500°C in an induction furnace. The molten alloy can then be cast or sintered.

Alnico magnets can be made by either casting or sintering. During the casting process, molten alloy is poured into a mold and allowed to cool, producing a solid magnet of the desired shape. In the sintering process, the powdered alloy is compressed and heated in a controlled atmosphere until the particles fuse together.

3. Finishing: After the completion of the casting or sintering process, the Alnico magnet undergoes various finishing processes, such as honing, cutting or machining, to achieve the desired dimensions and tolerances. In some cases, a surface treatment or coating may be used to improve the appearance or corrosion resistance of a magnet. However, due to their composition, Alnico magnets naturally resist corrosion, eliminating the need for protective coatings or plating.

Features and benefits of Alnico magnets

1. Excellent temperature stability: Alnico magnets are one of the most heat-resistant magnetic materials, making them suitable for use in applications that require extreme temperature conditions.

2. Different Shapes and Sizes: The casting process allows the manufacture of Alnico magnets in a variety of shapes and sizes, allowing for greater design versatility.

Applications of Alnico Magnets:

1. Automotive: Alnico magnets are used in a variety of sensors, actuators and electric motors for vehicles.

2. Aviation and Defense: Alnico magnets are used in aircraft navigation and communication systems.

3. Electronics: Alnico magnets are essential to the operation of many electronic devices, such as speakers, microphones and magnetic switches.

Alnico magnets are used in medical equipment including magnetic resonance imaging (MRI) instruments and dental devices.

4. Industrial: Alnico magnets are used, among other things, in motors, generators and magnetic separators.

Alnico magnets are an indispensable and versatile type of permanent magnet, with exceptional thermal stability and high corrosion resistance. Their distinctive properties make them suitable for a wide range of applications in a variety of industries, including the automotive, aerospace, electronics, medical and industrial sectors.

The manufacturing process for Alnico magnets, which involves alloy melting, casting or sintering, and refining, allows for the production of magnets in a variety of shapes and sizes. In addition, the ability of Alnico magnets to maintain their magnetic properties in high temperature environments makes them an ideal choice for applications exposed to extreme temperatures.