Product Overview

Description

An Introduction to Alnico Magnets

Alnico is an alloy containing Aluminium (Al), Nickel (Ni), Cobalt (Co) hence its name Alnico. But Alnico actually contains more than just these three elements. It also contains Iron and Copper with some versions also containing Titanium and even Niobium (the Titanium versions were sometimes called Ticonal, derived from the elements TiCoNiAl). Alnico magnets were developed in the 1930’s and were the first “Real” performance permanent magnets (the first “magnets”, called magnetic steels, were quickly replaced by the vastly superior Alnico).

Alnico is produced by either a sintering method or, more commonly, a casting method. The as cast or as sintered shape is acceptable for many applications but surfaces may need to be ground for a smoother surface finish. The as cast look has darkened edges with a slightly rough texture (due to the sand mold edges); a machined face of an Alnico magnet has a bright silvery metallic surface and is usually extremely smooth as it is often precision ground.

There are 29 grades of Alnico (17 cast grades, 10 sintered grades, 2 bonded grades). Alnico has many trade names used for naming the grades such as Columax, Alcomax 3SC, Alni, Hycomax, Ticonal, etc. China has given them names starting with the letters LNG followed by a number to try to give some clarity but this is not widely utilised. Most people still know Alnico under its more common grade names such as Alnico 5, Alnico 8, Alnico 9, Alnico 5DG, Alnico5-7, Alnico8HC, Alnico 6, Alnico 2, Alnico3, Alnico 500, Alnico 400, Alnico 600 and Alnico 700, etc.

Most Alnico magnet grades are anisotropic (they can only be magnetised in a single axis / direction – they are the more powerful magnet grades of Alnico. The others are isotropic (they can be magnetised in any direction or directions) – they are weaker but offer more design and performance flexibility.

The most commonly used Alnico is Alnico 5. But care should be used when using this terminology. There are 4 version of cast Alnico 5 plus a single version of sintered Alnico 5 (it should be noted that sintered Alnico and cast Alnico have slightly different magnetic and mechanical properties). Therefore a request for Alnico 5 could result in different performing magnets due to accidental interpretation of the grade requirement.

Applications

Examples of applications using Alnico Magnets

• Very high temperature applications
• MRI
• Medical Applications
• Cow Magnets
• Magnetic Pump Couplings
• MRI and NMR
• TWT (Transverse Wave Tube), Electron tubes, radar, traveling wave tubes
• Pot Magnets
• Loudspeakers
• Meters
• Motors
• Generators
• Automotive, Aerospace and Military sensors
• Electro-Acoustic pick-ups (e.g. guitar pick-ups)
• Switches
• Hall-Effect devices
• Mass Spectrometers
• Headphones
• Dentures
• Magnetrons
• Loudspeakers
• Magnetic Pump Couplings
• Door Catches
• Radar