Permanent Magnets – The Most Popular Magnet Choice

There are three main types of magnets, permanent magnets, temporary magnets and electromagnets.  Of these three types, permanent magnets are the ones the average person is most familiar with.  A good example of a common, everyday permanent magnet is a fridge magnet. 

Permanent magnets are considered permanent because once they are magnetized they keep their level of magnetism. A permanent magnet is an object made from a material that is magnetized and it creates its own persistent magnetic field. 

Permanent magnets can be created in almost every possible shape.  A good permanent magnet should produce a high magnetic field with a low mass.  In addition, when you are looking for qualities of a good permanent magnet you want to ensure the magnet is stable against the influences that can demagnetize it.

There are a number of different types of permanent magnets and each type has different characteristics and properties.  What differentiates these permanent magnets includes:

·         How easily they can be demagnetized

·         How strong they are

·         How their strength changes depending on the temperature

Types of permanent magnets include:

·         Neodymium

·         Samarium-cobalt

·         Alnico

·         Ceramic (also known as ferrite)

Neodymium and samarium-cobalt magnets are classified as rare earth magnets.  Rare earth magnets are permanent magnets that produce the largest magnetic flux with the smallest mass. These magnets are known for being the strongest of all the permanent magnets and are difficult to demagnetize.

Alnico’s name is derived from its components.  Alnico is made of aluminum, nickel and cobalt.  This type of permanent magnet is not easily affected by temperature, however it is easily demagnetized.

Finally, ceramic or ferrite magnets are perhaps the most popular type of magnet, mostly because of their flexibility. Ceramic magnets are flexible and often thin, meaning that they can be bent and moved in a number of different ways, making them excellent choices for advertising and marketing purposes. Ceramic magnets are fairly strong and not easily demagnetized, however their strength varies greatly according to the temperature.

The uses of permanent magnets vary greatly, including:

1.    Mechanical applications rely on the attractive and repelling force of the magnet. Such applications include:

·         Magnetic separators, magnetic holding devices

·         Magnetic torque drives

·         Magnetic bearing devices

2.    Electrical energy applications rely on using the magnetic field of a magnet to convert mechanical energy into electric energy. Such applications include:

·         Generators and alternators

·         Eddy current brakes

3.    Mechanical energy applications rely on using the magnetic field of a magnet to convert electrical energy to mechanical energy. Such applications include:

·         Meters

·         Motors

·         Speakers

·         Relays

4.    Applications that are meant to direct, shape and control electron and ion beams do so using a magnet’s magnetic field.  Such applications include:

·         Ion Pumps

·         Cyclotrons

·         Cathode-ray tubes

Permanent magnets are the most commonly known magnet and are used in a variety of products and environments.  When choosing a permanent magnet you want to consider its strength, performance in temperature and whether it is easily demagnetized.