Types and Uses of Permanent Magnet

Introduction

In general, magnets describe any materials that can attract ferromagnetic objects. These ferromagnetic objects include iron, nickel, cobalt, and so many others. Magnets produce magnetic fields, which are responsible for their ability to attract ferromagnetic objects. Although magnetic fields are invisible, their presence can be detected via the magnetic force they exert.

Permanent magnets are objects created from materials that have been magnetized. They are not easily demagnetized, and they can generate their magnetic field. Permanent magnets can be found all around our environment. They come in different types and have various uses.

Types of Permanent Magnet

Permanent magnets are usually grouped based on the materials from which they are made or the methods used in making them. The four most common types include Neodymium (NdFeB) magnets, which are known for their strong magnetic properties, Samarium Cobalt (SmCo) magnets, valued for their resistance to high temperatures and corrosion, Alnico magnets, offering excellent magnetic stability, and Ferrite magnets, which are cost-effective and widely used in everyday applications.

--Ferrite Magnet

Ferrite magnet is also known as a ceramic magnet. It is usually composed of iron oxide mixed with barium or strontium carbonate. The advantage of this type of magnet is that it is less expensive to create than most other types of magnets because the materials needed to form it are not costly. This magnet is rather brittle and has a low magnetic strength. However, it is highly resistant to corrosion. Ferrite magnet is available in grades 1,5,and 8. Each grade has a different magnetic strength.

--Alnico Magnet

As the name implies, this type of permanent magnet is made from aluminum (Al), nickel(Ni), and cobalt(Co). However, little quantities of other elements are added when producing Alnico magnets to improve their properties. It is highly resistant to corrosion and is stable even under high temperatures. This type of permanent magnet is produced by sintering and casting. Sintering gives Alnico magnet its high mechanical strength.

--Samarium Cobalt Magnet

Samarium Cobalt permanent magnet is made from samarium cobalt, which is a rare earth magnet. This magnet is highly resistant to corrosion, as well as temperatures of up to 300°C. It has a high coercive force and is used for high-energy products. Despite all of this, this type of permanent magnet is expensive and very brittle. Therefore, it is rarely used except in appliances that are subjected to high temperatures.

--Neodymium Magnet

Despite its similarities to the samarium cobalt magnet, neodymium magnet is less resistant to corrosion except when coated. It also has less resistance to high temperatures and low mechanical strength with a range of up to 50MGOe. The material used for the production of this type of magnet is quite costly. For this reason, they are primarily used selectively.

Table 1 Most Common Types of Permanent Magnets

Uses of Permanent Magnets

Permanent magnets are commonly used in industries such as electronics, automotive, energy, aerospace, medical devices, and manufacturing. They play key roles in electric motors, generators, sensors, magnetic separators, and magnetic resonance imaging (MRI) systems.

1. Microphones: Permanent magnets are essential in microphones, as they help convert sound into electrical signals through the movement of a coil in a magnetic field. 
2. Permanent Magnet Motor: Permanent magnets attached to a motor's rotor convert electrical energy into mechanical energy by interacting with a coil in a magnetic field. 
3. Permanent Magnet Generator: Also called a permanent magnet alternator, it converts mechanical energy into electrical energy through the repulsion between two permanent magnets, driving a turbine. 
4. Jewelry: Permanent magnets are used to clasp jewelry securely by attracting ferromagnetic materials. 
5. Sensors: Permanent magnets activate Reed Switch sensors by closing the switch when in contact with a magnetic field. 
6. Magnetic Locks: Permanent magnets are key in magnetic locks, securing doors without the need for electricity and providing tamper resistance. 
7. Magnetic Resonance Imaging (MRI): MRIs use strong permanent magnets to scan internal organs without surgery. 
8. Screwdriving: Permanent magnets in screwdrivers hold screws in place, making the task easier and faster.

Conclusion

Permanent magnets are one of the most versatile and valuable materials in existence. Given the many high-end uses of permanent magnets, it makes perfect sense to invest in them if they are essential to or help improve your business processes. For more information, please check Stanford Magnets.