Permanent Magnets: Properties and Uses of Neodymium Magnets

Neodymium magnets are the most powerful types of magnets. They’re extremely versatile and find very wide applications in our world today. Ranging from smartphones and electrical motors to medical science and renewable energy, neodymium magnets serve several amazing purposes today. 

Neodymium magnets are permanent magnets, and this means that their magnetic effect is always on. They can be found in crafts and jewelry used in the home, as well as in the sophisticated technology used in industrial manufacturing processes. Neodymium magnets have played an essential role in the advancement of several industrial processes over the past 3 decades. 

In this article, we’ll look at the properties and applications of Neodymium magnets in our world today. 

Physical Properties of Permanent Magnets

Most permanent magnets are inherently brittle and are not ideal for use as structural components. Parameters like dimensions and tolerances may vary from one manufacturer to another but most of them often produce magnets to the tolerance of +/- 0.1mm for all dimensions quoted. 

Permanent magnets can be any of alnico, samarium cobalt, ferrite, flexible rubber, and neodymium — the 5 types of permanent magnets, with neodymium magnets being the strongest among them. 

Particularly, Neodymium magnets come in many shapes, including bars and discs, standard rings, custom shapes like trapezoid, arc, and miter. Permanent magnets are usually coated to improve their performance. For instance, neodymium magnets, for example, are the strongest permanent magnets available in the world. However, they are the most successful to corrosion, as a result of their high iron content.

For this reason, they are always made with nickel, epoxy, PTFE (Teflon), rubber, gold, and chrome coatings. 

Uses Of Neodymium

1. Hard disk drives

Hard disk drives record data by alternatively magnetizing and demagnetizing a thin film of ferromagnetic material on a disk. Each disk has separate tracks and sectors, with each sector having many little separate magnetic cells. These magnetic cells are magnetized by the read/write head of the drive when data is written to the drive. 

2. Audio equipment: microphones, headphones, and loudspeakers

Sound devices, microphones and speakers especially, are made with permanent magnets like neodymium magnets. Speakers consist of a current-carrying coil that converts electrical energy into mechanical energy and the sound.

3. Dentures

Tiny neodymium magnets have an increased resistance to corrosion when they are coated, so they can serve as attachments in corrective devices. They are also used to hold replacement dentures together when several teeth are missing.

4. Magnetically coupled pumps

Magnetically coupled pumps have a motor-driven shaft with an attached ring of powerful permanent magnets along with another smaller ring of magnets attached to another shaft, which is connected to the impeller. The impeller sits within the larger ring of magnets. Usually, when the motor turns the driveshaft and one of the rings of magnets, a magnetic field is generated and turns the other set of magnets which in turn, powers the impeller.

5. Door catches

Neodymium magnets are used to build magnetic door catches in public buildings. Strong neodymium magnets can easily hold the weight of a door.

6. Motors and generators

Electric motors work based on a combination of an electromagnet and a neodymium magnet that converts electrical energy into mechanical energy. A generator operates in a reverse manner. It converts mechanical energy into electric energy by moving a conductor through a magnetic field.

7. Jewellery

Tiny permanent magnets are used in making jewellery and for jewellery clasps. Counter-bored neodymium magnets often provide a secure hold, especially with its strong magnetic force.

8. Bearings

Magnetic bearings work based on the concept of magnetic levitation. They provide support to moving parts of machines. Passive magnetic bearings consist of permanent magnets such as neodymium magnets. Active magnetic bearings, on the other hand, use electromagnets.

9. MRI scanners

Many ‘open’ MRI scanners used in hospitals today use large neodymium magnets. MRI scanners work by inducing a large magnetic field in the human body. This magnetic field aligns the protons in the body in its direction. The images are produced by directing radio frequency waves at the body.

10. ABS (anti-lock braking) system sensors

Passive ABS sensors consist of neodymium magnets wrapped inside copper coils. A sensor placed close to the ABS reluctor ring aids to induce voltage in the copper wire as the ring rotates.

Other applications of Neodymium Magnets can be found in: 

• Levitation devices
• Lifting machinery
• Reed switches
• Crafts and model-making
• DIYs and home improvement
• Hanging of artwork
• Point of sale displays