Share this article

Concept of Neodymium Magnets

Neodymium magnets are among the strongest commercially available rare earth magnets, capable of lifting things several times their weight. They are extensively utilized in engineering, manufacturing, education, research, and industry as positioning, pulling, and clamping components.

What exactly are Neodymium Magnets?

Neodymium magnets are rare earth magnets. They are permanent magnets, which means they will endure for many years. They are the most widely used rare earth magnets, composed of neodymium, boron, and iron alloy. They are also said to be the strongest form of permanent magnet commercially accessible to consumers and are one of the cheapest options for the typical individual. There are many uses for Neodymium magnets, but they have grown increasingly popular because of their power and low cost, which takes us to our subject of discussion in this article. Continue reading to learn all you need to know about Neodymium Magnets.

History

General Motors & Sumitomo Special Metals created neodymium magnets in 1982 after developing the Alloy NdFeB, which contains neodymium, iron, and boron. In 1982, General Motors and Sumitomo Special Metals developed the Nd2Fe14B compound in response to the escalating cost of samarium-cobalt magnets (SmCo) permanent magnet raw material. As a consequence, they developed a low-cost, high-performance neodymium magnet. Despite being collaboratively developed, General Motors and Sumitomo Special Metals used separate production procedures. General Motors produced neodymium magnets in powdered bonded form, and Sumitomo used the sintering manufacturing process.

Sumitomo Special Metals designs, produce, and licenses full-density sintered Nd2Fe14B magnets to other firms. Hitachi currently possesses over 600 patents related to Neodymium magnets. Because of its ample supply of rare earth ores, China has surpassed the United States as its most prominent producer of Neodymium magnets. In 2010, the world produced 129,000 metric tons of rare earth elements, with little non-Chinese contribution. In other words, most of these rare earth elements were made in China.

Neodymium Magnet Strength

The strongest commercially available magnets are neo magnets. Their pulling force is often ten times greater than typical ceramic (ferrite) magnets.

These strong magnets have a high coercivity and a high maximum energy product. In other words, they generate a dense magnetic field that can withstand decay.

The Manufacturing Process and the Power of Magnets

Sintering and bonding are the two primary methods for producing neodymium magnets. Each relates to a different production method, which is explained further below:

  • Sintering involves pressing raw magnetic materials into blocks before subjecting them to a complex heating process. The block will then be trimmed to the desired form and coated for corrosion protection.
  • Bonding is the process of making magnets by combining raw materials and binding them with epoxy before pressing them into a die cavity and curing them with heat.

Strong neodymium magnets are frequently produced by sintering since sintered kinds are about twice as strong as bonded equivalents. On the other hand, Bonded NIB magnets are more adaptable and cost-effective. This is because bonded neodymium magnets may be fashioned into various sizes and forms as needed, while sintered magnets are limited to relatively basic designs due to their brittle nature.

Properties

Grades

Are you perplexed by the various letters and numbers in a Neo grade’s name? We shall describe the differences in neodymium magnet grades here.

Everything begins with the letter N; neodymium magnet names start with “N” for neodymium. The following is more technical since it reflects the magnet’s maximal energy product in Mega-Gauss Oersteds (MGOe). This is the fundamental determinant of a magnet’s strength. The greater the total energy product value, the stronger the magnetic field generated by the neodymium magnet in a given application.

The grades commonly available for purchase vary from N30 to N52 since lower grades are no longer produced.

We do not compromise on quality at ROBO Magnetic, and the bulk of our magnets ranges from grade N30 to N30EH, making them more magnetic than many grade neodymium magnets. Our Neodymium magnets grade provides good performance at a low cost.

One or two letters may be slapped onto the end of a grade. These letters establish the temperature rating and signify the highest operating temperature that the magnet can endure before it permanently loses its magnetic. These values should always be a guideline since other parameters like size and shape influence a magnet’s performance at high temperatures. Visit our Neodymium Magnets Grade Page for additional information.

All of our Neodymium magnets meet REACH and ROHS requirements. They contain no SVHC and are manufactured following ISO9001 and ISO14001 Quality Control Standards. NdFeB Neodymium magnets are commonly available in standard and bespoke forms such as blocks, rings, discs, arcs, triangles, spheres, trapezoids, etc. We also produce NdFeB magnet assemblies.

Click here for more information on grades and their magnetic information.

Magnetic Characteristics

Remanence

When an external magnetic field is withdrawn, the magnetization left behind in a magnetic substance is remanence, residual magnetism. or remanent magnetization. When a Neodymium magnet is “magnetized,” it exhibits remanence. Magnetic remanence supplies magnetic memory in magnetic storage devices and is employed as a source of knowledge about the previous Earth’s magnetic field. In this situation, Neodymium magnets are graded according to their magnetic field strength as assessed by remanence (Br). As a result, they are thought to have more remanence.

Coercivity

Coercivity, also known as a magnetic coercive force, or coercive field, measures a ferromagnetic material’s capacity to endure an external magnetic field without demagnetization. Coercivity is commonly measured in either oersted or ampere/meter units and is represented by the symbol HC. The draw force of neodymium magnets is generally ten times that of ceramic (ferrite) magnets. These strong magnets have a high coercivity. In other words, they generate a dense magnetic field that can withstand decay.

Maximum energy output

The maximum energy product is an essential figure of merit in magnetics for the strength of permanent magnet material. It is sometimes abbreviated as (BH)max and is usually expressed in kJ/m3 (kilojoules per cubic meter, for SI electromagnetism) or MGOe (mega-gauss-oersted, in gaussian electromagnetism). MGOe is the same as 7.958 kJ/m3. Neodymium magnets have a high maximum energy product in terms of this amount.

Curie Temperature

The Curie temperature (TC), also known as the Curie point, is the temperature at which some materials lose their permanent magnetic characteristics, which may be replaced (in most instances) by induced magnetism. The Curie temperature was named after Pierre Curie, who demonstrated that magnetism might be lost at a crucial temperature. Neodymium magnets have a lower Curie temperature than other magnet kinds. However, neodymium magnets will hold their charge for a long time if not exposed to high temperatures, shedding as little as 5% every 100 years. Special neodymium magnet alloys, including dysprosium and terbium with higher Curie temperatures, have been produced, enabling them to withstand greater temperatures.

Grade Curier Temp(oF/oC) MaxOp Temp (oF/oC)
N 590/310 176/80
M 644/340 212/100
H 644/340 248/120
SH 644/340 301/150
UH 662/350 356/180
EH 662/350 392/200
AH 662/350 446/230

Surface Treatment and Corrosion Issues

Neodymium magnets are highly porous metal, which allows the irons to oxidize or rust more quickly, particularly in humid circumstances. In contrast, some grades of Neodymium magnets have lately been created with improved oxidation resistance. Corrosion may be avoided in part by adding an appropriate coating or plating. Many various materials may be used to coat neodymium magnets, including nickel, copper, zinc, tin, epoxy, silver, and gold, while nickel is the most typically utilized, and a multi-layer coating process (e.g., nickel-copper-nickel) is also generally employed to make the product more corrosion resistant. A Salt Spray/Salt Fog Test (SST) may be used to test the performance of a coating.

Temperature Effects

Thermal (random) motion exerts additional effort to re-orient the originally aligned (domain atoms) spins, producing demagnetization of the Neo magnet. Depending on the extent of the raised temperature, this demagnetization might be permanent or transitory. Two parameters assess the capacity of a neodymium magnet to resist demagnetization by rising temperature: maximum operating temperature (MaxOpTemp) and Curie temperature, as indicated in the table below for various classes of Neodymium magnets. The magnetic flux of an average N grade Neodymium magnet will permanently lose a percentage of its strength at its maximum operating temperature and all of its magnetic strength at its Curie temperature. Most Neodymium magnets, for example, lose their magnetism above 80/176ºC/ºF. Exceptional grades of Neo magnets with a higher CT (up to 220/428ºC/ºF)) have been created to operate at high temperatures, such as in windmills and hybrid motors. Thus, while selecting neodymium magnets, it is critical to examine which grade is most suited to your demands regarding the operating temperature setting.

Aside from demagnetization induced by increased temperature, another component may contribute to the demagnetization of Neodymium magnets. The magnetic flux of the Neo magnet may stay constant or lose some of its strength depending on the intensity of the demagnetizing field, and this process may be reversible or irreversible. When the demagnetizing area surpasses a threshold value, the magnet’s coercivity, the Neodymium magnet, is demagnetized and re-magnetized based on the direction of the external field.

Hazards & Tips Needing Attention

Neo magnets are the most powerful magnets on the planet, and the powerful force between them may take you by surprise if precautions are not accepted. Please examine this checklist to ensure the correct handling of these magnets and the avoidance of potentially significant physical injury and potential damage to the Neodymium magnets.

  1. Neodymium magnets may collide, squeeze the skin, and inflict severe injuries.

Neodymium magnets will jump and bang together from a few inches to several feet away. If you put your finger in the path, it might get badly pinched or fractured.

  1. Neodymium magnets are fragile, readily shattering and breaking.

Neodymium magnets are fragile and will peel, break, split, or shatter if slammed together, even if they are just a few inches away. They are not as hard as steel despite being formed of metal and covered with a gleaming nickel coating.

Shattering magnets may propel tiny sharp metal fragments into the air at high speeds. Eye protection is advised.

  1. Keep neo magnets out of the reach of all children.

Magnets made by neodymium are not toys. Allow children no access to or play with them. Small magnets may be dangerous if swallowed. Multiple magnets eaten may bind to one other via intestinal walls, causing significant damage and death.

  1. Keep neodymium magnets away from those who have pacemakers.

Strong magnetic fields are generated by neodymium magnets, which may interfere with ICDs, pacemakers, and other implanted medical equipment. Many of these gadgets include a mechanism that deactivates the device in a magnetic field.

  1. Avoid using neodymium magnets near magnetic material.

Magnetic media such as magnetic ID cards, credit cards, cassette tapes, video cassettes, and other similar devices may be damaged by the intense magnetic fields produced by neodymium magnets. They are also capable of causing harm to older TVs, computer monitors, VCRs, and CRT displays.

  1. Avoid using neodymium magnets near your GPS or smartphone.

Magnetic fields interfere with compasses or magnetometers used in air and marine transportation navigation and internal compasses in smartphones and GPS systems.

  1. Avoid contact with neodymium magnets if you are allergic to nickel.

According to studies, a small number of persons are allergic to some metals, including nickel. Redness and a skin rash are common symptoms of an allergic response. If you are allergic to nickel, use gloves or avoid handling nickel-plated neodymium magnets.

  1. At high temperatures, neodymium magnets may become demagnetized.

While magnets have been shown to keep their efficacy at temperatures as high as 80°C (175°F), this temperature may vary based on the magnet’s form, grade, and use.

  1. The dust and powder of neodymium magnets are combustible.

Neo magnets should not be machined or drilled. This substance is very combustible when crushed into dust or powder.

  1. Neodymium magnets are prone to corrosion.

Also, remember that neodymium magnets are prone to corrosion when not properly coated. In the presence of moisture, they may rust or corrode. They may corrode and lose magnetic strength if used underwater, outdoors, or in a damp environment.

Recommendations for Safely Handling Neodymium Magnets

  • Neo magnets should not be drilled or machined.
  • Neodymium magnets will keep their magnetism and integrity for decades when correctly handled, used, and protected.
  • Remember to keep your hands apart while you have magnets in both hands.
  • Seek emergency medical assistance for any significant injuries.
  • To separate magnets, grab the outer magnet, slip it off the stack, and swiftly pull it away.
  • Use eye protection and work gloves (if required) when dealing with magnets.
  • When separating or handling magnets, pay special attention.
  • Work on a surface or metal table so the magnets remain in place and don’t bounce together.

Process Flow

Multiple key manufacturing phases and countless sub-steps create high-quality, high-tech Neo magnets. Hence, each step is critical and a necessary aspect of a highly tuned process.

Incoming Inspection

This phase involves the inspection of raw materials needed for Neodymium magnet manufacturing. The samples are inspected, cleaned, and prepared for alloyed preparation.

Alloy Preparation

Small amounts of additional metals are applied to NdFeB alloy throughout the alloying process to refine and change the microstructure of the final product, boosting its magnetic characteristics and the impact of subsequent procedures.

Melting

Melting and strip casting of alloyed NdFeB is now possible. The products are heated in a vacuum furnace, and then a stream of molten metal is pushed under pressure onto a cooled drum. As a result, it is quickly cooled at 100,000 degrees per second. The rapid cooling creates extremely tiny metal grains, which simplify and improve the impact of the downstream processing. Small grains are also a key component in the production of high-quality magnets.

Milling

Milling grinds NdFeB metal into powder using a high-speed cyclonic inert gas. The metal collides with other metal powder particles within the cyclone. The cyclone automatically classifies particles by size as they pass through the system, resulting in a narrow – and highly desirable – particle size distribution.

The cyclonic airflow automatically separates the particles because various particle sizes have varying aerodynamics. It prevents the material from coming into touch with the walls of the pressure vessel owing to the gas flow pressure and velocity.

Pressing

Before entering the automated press, the powder is maintained in an inert gas environment and handled in glove boxes. The powder is crushed between plates in a mold while subjected to a high magnetic field, forming a material block. The magnetic field aligns the grains such that the magnetic poles stay aligned in the intended direction throughout the remainder of the processing stages.

The magnetic field may be directed in two directions: 1) parallel to the block and 2) perpendicular to the block.

To produce the greatest sintered neodymium magnets, they are typically pushed perpendicular to the block (strongest north-south magnetization)

Sintering & Annealing

The pressed block is taken from the bag and then sintered. Sintering is a technique in which the blocks are heated to just below the melting point of the metal in a furnace. At temperatures over 1000oC, the individual atoms move a lot, allowing the blocks to achieve their full magnetic and mechanical capabilities. The magnetic domains retain their original orientation after sintering. The blocks have reached a total density and shrunk to their ultimate size at this temperature.

Because of the pent-up strains in the metal caused by the sintering action, the blocks are heat-treated again in a step pattern at lower temperatures to alleviate the stresses. The blocks produced are ramped to a high holding temperature for a predetermined time before being ramped down to a lower holding temperature. Once the holding period has been reached, the blocks are gradually cooled to room temperature.

Machining

Because of the above procedures, NdFeB magnets have gained much value. Cutting, machining, and grinding are all done following a precise control plan, and waste is kept to a minimum by design.

Wire cutting is done using extremely tiny wire to reduce incision losses. Close controls throughout the preceding steps reduce machining and grinding. Waste is repurposed and recycled.

Coating

Before leaving the facility, most Neodymium magnets now get a final surface treatment. The standard treatment is a nickel-copper-nickel electroplate, which protects the neodymium magnet against corrosion in most common situations.

For various reasons, some end customers want no coating at all. There are various options for coatings, but nickel is the most common and usually preferred. Our nickel-plated magnets are triple plated with nickel, copper, and nickel layers. This triple coating makes our neodymium magnets much more durable than the common single nickel-plated magnets. Other layer options are zinc, tin, copper, epoxy, silver, and gold. Our gold-plated neodymium magnets are quadruple plated with nickel-copper-nickel and a top coating of gold. Ni+Cu+Ni, Epoxy, Zn, Color Zn, and Passivation are the most ordered coatings. For more information regarding our coating offers, please visit our Coating Page.

Coating Examination

Several metrics, such as pulling force and magnetic field strength, contribute to a magnet’s strength. Each of these elements will need to be tested and quantified.

Magnetizing

Magnetizing is one of the last processes. The material is put within an electric coil and briefly activated to generate a powerful magnetic field. The magnetic field in the magnet continues after the coil is de-energized.

After plating, the completed material is magnetized, which involves putting it within a coil that creates a magnetic field three times stronger than the needed strength of the magnet when an electric current is sent through it.

Final Examination

Magnet material is tested and evaluated practically every manufacturing step, and records of every data point are retained. With such stringent testing requirements, ROBO Magnetic maintains a large inventory of test equipment in-house to maintain and enhance product quality, manufacturing efficiency, and cost. Thorough testing ensures that only high-quality items are supplied to customers.

Storage

Neodymium magnets should be kept in a low-humidity, low-temperature environment. The magnetic neodymium alloy is very powerful and will attract ferrous particles from the surrounding air and surfaces. These particles will gather and appear on the surface of the magnet or package as little “hairs.” Keep the neodymium magnets in tight, clean containers and leave them in their original ROBO Magnetic packing to avoid accumulating dirt. With all spacers in place, the neodymium magnets should keep attracting. Metal shelves with insufficient clearance may cause magnets to leap or move when accessible. Keep magnetic materials away from sensitive electronics, cathode ray tubes (CRT), and magnetic storage media. Neodymium magnets of different alloys may need to be buffered from each other due to demagnetizing effects.

What Sets Neodymium Different From Other Magnets?

Neodymium magnets are rare-earth magnets that include neodymium, iron, and boron. In contrast, ordinary magnets are typically ceramic (or ferrite) magnets that contain iron(III) oxide and are used for everyday tasks. As a result, the primary factor differentiating between a neodymium magnet and a conventional magnet is the essential components of these magnets. The characteristics of neodymium and ordinary magnets vary significantly due to the above composition. Neodymium magnets have very high remanence, coercivity, and energy products, while regular magnets have low remanence and energy products. However, ferrite magnets are classified into two categories based on their coercivity: hard ferrites and soft ferrites (high and low, respectively). Furthermore, the Curie temperature of neodymium magnets is lower than that of conventional magnets.

Various Shapes And Uses

  • Neodymium Magnet Discs: These Neodymium magnets are precise round disc magnets. They may be inserted into pre-drilled holes.
  • Neodymium Ring Magnets: Neodymium ring magnets are used for magnetic operations that need a center hole. They feature holes in the middle and are circular.
  • Neodymium blocks: These forms are used in applications requiring straight-edged bars.
  • Neodymium Cylinder Magnets: These cylindrical magnetic materials are also used in drilled holes.
  • Neodymium Cube Magnets: Can also be used as welding clamps, in remodeling to discover studs, attachment devices, in oil pans to filter out metal chips, and for mounting protective outdoor coverings to automobiles, boats, motorcycles, and other equipment, among others.
  • Neodymium disc/cylinder magnets with countersunk holes
  • Neodymium plate/block magnets with countersunk holes
  • Neodymium arc magnets

How to Buy

ROBO Magnetic provides full-service development as far as Neodymium Magnet is concerned. A wide range of Neodymium magnetic alloys. ROBO Magnetic creates magnetic solutions for a variety of applications. Please request a quote by filling the sheet at ROBO Magnetic contact us page or send an inquiry to sales@robomagnetic.com.

Summary

Neodymium magnets have more remanence, making it possible to attract when their polarity is reversed. It is also the most powerful permanent magnet in its class—with maximum pull strength. These qualities, combined with outstanding properties in other types of magnets (coercive force, permeability), make neodymium magnets useful for many applications. Neodymium magnets are versatile, high-performance magnets used in various applications, ranging from magnetic jewelry to high-tech manufacturing. They have many uses and powerful properties, making them useful for various industrial applications. Due to their extreme strength and durability, these magnets are often used in construction projects, commercial tools and equipment, manufacturing processes, automotive engines, plumbing systems, fastening devices, and just about every machine or technological device you can imagine.

robo_magnetic

Article by

ROBO Magnetic Product Team

We are the manufacturer with 16 years of experience in custom neodymium magnets.

Need A Quote? Get in touch with us directly.

Share this article

0 0 votes
Article Scoring
Subscribe
Notify of
guest
0 Comment
Inline Feedbacks
View all comments