N40 Neodymium Magnets: A Comprehensive Guide

N40 neodymium magnets are distinct rare earth magnets graded based on their maximum energy product. This classification of neodymium magnets boasts a BHmax of 40 MGOe, which makes them some of the sturdiest permanent magnets.

N40 Neodymium Magnets
N40 Neodymium Magnets

Advantages of N40 Magnet

N40 magnets offer numerous advantages compared to other grades of NdFeB magnets. Here are the most impactful advantages:

High Magnetic Strength

N40 neodymium magnets are graded according to their magnetic strength, which is impressively 40 MGOe. This is relatively stronger than other grades of neodymium magnets as well as other rare earth magnets. Owing to their sturdy magnetic power, N40 magnets are highly utilized in applications demanding powerful magnetic forces.


Equipped with a comparatively high magnetic strength, N40 magnets suit various applications perfectly. They can be produced in varying sizes and shapes and this further adds to their versatility. They are prominently employed in different fields ranging from consumer electronics to medical equipment.


Neodymium magnets are considerably economical especially when compared to samarium cobalt magnets. The N40 magnet grade in particular offers a great balance between cost and performance. This elevates its suitability for applications with budgetary constraints.

Thermal Stability

With a curie temperature of up to 350 °C and a maximum operating temperature of approximately 80 °C, N40 NdFeB magnets exhibit a relatively high tolerance to temperature fluctuations.

Prolonged Lifespan

All grades of neodymium magnets are generally permanent rare earth magnets. This quality translates into decades of impeccable service. The N40 magnets can withstand extreme temperature changes and this elevates their ability to withstand demagnetization.

Power Efficiency

Other types of magnets such as electromagnets necessitate electricity to originate magnetic fields. However, the N40 neodymium rare earth magnets originate robust magnetic fields internally resulting in energy efficiency.

Small Size

The N40 magnet can be manufactured in relatively small sizes and this does not mean that the magnetic forces will be low. This is highly advantageous, especially to applications with a demand for sturdy magnetic forces but with limited space.

Key Features of N40 Neodymium Magnets


Compared to other grades of neodymium magnets as well as other rare earth permanent magnets, N40 neodymium magnets are quite popular. They exhibit distinct characteristics and here is a breakdown of their primary features:

Maximum Energy Product

The maximum energy product is typically abbreviated as BHmax and it measures the power of magnets. The BHmax value of N40 magnets is 40MGOe and this translates into relatively powerful magnetic forces.

Maximum Operating Temperature

The N40 permanent neodymium magnets must operate within certain temperature thresholds for their magnetic capabilities to remain optimal. If subjected to temperatures exceeding 80°C, these magnets may experience demagnetization ranging from mild to permanent.

Curie Temperature

Magnets can become non-magnetic if their curie temperature is exceeded. For N40 NdFeB magnets, this temperature point is capped at 350°C. This underlines the significance of protecting these magnets from extreme temperatures.


Remanence simply quantifies the magnetic powers equipped into a magnet post-magnetization. Neodymium magnets generally have high magnetic induction values and for the N40 grade magnets, this value varies from 12.6-12.9 kilogauss (kG).


N40 neodymium magnets can hold onto their magnetic powers inherently and this translates into a high coercivity value at 11.405 kOe. This distinguishes the N40 magnets as some of the strongest permanent magnets available today.

Types of N40 Neodymium Magnets

N40 Bar Magnet

The N40 bar magnet bears a resemblance to a rectangular rod. These magnets are available in distinct sizes and they produce extremely robust magnetic fields. This makes them ideal for use in magnetic stirring and other industrial processes.

 N40 Bar Magnet
N40 Bar Magnet

N40 Cylinder Magnets

Cylindrical magnets bear a tubular design and they emit uniform magnetic fields. As such, they are often employed in magnetic sensors and magnetic bearings.

N40 Cylinder Magnet
N40 Cylinder Magnet

N40 Disc Magnets

The N40 neodymium magnets are identifiable by their spherical yet flat shape. They have exceptional holding power hence they are primarily used in refrigerator doors and jewelry clasps.

N40 Disc Magnet
N40 Disc Magnet

N40 Ring Magnets

Ring magnets are shaped like a doughnut but with a void in the middle. Their magnetic field is generated around the void hence they are highly employed in audio speakers and magnetic couplings.

N40 Ring Magnets
N40 Ring Magnets

N40 Magnet Balls

These magnet types are round-shaped just like a literal ball. They come in compact sizes and are extremely strong. The N40 neodymium ball magnets are ideal for making toys and other creative projects.

N40 Magnetic Balls
N40 Magnetic Balls

Other N40 Magnet Types Include

  • N40 magnet cubes.
  • N40 block magnets.
  • N40 countersunk magnets.
  • N40 horseshoe magnets.

Comparing N40 Magnets with Other Grades of NdFeB Magnets

NdFeB magnets are typically manufactured in varying grades to sufficiently gratify the distinct demands of unique applications. These grades are based on the magnetic strength and are often indicated by the letter N followed by a number. The number represents the magnetic power. For neodymium magnets, commercially available magnetic grades range from N35 to N55.

The increase in the N number suggests an increase in magnetic strength, coercivity, and remanence. For instance, N40 magnets will exhibit a higher BHmax value (40 MGOe) than N35 magnets at 35 MGOe. However, their magnetic strength will be lower when compared to N55 NdFeB magnets.

Why N40 Neodymium Magnets Need Coating

After N40 neodymium magnets are magnetized during production, they are often subjected to further treatment. This is typically known as surface treatment and it involves covering the magnets in an anti-corrosive coat. The coatings can be made from varying materials, however, the most prominently used substances are nickel, zinc, and epoxy resin. The coating does not only help avert corrosion and oxidation, it is also pivotal in:

  • Improving durability
  • Elevating temperature resistance
  • Minimizing friction
  • Improving handling safety

Common Applications of N40 Magnets

N40 magnets find extensive usage across varying fields thanks to their remarkable magnetic forces and diversity. Here are some of their most common applications:

  • Magnetic toys.
  • Magnetic bearings.
  • Wind turbines.
  • Magnetic door catches.
  • Magnetic sensors.
  • Magnetic levitation.
  • Magnetic holding.
  • Magnetic separation.
  • Magnetic jewelry clasps.
  • Electric motors.
  • Magnetic separators.
  • Magnetic stirrers.

With unparalleled magnetic strength and long lifespans, the N40 neodymium magnets are the way to go for many industries. They have proven to be effective when used to make toys and even when used in industries to achieve magnetic separation. Furthermore, it is projected that they will only get better as newer manufacturing technologies are incorporated.

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