Neodymium magnets, also known as Neodymium-Iron-Boron (NdFeB) magnets, are the strongest type of permanent magnets commercially available. They are widely used in various applications, including Renewable Energy to Medical Imaging, Wind Industry, Oil & Gas Industry, Automotive Industry and Daily Use Applications. The performance of neodymium magnets is characterized by their grade, which provides information about their strength, temperature resistance, and other key properties.
Understanding Neodymium Magnet Grades
One crucial aspect that distinguishes neodymium magnets is the most commonly used classification system, denoted by the “N-rating.” We delve into the classifications of neodymium magnet grades, shedding light on the differences and applications of N52, N42, and N35 magnets.
Understanding the N-Rating
The “N-rating” of neodymium magnets represents their grade or strength and is followed by a number, such as N52, N42, or N35, which indicates the maximum energy product (BHmax) of the magnet material in mega-Gauss-oersteds (MGOe). This rating reflects the amount of magnetic energy the material can hold, with higher numbers denoting stronger magnets. For example, an N52 magnet has a maximum energy product of approximately 52 MGOe, while an N35 magnet has a maximum energy product of approximately 35 MGOe.
Simply put
The higher the number, the stronger the magnetism.
The smaller the number, the lower the grade.
Below is a chart of common neodymium magnet grades and their characteristics for reference:
| Grade | Br (KG) | Hcb (KOe) | Hci (KOe) | BHmax (MG Oe) | Tmax |
| N35 | 11.7-12.2 | ≥10.9 | ≥12.0 | 33-36 | 80℃/176F |
| N38 | 12.2-12.5 | ≥10.9 | ≥12.0 | 36-39 | 80℃/176F |
| N40 | 12.5-12.8 | ≥11.4 | ≥12.0 | 38-41 | 80℃/176F |
| N42 | 12.8-13.2 | ≥11.5 | ≥12.0 | 40-43 | 80℃/176F |
| N45 | 13.2-13.8 | ≥11.6 | ≥12.0 | 43-46 | 80℃/176F |
| N48 | 13.8-14.2 | ≥11.6 | ≥12.0 | 46-49 | 80℃/176F |
| N50 | 14.0-14.5 | ≥10.0 | ≥11.0 | 48-51 | 70℃/158F |
| N52 | 14.3-14.8 | ≥10.0 | ≥11.0 | 50-53 | 70℃/158F |
The “N-rating” of neodymium magnets also refers to the maximum working temperature of the magnet with letter suffix, such as N35M, N35H, N35SH, N35UH, N35EH, N35AH. If no suffix like N35, then it means maximum working temperature 80℃.
Neodymium magnet grades (e.g., N42, N52, N35SH) tell you two key things:
1. Strength (Number)
- The number (e.g., 35, 42, 52) shows how strong the magnet is. It’s measured in MGOe (MegaGauss-Oersted).
- Higher numbers = stronger magnets.
- Examples:
- N35: 35 MGOe (Weaker)
- N52: 52 MGOe (Strongest standard grade commercially available)
2. Heat Resistance (Letter)
- The letter (e.g., N, H, SH) shows how well the magnet works at high temperatures:
- N: Normal, up to ~80°C.
- M: Medium heat, up to ~100°C.
- H: High heat, up to ~120°C.
- SH: Super high heat, up to ~150°C.
- UH: Ultra high heat, up to ~180°C.
- EH: Extra high heat, up to ~200°C.
- AH: Advanced high heat, up to ~250°C.
| Letters | N | M | H | SH | UH | EH | AH |
| Max working temperature | 80℃ | 100℃ | 120℃ | 150℃ | 180℃ | 200℃ | 250℃ |
| Grade | Normal | Medium | High | Super High | Ultra High | Extremely High | Atmost High |
| Hcj | 12 KOe | 14 KOe | 17 KOe | 20 KOe | 25 KOe | 30 KOe | 35 KOe |
In short:
- Bigger number = stronger magnet.
- Later letters = better heat resistance.
Common Neodymium Magnet Grades and Their Properties
There are 4 main indicators for measuring the performance of permanent magnets:
1)Remanence (Br):
Remanence, often denoted as Br, refers to the residual magnetic flux density retained by a magnet when the external magnetic field is removed. It indicates the magnet’s ability to maintain magnetization.
2)Coercivity (Hcb):
Coercivity, represented as bHc, is the measure of the resistance of a magnetic material to becoming demagnetized by an external magnetic field. Specifically, it is the reverse magnetic field strength needed to reduce the magnet’s magnetic flux density to 0 after being magnetized.
3)Intrinsic Coercivity (Hcj):
Intrinsic coercivity, sometimes abbreviated as iHc, is similar to coercivity but specifically refers to the resistance of a magnet to demagnetization within its intrinsic structure, without the influence of external factors. The intrinsic coercivity is closely related to the temperature resistance of rare earth permanent magnets, higher intrinsic coercivity higher working temperature.
4)Maximum Magnetic Energy Product (BHmax):
The maximum magnetic energy product, often denoted as (BH)max, is the product of remanence (Br) and coercivity (bHc). It quantifies the maximum amount of magnetic energy that a magnet can store per unit volume, indicating its overall magnetic strength and performance potential.
Different Magnet Grades, Strengths, and Temperatures
Magnets come in different grades, each with varying strengths and temperature resistance. Here’s an easy breakdown:
1. N52 Magnets
- Strength: These are the strongest magnets you can buy, with a maximum energy product of 52 MGOe.
- Uses: Perfect for high-performance applications like motors, generators, and magnetic couplings, where strength is the most important factor.
2. N42 Magnets
- Strength: Slightly less powerful than N52 magnets, with a maximum energy product of 42 MGOe.
- Uses: Commonly used in electronics, healthcare devices, and the automotive industry because they provide strong performance at a slightly lower cost.
3. N35 Magnets
- Strength: Not as strong as N52 or N42 magnets, but still effective with a maximum energy product of 35 MGOe.
- Uses: Ideal for consumer electronics, magnetic therapy products, and magnetic closures, offering a good balance between strength and affordability.
Important to Know:
High Strength vs. High Temperature Resistance:
A magnet can be considered high-grade for its strength (like N52) or its temperature resistance (like N35EH, which works up to 200°C).
Example: N52 magnets are strong, but they cannot handle high temperatures like N35EH.
| Grade | Maximum Energy Product (MGOe) | Maximum Operating Temperature (°C) | Applications |
|---|---|---|---|
| N35 | 35 | 80 | General-purpose applications, toys. |
| N42 | 42 | 80 | Consumer electronics, motors. |
| N48 | 48 | 80 | High-performance devices. |
| N52 | 52 | 80 | Premium-grade magnets, sensors. |
| N42SH | 42 | 150 | High-temperature applications. |
| N45UH | 45 | 180 | Automotive, wind turbines. |
| N40EH | 40 | 200 | Specialized industrial applications. |
In short, choosing the right magnet depends on whether you prioritize strength, temperature resistance, or cost-effectiveness for your application.
Factors to Consider When Choosing Neodymium Magnet Grades
1. Strength Requirement:
Higher grades (e.g., N52) offer stronger magnetic force but are more expensive.
2. Operating Environment:
Consider the temperature at which the magnet will operate. For high-heat environments, use grades like SH, UH, or EH.
3. Corrosion Resistance:
Neodymium magnets are prone to corrosion. Coatings (nickel, epoxy, gold) are often applied, but grades resistant to higher temperatures typically have better stability.
4. Cost:
Higher grades are generally more expensive. Optimize the grade to meet both performance and budgetary needs.
Current Limitations:
Technology doesn’t yet allow for magnets that combine both the highest strength and highest temperature resistance. For instance, there is no grade like “N52EH.”
For more in-depth information on neodymium magnet grades and their applications, please visit our website www.wzmagnetics.com.
