Neodymium is the strongest available magnet alloy at up to 52MGOe. The use of Neodymium results in smaller, more cost-effective magnet solutions replacing older materials like Alnico and Ceramic in many applications. Magnosphere.co.uk can help optimize performance and cost with Neo magnets in grades from 33 to 52MGOe and operating temperatures up to 230°C/446°F. Stock Neodymium magnets also available.
Many grades of Neodymium exist to support a variety of industrial and commercial applications. The range of Neo grades is typically 33 to 52 MGOe. These ranges allow for balancing cost, magnetic performance, and operational temperature resistance.
Many grades of Neodymium magnets exist to support a variety of industrial applications. The range of Neo grades typically extends from 33 MGOe to 52 MGOe. This range allows for optimizing cost, performance, and operational temperature resistance.
The typical convention for “Grade” is to use the value of the particular magnet alloy’s Energy Density or Maximum Energy Product. Oftentimes there are letters or a two digit number suffix attached to the Grade which indicates the Intrinsic Coercive Force (Hci) level of the magnet alloy. This Hci is a good indicator of the maximum allowable temperature a particular Neo alloy can tolerate before irreversible demagnetizing occurs.
The higher the “Grade number” then the higher the Energy Density. Usually the higher the Energy Density the stronger the magnet, but this is very much dependent upon the magnet’s operational environment.
Neodymium magnets have poor resistance to corrosion and they can also corrode from the inside out if proper pre-treatment processes are not followed. Oftentimes a multi-layer Nickel-Copper-Nickel plating is applied, but this may not be sufficient for all applications.
Neodymium magnets have poor resistance to corrosion and they can also corrode from the inside-out if proper pre-treatment processes are not followed. Oftentimes, multi-layer Nickel-Copper-Nickel plating is applied to prevent failure from corrosion, but this preventative technique may not be sufficient for all applications.
*Fully dense Neodymium Iron Boron is made with a powdered metal process. The quality of the powder dramatically impacts the resulting Neo magnet’s magnetic performance as well as environmental tolerance. Appropriately sized, well-formed powder grains which have little un-reacted constituent elements will result in highly performing magnets. Even magnets made with ideal powder will still have some un-reacted components which will oxidize or rust. (Poorly made magnets may oxidize from the inside out.)
Typically a corrosion preventive layer is applied in the form of a coating or plating. Because of the reactive nature of the NdFeB alloy, coating and plating adhesion is always a concern. Neo magnets are not coated or plated to a particular ASTM, ASM, etc. specification; however, the performance of a coating or plating is typically evaluated with a Salt Spray/Salt Fog Test (SST) and this is executed in accordance with ASTM B117.
The Neo alloy, magnet geometry, and corrosion inhibiting layer work in concert to extend the operational life of the magnet. Dura has compiled minimum performance characteristics of various coating and plating options for Neo magnets based on the ASTM B117 Salt Fog testing method. This method is only for evaluating Neo magnets which have a corrosion inhibiting layer.
Neodymium Magnets without coating or plating will fail immediately in the Salt Fog environment. The Salt Fog test is used to evaluate the performance of the plating or coating and it is not used to judge the quality of the Neo alloy itself. Various elevated temperature and humidity test can be used to evaluate the bare Neo alloy. The effective volume loss of the evaluated neo magnet is used to determine the quality of the neo magnet alloy. One compares the effective mass before and after the environmental testing exposure. (The “lost” volume is portion of the Neo alloy which reacted during the environmental testing and “rusted”. The rust/oxidation is removed from the sample and the resulting mass difference between the initial state is quantified.)
It is imperative to apply the correct corrosion inhibiting layer or to encapsulate any Neo magnet used in a commercial application. (The corrosion preventative layer can be absent for proof of concepts and prototypes.)
Please engage a Magnosphere application specialist for help with determining the best method for extending the operational life of the Neodymium magnet to be used in your application.
Neodymium magnets are very susceptible to elevated operating temperatures and the application requirements should be considered before selecting a particular grade of Neo.
Neodymium Magnets are very susceptible to losing their effective magnetic field at elevated temperatures. The Neo magnet grade should be carefully selected to account for the operational temperature of the application and the magnet’s geometry. All magnet alloy will gain or lose effective magnetic field as the temperature flucuates. Neo magnets will lose effective field as the temperature increases and are said to have a Negative Temperature Coefficient. When compared to other magnet alloy options, neo magnets lose magnetic field at a faster rate. Neo magnets effectively have a higher Temperature Coefficient (TC) when compared to other commercial alloys.
This high rate of change relative to temperature exposure results in Neo magnets being very susceptible to demagnetizing from elevated operating environments. The magnet may be exposed to a temperature which does not fully demagnetize, but reduces its’ magnetic performance to a state that it no longer is able to provide sufficient magnet field to support the application.
The loss that has been discussed thus far is considered reversible. This means that the magnet will recover the loss as it cools back down. What is typically published by suppliers of magnets is the Reversible Temperature Coefficient (RTC) for each particular grade of Neo for both the Residual Induction (Br) and the Intrinsic coercive Force (Hci). The RTC as well as the recommended Maximum Operating Temperature must be considered when selecting a Neo magnet grade for an application above ambient room temperature.
Although most commercial magnets are anistropic, which means they have a preferred direction of magnetization, various pole configurations can be achieved without conflicting with a Neodymium Magnet’s orientation.
Most useful commercial magnets are anisotropic which means that they have an “Easy” or preferred direction of magnetization and that an orientation field was applied during the compaction stage of the manufacturing process.
It is essentially impossible to magnetize the resulting anisotropic magnet alloy other than in the Direction of Orientation; however, various pole configurations can be achieved without conflicting with the magnet material’s orientation.
The Neodymium Iron Boron magnets that Magnosphere provides are compliant with Intellectual Property Rights, Environmental Restrictions, and Conflict Mineral usage.
Intellectual property rights exist for commercially viable Neodymium magnet alloys. Many infringing manufacturers from the Pacific Rim can offer cheap pricing because they pay no royalties to the patent holders, utilize substandard raw materials, and have poor Neodymium iron boron (also known as rare earth) magnet manufacturing methods. Utilization of infringing Neodymium magnets may lead to legal issues, delays, and product failures. Dura Magnetics, Inc. only provides licensed Neodymium magnet alloys which are traceable to the patent holders. This assertion of compliant Neodymium magnet alloy is supported by on-site inspections and contractual obligations initiated with alloy producers.
Neodymium Magnets are very strong and brittle, requiring appropriate handling and packing to ensure safety and prevent damage.
Neodymium magnets are very strong and brittle and appropriate handling and packing is required. Most receiving departments are not familiar with the strength of neodymium magnets and this can result in injury or broken parts. All personnel that may come in contact with this alloy should be made aware of the dangers of handling these magnets. The brittle nature of the alloy can lead to flying chips if the magnets are allowed to impact each other or a solid surface. Larger magnets can become a pinching hazard if caution is not exercised. We urge all customers to discuss handling techniques pertinent to their magnets with a Magnosphere team member.
The packaging methods of neodymium magnetized alloys are dependent upon the magnet size and the customer requirement.
A majority of our neodymium magnets are shipped ground by UPS, Fed Ex Ground, or LTL carriers. FAA guidelines consider magnetized material as hazardous goods when the field density emanating from the package sides exceed a specified value. Many air carriers will not accept magnetized material for air shipments. Dura Magnetics is able to ship via air, but a packing/handling charge may be applied for larger volumes. These charges are only applied in extreme cases to cover the cost of extra shielding and packaging material, labor, and necessary paperwork.
Neodymium Magnets are typically manufactured by a powdered metallurgical process utilizing rigid steel or rubber molds.
Fully dense Neodymium Magnets (also known as neo magnets, neodymium iron boron, neo, or rare earth magnets) are usually manufactured by a powdered metallurgical process. Micron size Neodymium and iron boron powder is produced in an inert gas atmosphere and then compacted in a rigid steel mold or in a rubber mold. The rubber mold is compacted on all sides by fluid and it is referred to as isostatic pressing. The steel molds will produce shapes similar to the final product, while the rubber mold will only create large blocks (loaves) of Neodymium magnet alloy.
The Neodymium alloy’s magnetic performance in both compacting methods is optimized by applying a magnetic field before or during the pressing operation. This applied field imparts a preferred direction of magnetization, or orientation to the Neodymium magnet alloy. The alignment of particles results in an anisotropic alloy and vastly improves the residual induction (Br) and other magnetic characteristics of the finished rare earth magnet. After pressing, the Neodymium Magnets are sintered and heat treated until they reach their fully dense condition. The die pressed magnets are ground to the final dimensions, but the brick magnets from the rubber mold method are usually squared on large grinders and then sliced to the final geometry. Isostaticly pressed alloy has higher magnetic properties than the die pressed material, but it may lack the uniformity. The choice of manufacturing method to create Neodymium Magnets is usually application driven and is typically not a concern of the customer.
|Coercivity Hc (kA/m)|| |
Max. energy product
Max. working temp.*
|Normal Hcb||Intrinsic Hci|
|N30||1.08 - 1.13||>= 796||>= 1353||223 - 247||80 - 240|
|N33||1.13 - 1.17||>= 812||>= 1353||247 - 271||80 - 240|
|N35||1.17 - 1.22||>= 868||>= 955||263 - 287||80 - 200|
|N38||1.22 - 1.25||>= 899||>= 955||287 - 310||80 - 180|
|N40||1.25 - 1.28||>= 907||>= 955||302 - 326||80 - 180|
|N42||1.28 - 1.32||>= 915||>= 955||318 - 342||80 - 150|
|N45||1.32 - 1.38||>= 923||>= 955||342 - 366||80 - 150|
|N48||1.38 - 1.42||>= 923||>= 955||366 - 390||80 - 120|
|N50||1.40 - 1.45||>= 796||>= 796||382 - 406||60 - 100|
|N52||1.43 - 1.48||>= 796||>= 876||398 - 422||60|
|N54||1.45 - 1.51||>= 939||>= 875||405 - 437||60|
*Maximum working temperature is differentiated by adding an alphabetical code after the code of material grade (e.g. N35EH = 200°C). Increasing the maximum working temperature results in gradual decrease of material grade:
M - Tw <=100°C
H - Tw <=120°C
SH - Tw <=150°C
UH - Tw <=180°C
EH - Tw <=200°C
AH - Tw <=240°C
Neodymium magnets are hard, brittle and sensitive to crack, so machining is problematic because the protective coating is corrupted. Machining can be carried out by grinding with diamond tools, but the coating must be repaired.
NdFeB magnets have excellent resistance to external magnetic fields and in normal conditions keep their magnetic properties during long time.
|Temp. coefficient of Br (%/°C)||Temp. coefficient of Hci (%/°C)||Magnetizing field (kA/m)||Curie temp. (°C)||Density (g/cm3)||Hardness (Hv)|
|- 0.12||- 0.6||2400||310 - 340||7.5||570|
Magnosphere.uk.co offers best priced Neodymium magnets globally to all industries, including Automotive, Aerospace, Military, Advertising, Design House, Electronic and Academic/R&D. Please inquire for custom Neodymium magnets or magnetic assembly.
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