Do I Need to Worry About Temperature With Neodymium Magnets?
Do I Need to Worry About Temperature With Neodymium Magnets?
Neodymium magnets lose some magnetic strength with each degree that the temperature rises, which can be particularly problematic for smaller or thinner magnets.
To avoid demagnetization and permanent reduction in magnetic performance, ensure your neo magnets are stored safely in an environment free from extreme temperatures and dry environments. Avoiding extreme heat also helps protect them against demagnetization that could otherwise permanently diminish their magnetic performance.
Maximum Operating Temperature
Neodymium magnets are among the strongest magnetic materials on the market and can be extremely hazardous if exposed to extreme temperatures. Their atoms move more rapidly when heated, altering their behavior and decreasing strength over time - so it is crucial that users understand their maximum operating temperature for each type of neodymium magnet that they own.
Neodymium magnets can withstand higher temperatures than others, yet still suffer losses of their magnetic field strength due to demagnetization. This process may be reversed or irreversible depending on your application needs.
As such, it is vital that the appropriate grade and materials for your application be chosen. Samarium cobalt (SmCo), AlNiCo (aluminum nickel and cobalt), and high temperature Neodymium rare earth (NdFeB) magnets offer some of the highest temperature tolerances and performance can remain intact up to 450-900degC.
There are various grades of neodymium magnets, each designed for specific temperatures. "M" grades offer maximum operating temperatures up to 80degC while NdFeB and ceramic ferrite magnets may reach temperatures as high as 230degC.
Each neodymium grade has its own maximum operating temperature, which may differ depending on the magnet's shape, application and grade. Furthermore, while they can be cooled down to their Curie temperature of 590degF/310degC for storage purposes, any time above this point they lose their effectiveness permanently.
An essential factor when purchasing neodymium magnets is their level of corrosion protection. Corrosion can severely deteriorate magnet surfaces and even spall them off entirely; to combat this issue, protective coatings like gold plating, nickel plating, zinc plating or epoxy resin coating are available to ensure they're shielded from environmental factors.
As it varies with temperature, Intrinsic Coercivity (Hci) changes with temperature causing demagnetization to take place. With each degree celsius increase in temperature neodymium magnets will lose approximately 0.11% of their magnetic strength; however, once they cool this loss will fully be recovered.
Curie Temperature
Neodymium magnets are renowned for their strength and longevity; however, they're also susceptible to heat. Therefore, it is crucial that we know exactly how much heat these magnets can withstand before their magnetic properties deteriorate completely.
One key indicator of heat resistance in magnets is their Curie temperature. This indicates how hot a magnet can get before its magnetic force permanently dissipates.
As such, if the Curie temperature of a neodymium magnet is exceeded, its functionality as a magnetic device will no longer exist and may even render it inoperable if an attempt to remagnetize is made.
Many manufacturers produce neodymium magnets capable of withstanding high temperatures, and some models may even be designed with dysprosium or erbium to further increase heat resistance.
However, although these materials can increase heat resistance for neodymium magnets, they may reduce overall strength of the product. We advise performing internal tests on your magnet to make sure that it can handle the temperatures you require it for.
Neodymium magnets experience an inexorable loss of magnetism for each degree Celsius that they are exposed to, fully recoverable once cooled off; however, excessive temperatures could pose an ongoing threat to its performance and become detrimental.
To avoid such issues, it is recommended that you utilize neodymium magnets designed specifically for high temperatures - these will typically have labels indicating their temperature rating.
Neodymium magnets with the letter "SH" carry an optimal operating temperature of 150degC or 302degF; those carrying UH have temperatures that can go as high as 180degC/356degF.
Neodymium magnets remain highly popular due to their durability and strong magnetic properties; as a result, they're used in various applications from loudspeakers to power generators.
Knowledge of the Curie Temperature for neodymium magnets is crucial, as it allows you to determine its maximum operating temperature without damaging its magnetic properties and therefore save you from potentially ruinous mistakes with your magnets.
Heat Resistance
No matter their size, shape, or use, all neodymium magnets lose some percentage of their magnetic strength with every degree Celsius of temperature increase. This happens because their constituent atoms become disorganized under heat exposure, leading them to move faster and sporadically than before.
Cold temperatures have the opposite effect; when magnets' temperatures decline, their atoms begin to align again and strengthen them further.
Neodymium magnets are often employed in applications where temperature can have a major impact on their performance, such as high-efficiency motors in residential air conditioning systems. Neodymium magnets have proven themselves capable of withstanding such extreme conditions.
However, there are exceptions. Certain neodymium magnets have been designed to withstand very high temperatures of up to 150deg Celsius without sustaining damage.
How well neodymium magnets withstand higher temperatures is determined by two main factors: usage and treatment from external demagnetizing fields. Neodymium magnets used in brushless DC motors often experience additional forms of demagnetization due to high-speed rotation.
Neodymium magnets used in these applications must be designed specifically to withstand their higher operating temperatures by either altering their structures or having higher Hci ratings to offset any effects from exposure and external demagnetizing fields.
An Hci rating higher than 1 indicates that neodymium magnet's Intrinsic Coercive Force will be less susceptible to demagnetizing fields, and can also feature longer pole cross sections which better resist this form of demagnetization.
While these characteristics are essential to understanding neodymium magnets' heat resistance, it's also important to remember that their magnetic circuit will degrade at some point - known as Curie temperature - which will cause its pull to begin diminishing over time.
Cold Resistance
Neodymium magnets are one of the strongest permanent magnets currently on the market. Used in applications ranging from motors, sensors and holding devices to motor vehicles and discs and blocks - they come in an assortment of shapes and sizes for your convenience.
Neodymium magnets stand out for both their exceptional strength and cold resistance, enabling them to work at extreme temperatures without losing performance.
Magnetic separators and servo motors both rely heavily on temperature stability for operation, while computer disc drives require this property as well.
As a rule of thumb, most types of magnets can operate up to -40degC while certain materials have higher operating temperatures; for example ferrite magnets have lower temperature thresholds than their neodymium counterparts.
Heat above Curie temperature causes magnets to lose their ability to generate strong magnetic fields, known as demagnetization, whether this be temporary or permanent loss.
At the same time, it is vitally important that neodymium magnets be stored in an environment free from water or humidity - ideal storage conditions would include separate compartments rather than stacking.
Additionally, certain neodymium magnets may be susceptible to hydrogen embrittlement due to Hydrogen Decrepitation which causes strip cast material to shatter into tiny flakes.
Once cooled back down, small domains will return to their original states and produce magnetic fields once more. Therefore, even though their magnetism temporarily decreases due to overheating, neodymium magnets may still be useful in many applications despite temporarily losing strength.
Neodymium magnets are often the go-to choice when it comes to magnet applications that require high strength at minimal size and space requirements. Their unparalleled magnetic strength makes them the superior option in applications requiring small spaces and high performance.