How do the magnetic properties of N35H disc magnets for speakers change at different temperatures?

N35H disc magnets are a high-performance permanent magnetic material that is widely used in scenarios that require strong magnetic fields, such as speakers, headphones, and audio equipment. The performance of its magnetic properties at different temperatures is one of the key factors in product design and application.

The magnetic energy product (B-H) of N35H disc magnets reaches the N35H level, which means that it has a high output capacity in terms of magnetic field strength and flux density. This type of magnet is usually made of high-performance neodymium iron boron (NdFeB) material and is surface treated (such as nickel plating, cobalt plating, etc.) to improve its corrosion resistance and temperature stability. Its main advantages include:

High magnetic energy product: can provide strong magnetic field output;

High coercivity: can still maintain strong magnetism after the external magnetic field is removed;

Good temperature stability: maintain stable magnetic properties within a certain temperature range;

High chemical stability: not easy to corrode in a variety of chemical environments.

Mechanism of Change of Magnetic Properties of N35H Disc Magnets with Temperature
When the temperature rises, the magnetic properties of N35H magnets will be affected by the following aspects:

1. Change of hysteresis loop
Temperature increase: As the temperature rises, the hysteresis loop of the magnet will become steeper, indicating that its magnetic permeability decreases.
Decrease in magnetic flux density: At high temperatures, the magnetic flux density (Bz) of the magnet will decrease significantly, resulting in a weakening of the magnetic field strength.
Decrease in coercive force: Coercive force (Hc) is a measure of the ability of a magnet to maintain its magnetism after the external magnetic field is removed. As the temperature rises, the coercive force will gradually decrease, and the magnet will be more easily demagnetized.

2. Change of magnetic energy product (Bm×Hm)
The magnetic energy product (Bm×Hm) is an important parameter for measuring the magnetic properties of a magnet, indicating the magnetic energy output when the maximum magnetic flux density (Bm) and maximum magnetization (Hm) are reached inside the magnet.
Temperature increase: As the temperature rises, the magnetic energy product will gradually decrease, especially in the temperature range of more than 80-120°C, the magnetic energy product will decrease significantly.
Optimal operating temperature range: The optimal operating temperature of N35H magnets is usually between 20°C and 80°C. Beyond this range, the magnetic properties will decrease significantly, affecting the sound quality and efficiency of the speaker.

3. Changes in magnetic declination and flux direction
Magnetic declination: N35H magnets have a small magnetic declination and a relatively stable magnetic flux direction, which is suitable for forming a uniform magnetic field in speakers.
Temperature change: Although temperature changes have little effect on magnetic declination, at extremely high temperatures, the magnetic flux direction of the magnet may shift slightly, resulting in uneven magnetic field distribution and affecting the sound quality of the speaker.

4. Changes in the physical structure of the magnet
Thermal expansion: As the temperature rises, the magnet material will undergo thermal expansion, which may cause the magnet size to change, thereby affecting the distribution and strength of the magnetic field.
Material performance degradation: At high temperatures, the coating on the surface of the magnet may fall off or discolor, affecting its corrosion resistance and appearance quality.

Typical magnetic performance data of N35H disc magnets at different temperatures (example)

Note: The above data is an example, and the actual values ​​may vary slightly due to magnet batches, manufacturing processes and test conditions.

Temperature range and recommendations for N35H disc magnets

Recommended operating temperature range: 20°C to 80°C
Limit operating temperature: 120°C (short-term use)
Long-term use recommendations: Use below 80°C to ensure stable magnetic properties and avoid magnetic degradation and performance degradation.

Precautions for the application of N35H disc magnets in speakers

Heat dissipation design: Design a good heat dissipation system inside the speaker to reduce the operating temperature and extend the life of the magnet.

Magnet size optimization: According to the power and frequency response requirements of the speaker, reasonably select the magnet size to make it work within the optimal temperature range.
Material selection: In high temperature environments, it is recommended to select magnet materials with higher temperature stability, such as N42H or higher grade magnets.
Environmental control: When used in high temperature or high humidity environments, protective measures should be taken, such as sealing the housing or using high temperature resistant coatings.