Do you know that the performance of your sintered NdFeB magnets can make or break your high tech applications? Learn the latest techniques to get top quality and reliability.
Magnetic Performance Standards
How do manufacturers guarantee every NdFeB magnet meets the performance standards? What are the new methods to measure magnetic properties accurately? In this article we will go into the principles and technologies used to test the magnetic performance of sintered NdFeB magnets to meet the highest standards.
Key Methods
Measuring Surface Magnetic Field with a Tesla Meter
A Tesla meter is required to measure the surface magnetic field of sintered NdFeB magnets. This method mainly uses Hall effect Tesla meters which are very effective in permanent magnet material testing. The Hall effect generates an electric field in a semiconductor when exposed to a magnetic field perpendicular to the current direction. This field is proportional to the magnetic field so precise measurements can be made.
Key points:
Perpendicular Alignment: Make sure the Hall probe plane is perpendicular to the magnetic field direction and stick to the magnet surface.
Uniform Measurement: Since surface fields vary at different positions, measure at a fixed position for consistency.
Measuring Magnetic Flux with a Fluxmeter
Magnetic flux calculated by the electromotive force induced in a measurement coil (Maxwell’s equations) is required for comparative measurements. This method is widely used in permanent magnet testing but variations can occur depending on the sample position within the coil especially for small samples.
Measuring Magnetic Moment with a Helmholtz Coil and Fluxmeter
For high coercivity permanent magnets with small or complex shapes, surface field or flux measurement can be difficult due to scattered readings. For such magnets, measuring the magnetic moment with a Helmholtz coil and fluxmeter is best. This method is fast, accurate and minimizes errors and is good for complex shapes.
Permanent Magnet Density
The density of sintered NdFeB magnets, defined as mass per unit volume, is a key quality indicator. The theoretical density of Nd2Fe14B is 7.62 g/cm³, pure ternary magnets is 7.5-7.55 g/cm³. Adding dysprosium or terbium can increase the density slightly.
To measure the density accurately, use the hydrostatic weighing method which is based on Archimedes’ principle. Weigh the sample in air and in a fluid with known density, such as anhydrous ethanol (0.989 g/cm³) or distilled water (1.003 g/cm³) to calculate the volume and density of the sample.
Conclusion
Ready to optimize the magnetic performance of your NdFeB magnets? Implement these testing techniques today to ensure your products stand out in quality and reliability. For more in-depth information, contact our experts for personalized advice.
