Sintered neodymium-iron-boron (NdFeB) magnets are widely used in modern technology and industry, such as electric vehicles, wind turbines, and consumer electronics, due to their excellent magnetic properties. To ensure their reliability and performance in various applications, comprehensive testing is necessary. Newland Magnet has a series of professional magnet testing equipments, which can carry out comprehensive quality testing of NdFeB magnets to meet the production quality requirements of NdFeB magnets.
Factors affecting the quality and performance of neodymium magnets:
The magnetic properties of magnets are affected by a variety of intrinsic as well as extrinsic factors, the following are common influences:
Raw material ratios: The magnetic properties of magnets may be affected by the ratio of neodymium, iron and boron in the magnet and the presence of any additional additives or impurities.
Manufacturing Process: Manufacturing processes such as sintering, melting or bonding may also affect the properties and structural integrity of the magnet.
Coatings and Plating: The type and quality of the protective coating used on the magnet may affect its corrosion resistance, appearance and overall durability.
Magnetization: The performance and suitability of a magnet for various applications may be affected by the direction and strength of the magnetic field within it.
Usage Environment: The performance and life of a magnet may be affected by the environment in which it is used, such as temperature, humidity and mechanical stress.
There are various factors that affect magnetic properties. Therefore, after a magnetic product has been processed, a series of tests are required to ensure that the performance of the batch meets the standard requirements.
1. Appearance size and physical properties testing
As the strongest permanent magnet material today, neodymium-iron-boron (NdFeB) magnets must undergo comprehensive appearance dimension and physical property testing in order to ensure their reliability and performance in various applications. The following are common testing items for NdFeB magnets:
| Testing Items | Testing Instrument | Testing Index and Principle | Purpose of Testing |
| Size Inspection | Calipers/Micrometers/Projectors | Test the length, width and height dimensions of the products, as well as key dimensions such as perpendicularity, parallelism, R angle, C angle, etc., to ensure that they meet the requirements of the design drawings. | Check whether the dimensional tolerance is within the specified range to ensure the consistency and interchangeability of the products. |
| Appearance Inspection | Visual Inspection / Coating Inspection | Observe whether there are defects such as pinholes, dropped corners, scratches, hidden cracks, etc. on the surface of the product; check the integrity of the coating. | Prevent products from falling off or being damaged during use due to incomplete plating. |
| Mechanical Strength Testing | Mechanical tester | Test the tensile and compressive resistance of magnets, etc. | Reduce the risk of cracking during product use. |
| Density Testing | Solid density meter | Determine the density of magnets using Archimedes’ principle. | Evaluate the internal quality of the magnet and the homogeneity of the material. |
2. Magnetic property test
Magnetic property is an important index of NdFeB magnets, only the products that strictly meet the requirements of magnetic property can give full play to its efficacy and stable application in the field we need.
Magnetic property test is the core index to evaluate the quality of magnets, mainly including the following aspects:
| Testing Items | Testing Instrument | Testing Index and Principle | Purpose of Testing |
| Residual magnetism (Br) | Gaussmeter | The flux density remaining when an external magnetic field is removed after the magnet has been magnetized to saturation. | Measurement of the magnetic field strength at the surface of a magnet. |
| Coercivity (Hc) | Coercimeter | The ability to resist magnetization or demagnetization even when the magnet is demagnetized to zero with the required reverse magnetic field strength. | Measure the coercivity of a magnet to assess its resistance to demagnetization. |
| Endowed coercivity (Hci) | B-H Curve Tracer | The endowed resistance to demagnetization when the magnet is completely demagnetized. | Measure the endowed coercivity by plotting the hysteresis return line of the magnet. |
| Maximum magnetic energy product (BHmax) | B-H Curve Tracer | The maximum energy density that a magnet can store in a magnetized state. | Evaluate the magnetic energy storage capacity of the magnet and visualize the magnetic performance parameters of the magnet through B-H return line diagram. |
| Surface magnetism | Table Magnetic Distribution Tester/ Tesla Meter | The size of the central surface magnetization or the surface magnetization of a specific area, uniformity of distribution, etc. | Examine the magnitude of the magnetic field in the localized area of the product. |
| Magnetic moment | Magnetic Moment Tester/ Fluxmeter | Magnetic moment value. | Respond more accurately to the magnitude of the product’s magnetic energy. |
3. Microstructure testing and chemical composition analysis
The microstructure testing and chemical composition analysis of NdFeB is mainly to check whether the performance of the product meets the expectation during the production process and to verify whether there are any defects in the production process.
| Testing Items | Testing Instrument | Testing Index and Principle | Purpose of Testing |
| Carbon and Sulfur Content | Infrared carbon and sulfur analyzer | Burning carbon and sulfur in the sample at high temperature to generate oxides. | Detect the content of impurity elements and test the raw material preparation process. |
| Oxygen, Nitrogen and Hydrogen Content | Tester | The sample is converted to CO, CO2, N2, H2 at high temperature for detection. | Analyze the presence and distribution of oxides and non-metallic inclusions in NdFeB magnets. |
| Compositional Analysis | Plasma Emission Spectrometer | Atoms ionize and then jump, detecting the electromagnetic wave energy released, corresponding to the elements of different characteristic spectra. | Analyze the composition of raw materials. |
| Microscopic Inspection | Scanning Electron Microscope/ Energy Spectrometer | Analyze the surface characteristics of the sample by secondary electrons, backscattered electrons and characteristic S-ray signals. | Detect the precision of products. |
4. Environmental Stability Test
Environmental stability test evaluates the performance of magnetic materials in different environments:
Corrosion Resistance Test: assesses the stability of magnetic materials in harsh environments through methods such as salt spray test and damp heat test.
Thermal Stability Test: Detects changes in magnetic properties of magnetic materials in high temperature environments to ensure their reliability in high temperature applications.
Through these comprehensive testing programs, the performance and quality of sintered NdFeB magnets can be fully assessed to ensure their reliability and effectiveness in various applications. With rich experience and expertise in magnetic materials and magnetic circuit design, Newland Magnet is committed to providing customers with high-quality magnetic solutions for a wide range of complex applications.
The performance and quality testing of sintered NdFeB magnets is a key aspect to ensure their excellent performance in practical applications. Through systematic testing and analysis, we are able to detect and eliminate defects in the production process, improving the service life and performance stability of the magnets. Newland Magnet will continue to dedicate itself to innovation and R&D to provide customers with the most advanced magnetic solutions.
![](https://www.newlandmag.com/wp-content/uploads/2024/03/高清原图logo.png"")