Arc magnets are widely used in motors, sensors, medical devices and new energy fields due to their unique geometry and strong magnetic properties. Accurately measuring their magnetic field strength is not only the key to ensuring product quality but also a necessary step to optimizing application performance. This article details the simplified steps, core parameters, applicable tools and practical application scenarios for measuring the magnetic field strength of arc magnets to help engineers and companies efficiently evaluate magnet performance.

Equipment and environment settings

Accurately measuring magnetic field strength requires the use of high-precision instruments such as gauss meters, flux meters or Hall effect sensors to ensure that the instrument range covers the expected magnetic field range of the magnet. It is recommended to use a calibrated digital Gauss meter with an accuracy of ±0.5%. Prepare a workbench without magnetic interference. It is recommended to use a fixing fixture made of non-ferromagnetic materials to ensure that the arc magnet is stable and the magnetic field direction is clear. The experimental environment should be away from electromagnetic equipment, ferromagnetic objects and power cords to avoid external magnetic field interference.

Data collection

On the workbench, you should secure the arc magnet and ensure that its arc surface is directed to the measuring probe so that it does not slide or tilt. Switch on the magnetic field meter, warm up for 5-10 minutes so that the performance is stable, and pick the correct range as per the magnet specifications. Slowly approach the probe to the magnet surface, keep a distance of 0.5-1 mm, and record the magnetic field strength value.

To obtain a comprehensive magnetic field distribution, multi-point measurements are performed along the arc surface, edge and centre point of the magnet. It is recommended to record data every 5 mm to cover the entire magnet surface. In addition, measure the magnetic field strength at different distances to analyze the attenuation characteristics.

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Import the collected data into the analysis software, organize it into a table, and record the magnetic field strength values at each position. Use the drawing tool to draw a curve of the relationship between magnetic field strength and distance to analyze the uniformity and attenuation law of the magnetic field distribution. Calculate key indicators, including average magnetic field strength, maximum value, minimum value and standard deviation, to evaluate the stability of magnet performance.

Core parameters of magnet strength

Magnetic field strength (H, unit: ampere/meter, A/m, or oersted, Oe) reflects the size of the magnetic field generated by the magnet in space and is the basic indicator for evaluating magnet performance.

Magnetic flux density (B, unit: Tesla, T, or Gauss, G, 1T=10000G) measures the magnetic flux passing through a unit area and directly affects the effectiveness of the magnet in a motor or sensor. 

Coercive force (Hc, unit: A/m) measures the ability of a magnet to resist external demagnetization and is a key indicator for evaluating the long-term stability of a magnet. NdFeB magnets with high coercive force (such as N52 grade) perform better in high temperature or strong magnetic field environments.

Magnetic moment (m, unit: A·m² or J/T) indicates the overall magnetic field strength and direction of the magnet, which can be accurately measured by a vibrating sample magnetometer (VSM), suitable for material analysis in the R&D stage. Pull force (unit: Newton, N, or pound, lb) reflects the attraction of the magnet to the ferromagnetic material and is often measured by a pull-off tester.

Measurement Tools and Methods

Gauss meters are definitely the best choice for complicated curved magnets, and they can even find the magnetic flux density more accurately. A few devices also have the ability to measure three axes, which enables them to get the magnetic field direction data. 

Flux meters are great for measuring the characteristics of coiled magnets by determining the magnetic flux through a certain surface and are even more accurate than Gauss meters. VSMs, i.e., vibrating sample magnetometers, are very precise devices used in laboratories. They give you an opportunity to investigate magnetic moments, hysteresis loops, and coercive forces.

Magnetic force microscopes (MFMs) provide nanoscale magnetic field distribution imaging, suitable for studying defects or magnetic domain structures of micro magnets. Hall effect sensors measure magnetic field strength over a large area through voltage changes caused by magnetic fields, suitable for rapid detection on production lines.

Arc magnet suppliers

In order to identify a reliable supplier of permanent magnets, it is advisable to look for the product quality, ability to customize, stability in supply and experience in the application of the industry. 

Below, we have listed some of the most reliable arc magnet suppliers in the world for you to consider:

Hitachi Metals (Proterial): famous for Neomax rare earth magnets and ferrite magnets, widely used in the automotive, electronics and home appliance industries, focusing on technological innovation and energy efficiency. 

Arnold Magnetic Technologies: Provides high-performance NdFeB, SmCo magnets and magnetic components, serving the aerospace, automotive and motor fields, and excels in customized solutions.

Topmag Technology: The world's leading rare earth magnet manufacturer, its products are widely used in electronics, automobiles and renewable energy fields.

Stanford Magnets: Provides customized NdFeB, SmCo and ceramic magnets, focusing on R&D and diversified applications, serving global customers. [NG-FA]