How to Measure the Magnetic Force of Magnet?

    Neodymium magnets are widely used in industrial equipment, electronic devices, motors, sensors, and daily products. When selecting a magnet, many customers focus on one important question: How strong is the magnet? However, measuring magnetic strength is not as simple as judging how strongly a magnet attracts metal objects. Professional measurement requires specific testing methods and considers multiple factors, including material grade, size, shape, magnetization direction, and working environment.

Understanding how to measure magnetic force helps customers choose the right sintered NdFeB magnet and ensures consistent product quality.

1. Pull Force Test: Measuring Magnetic Attraction Force

The most intuitive and widely adopted method to quantify a permanent magnet’s magnetic strength is the pull force test, which is also the primary reference index customers use to judge magnet performance in actual application scenarios.

This standardized test calculates the maximum pulling force needed to detach the tested magnet from a flat, thick, high-purity standard carbon steel plate under strictly ideal laboratory conditions, eliminating interference from uneven contact surfaces, gaps, rust or material impurities.

In the complete testing procedure, the strong neodymium magnet is fully attached flat against the smooth steel substrate with zero air gaps between two contact faces. A vertically upward, steady tensile force is slowly and evenly exerted on the magnet via professional tension testing equipment. The instrument continuously captures real-time tension data until the magnet completely breaks away from the steel plate. The peak tension value captured at the moment of separation is defined as the rated pull force of the magnet. This value is conventionally marked in three common units for global trade: kilograms (kg), Newtons (N) and pounds (lb).

2. Measuring Surface Magnetic Field with a Gauss Meter

A gauss meter is a professional measuring instrument specially designed to test magnet surface magnetic performance. It works by touching its tiny precision probe directly onto designated positions of the magnet to detect the local magnetic flux density at those exact testing points.

It is important to note that magnetic field distribution on a single magnet is never uniform. Even one intact finished magnet carries varying magnetic strength across different surface zones. Take a round disc neodymium magnet as a typical example: the magnetic field at the geometric center is significantly stronger, while the magnetic flux density gradually weakens toward the outer peripheral edges. This uneven magnetic distribution is a normal physical characteristic of permanent magnets.

Gauss value testing is a core quality control procedure widely implemented throughout magnet mass production. For our factory, we rely on this inspection method to double-check two key criteria: first, whether each magnet has reached the full, required magnetization level without under-magnetization or incomplete magnetizing issues; second, to monitor performance stability across bulk production batches.

3. Evaluating Magnet Performance Through Magnetic Parameters

For high performance magnets such as neodymium magnets, magnetic force is also evaluated through professional magnetic parameters:

• Br (Remanence): Indicates the magnetic field strength remaining in the magnet after magnetization. A higher Br generally means stronger magnetic output.

• Hcb (Coercive Force): Shows the magnet’s ability to resist external demagnetizing forces.

• Hcj (Intrinsic Coercivity): Measures the magnet’s resistance to internal demagnetization, especially under high-temperature conditions.

• BHmax (Maximum Energy Product): Represents the maximum amount of magnetic energy stored in the magnet and is an important indicator of overall magnetic performance.

Generally, higher grades provide stronger magnetic performance in the same size magnet.