How to Judge Whether a Magnet Has Demagnetized?

How to Judge Whether a Magnet Has Demagnetized?

There are two ways to judge whether a magnet has demagnetized: simple detection and professional instrument testing, which are suitable for different scenarios:

1. Simple Detection Method (On-site Quick Judgment)

◦ Adsorption Force Comparison: Use the magnet to adsorb standard-weight iron parts (such as nuts, iron sheets), and compare it with the adsorption state of a new product. If the adsorption force is significantly reduced, the magnet cannot pick up the parts or falls off easily, it is mostly demagnetized.

◦ Magnetic Pole Test: Approach the magnet to be tested with a known good magnet with clear magnetic poles. If the repulsion/attraction reaction becomes weak or there is no obvious magnetic pole reaction, it indicates that the magnetic performance has attenuated.

◦ Same-batch Comparison: Place the magnet to be tested and a new product from the same batch side by side to adsorb iron products, and observe the difference in adsorption strength. A significant difference means demagnetization has occurred.

2. Professional Instrument Testing Method (Accurate Quantification)

◦ Use a fluxmeter or gaussmeter to measure the surface magnetic induction intensity of the magnet, and compare it with the factory parameters. If the value drops by more than 10%-15% (depending on the material and requirements), demagnetization can be determined.

◦ Detect core performance parameters such as residual magnetism (Br) and coercivity (Hc) through a hysteresis loop tester. If the parameters are lower than the standard values, the magnet is demagnetized.