Measurement of magnetic properties

Complete parameters measurement

The main magnetic characteristics of permanent magnets are called intrinzic (ie internal). This means, that these characteristcics do not show themselves outwardly, such as temperature or weight, but must be measured in a particular system. Changes to this system due to the measured magnet subsequently correspond to its magnetic parameters. In a similar way f.i. electrical resistance is measured. Measurement of magnetic properties, however, requires disproportionately complicated apparatus. To measure the full characterization is used so called hysterezigraph. In principle we talk about electromagnetic circuit with an air gap, into which the measured magnet is inserted. The control computer continuously changes the current by electromagnet coil and also measures the intensity of the magnetic field H and the magnetic induction in the measured magnet B.
From the recorded course of B vs. H the hysteresis curve is obtained, from this curve are subtracted landmarks - coercivity, remanence, and maximum product - see chapter Terms in magnetism.
Hysteresis curve may be measured at different temperatures . You can obtain information on the thermal behavior of the magnet.
For more information see standard IEC 404-5 (1982) magnetic material Part 5: Test measure for hard magnet (permanent magnet) material properties.
 

Measurement of the relative magnitudes

Nevertheless, we can find out relevant data about the quality of the magnet by simpler methods. We talk about measurement of the surface magnetic field and magnetic flux by Webermeter. In the first case, we mostly talk about measurements with Hall probes, in the second case, we mean a measuring coil passed through by magnet itself.
An important condition for the accuracy of such measurements is comparison with the ethanol of the same type and size of the magnet, which has a known background characteristics (measured by hysterezigraph).