Magnetic properties of materials and components

In quality testing, it is no longer just the mechanical properties of components but also their magnetic properties that play an important role.

The rapid development of electronic drives has brought with it new tasks and challenges in quality testing. It is no longer just the mechanical properties of components that are important, but also the reaction of the material on electromagnetic fields. Components are required to be made of materials that can be easily magnetized so that the electromagnetic system can work quickly and with as little energy consumption. In such cases, magnetic properties in general and magnetic hysteresis are useful criteria for assessing the energetic efficiency of the material in the final application.

Soft Magnetic Components

Definition of some magnetic parameters

Magnetic hysteresis loop represents the relationship between field strength H and polarization J (or flux density B) during magnetization process (or closed field strength cycle) and has a characteristic loop topology. The most important magnetic parameters of the ferromagnetic material can be read from the hysteresis loop. Remarkably, the dimensions of the hysteresis loop give various insights not only into the microstructure of the material, and thus into the mechanical properties, but also into the dynamic behaviour of the material in the magnetic circuit.

Abb 1: Hysteresis Curve

Some important magnetic parameters are listed below:

Magnetic polarization J
The magnetic polarization J is a magnetic flux density induced in the magnetized material or component, which has a direction and a magnitude (vector quantity).

Magnetic field strength H
The magnetic field strength H is an induced magnetic field (e.g. by the magnetizing coil) in a material-free space, which has a direction and a magnitude (vector quantity).

Magnetic flux density B
In the magnetized material, the sum of the polarization J and the magnetic field strength H (multiplied by the physical constant µ0) is represented by the magnetic flux density B, which has a direction and a magnitude (vector quantity).

Saturation polarization J_s
Saturation polarization J_s is the highest achievable magnetic polarisation in a magnetic material (at a given temperature) in the magnetization process.

Coercive field strength H_cJ
The coercive field strength H_cJ is the magnetic field strength of the point on the magnetic J(H) hysteresis for which the magnetic polarization J is zero.

Remanence J_r
The remanence J_r is the magnetic polarization of the material on the J(H) hysteresis for which the magnetic field strength H is zero.

Initial curve
The initial curve is the part of the J(H) hysteresis starting from the magnetically neutral or demagnetized material state (H = 0 and J = 0).

Permeability
The magnetic permeability µ is the ratio of magnetic flux density B to magnetic field strength H in a homogeneous and isotropic material. The relative permeability µr is the ratio of µ to the physical constant µ0, and is a measure of the permeability of matter to magnetic fields.

KOERZIMAT 1.097 HCJ/J-H

The KOERZIMAT 1.097 HCJ measuring system by FOERSTER facilitates the accurate, automatic, and fast measurement of the coercivity H_cJ. The largely geometry-free measurement is particularly suitable for testing samples with complex shapes. The extension module J(H) measurement offers the possibility to determine the complete J(H) Hysteresis on soft magnetic steel incl. the initial curve for round bars and metal sheets.

KOERZIMAT 1.097 MS

The KOERZIMAT 1.097 MS measuring system by FOERSTER facilitates the accurate, automatic, and fast measurement of the weight-specific saturation polarization σ_s and volume-specific saturation polarization J_s. The largely geometry-free measurement is particularly suitable for testing samples with complex shapes.

For further information please visit: https://www.fluxgate-magnetometer.com/products/koerzimat-1.097/