What Is a Permanent Magnet Component?

What Is a Permanent Magnet Component?

Permanent Magnet Components are magnetic materials which generate and retain magnetic fields. Permanent Magnet Components are widely used in various applications including electromagnets, solenoid valves, electric motors and electromagnetic clutches and magnetic couplings that transmit torque from prime mover to follower without mechanical contact. Common permanent magnet materials include Neodymium Iron Boron (NdFeB), with alnico and Samarium Cobalt 5 also commonly utilized - due to containing rare earth elements these magnets are classified as critical materials requiring strict manufacturing processes that ensure high consistency and reliability over time.

Magnets are composed of ferromagnetic materials with different crystal structures that enable them to have specific magnetic properties such as energy density, remanence and resistance to demagnetization. These properties can typically be measured using AC impedance spectroscopy techniques.

Based on their composition and sintering temperature, permanent magnets can either be anisotropic or isotropic depending on their magnetic field characteristics. Anisotropic magnets feature an alternating magnetic field; for comparison, isotropic magnets have magnetic fields which are always perpendicular to direction; the isotropic magnetic fields of isotropic permanent magnets can be described by the polar equation (Ha)(H). To calculate remanence for such permanent magnets use (Ha+H).

Most magnets are manufactured to exact dimensions and tolerances. They come in all sorts of shapes such as standard rings, bars and discs as well as more complex trapezoid, arc and mitre shapes. Furthermore, permanent magnets can even be custom designed to meet specific application requirements.

Physical and chemical characteristics of magnets make them susceptible to contamination during alloy preparation, powder metallurgy, and sintering processes. Contamination may compromise their magnetic properties or even impede performance if left uncontrolled; hence the necessity of effective contamination suppression throughout production stages.

Permanent magnets undergo magnetization by subjecting them to large fields that allow for saturation of their magnetic fields. Saturations is defined as the point on the demagnetization curve where magnetization equals maximum magnetic flux density of material (BHmax), such as is found for NdFeB, SmCo5, and alnico PMs in Figure 19. Typical saturations for these PM types can be seen here as well.

Once a permanent magnet saturates it cannot be demagnetized; however, it can still be remagnetized. Remagnetizing requires applying a peak field at 2(H) away from its opposing surface in relation to BHmax; furthermore, this peak field must exceed its intrinsic coercivity of the magnet itself.

Most permanent magnets (PMs) are vulnerable to corrosion and should be stored safely away from water, oil and other chemicals that could expose them to moisture or chemical contaminants. Exposure can cause corrosion damage that erodes its magnetic properties and decreases inductance in magnetic circuits; proper handling and storage techniques can help minimize corrosion damage to PMs. Some magnet manufacturers even produce corrosion-resistant coatings designed to safeguard material integrity - these coatings may be applied prior or post use of the magnet for maximum protection from further deterioration.


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