When we added Soft Magnetics to our magnetic products portfolio, one of the most common questions we were then asked was 'What are soft magnetics?' Simply, soft magnetic materials are those that can be easily magnetised and demagnetised and their primary use is to enhance and/or channel the flux produced by an electric current.
Soft magnetics have many characteristics that perfectly suit many electrical applications. The low coercivity of soft magnetic materials (typically less than 1000 Am-1) means that it is relatively easy to magnetise and demagnetise the material. Soft magnetic materials are also characterised by high permeability, which is a measure of how easily a material can be magnetised.
The characteristics of soft magnetics lead to their use in a diverse range of applications. The types of applications fall into two categories: AC and DC. In a DC application, the material is magnetised to perform an operation before being demagnetised. Whereas in AC applications, continuously cycling of the material, from being magnetised in one direction to the other, occurs throughout the period of operation, e.g. a power supply transformer.
Permeability is likely to be the main consideration for material selection in DC applications such as in shielding applications where channelling of the flux must be through the material.
For AC applications, the key consideration is the amount of energy lost in the system during the cycling of the material around its related hysteresis loop. A reduction of the intrinsic Coercivity reduces the hysteresis losses.
Soft magnetic materials are essential components of many modern electronic and electrical devices. They play a vital role in the generation, transmission, conversion, and storage of electrical energy. The diverse range of applications for Soft Magnetics includes:
At Bunting, we consider three (3) categories of soft magnetic materials:
Metal cores are made of metal strips which can be wound or stamped to make various, but limited, shapes for relatively low frequency applications up to 50KHz. One exception is EMI suppression applications up to several hundred megahertz.
There are four (4) main types of metal cores:
These cores, composed of compacted insulated iron particles, are mainly used for power chokes due to the resulting distributed gap. Includes standard iron powder and several alloyed versions designed to reduce power losses, audible noise and have improved DC bias properties. Soft Magnetic Composite (SMC) is a new emerging materials using high purity iron particles, replacing electrical steel in some motor applications due to the material's superior high frequency characteristic. Also, SMC has superior flexibility of core shape for more intricate designs;
Soft ferrite cores are classed as ceramics due to synergies in the manufacturing process and the material's hard but brittle nature. There are several subcategories, of which the main ones are MnZn for power and high permeability applications, and NiZn for high frequency applications and those requiring very high resistivity. Other specialist categories include microwave ferrites;
Bunting designs, manufactures and supplies a wide range of soft magnetics, magnets, magnet setters, magnetisers, and magnetic assemblies. Many are bespoke for specific applications. For further information on any of the products mentioned in this article, or for bespoke magnet assemblies and magnet designs, please contact us via:
Phone: +44 (0) 1442 875081
Email: sales.berkhamsted@buntingmagnetics.com
Via Bunting-eMagnets for online purchase of Magnets and Magnetic Technology
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