Ferrite magnets, also known as ceramic magnets, ceramic ferrite magnets, ferrobic magnets and hard ferrite magnets. Ceramic ferrite magnets are one of the most widely used permanent magnet materials in the world. Ferrite magnets are the cheapest magnetic material, this makes the material suitable for productions with large volumes. Ferrite magnets are most popular in motor, generator, speaker and marine applications, but are used in almost every industry. Like for example. Automotive, sensors, machinery, aerospace, military, advertising, electrical/electronic, academic, design houses and in research and development.
They have been nicknamed - ceramic due to their excellent electrical insulating ability. Ferrite magnets are perfect in damp, wet environments because they are corrosion free. The iron is already in a stable oxidized form, which means that the iron can no longer oxidize (rust) when in water.
Strontium ferrite magnets (SrO.6Fe2O3) and barium ferrite magnets (BaO.6Fe2O3) are the two types of ceramic ferrite magnets. The strontium ferrite magnets are the most commonly manufactured due to their stronger magnetic properties.
The ferrite magnets (ceramic magnets) have a characteristic "pencil" color (ie a dark gray color). The magnets can be experienced as somewhat powdery. If you hold a ferrite magnet, there is a risk that your hand will become dusty from the powdery surface.
Working temperature (Coericivity, HcJ) and Material grade (Energy content, BHmax)
Ferrite magnets can be used at temperatures up to a maximum of 250°C (in a few situations even up to 300°C, but this depends on the grade and geometry of the magnet). As with the other magnetic materials, there are also different grades (qualities) of ferrite. Our best selling grades are Y30H-1 and Y30H-2 (we previously spec'd these as FXD380 and FXD400). Globally, the most common ferrite grades are Y30 (Feroba2, Fer2, C5 and HF26/18) and Y30H-1 (FXD380, Feroba3, Fer3, C8). Y30 is a standard choice when it comes to magnet systems such as overhead magnets and separator magnets. The Y30H-1 is also good when it comes to separators but is often seen in applications such as speakers and sometimes motors. (Both these materials have similar Remanence but Y30H-1 has higher HcB and HcJ (Coercivity - the magnet's ability to resist demagnetization forces, thus how difficult it is for the magnet to be affected by other magnetic fields / demagnetization).
The strength of a magnet can be found in the magnet specification known as BHmax, which is the maximum energy density of a magnet. This is defined in Mega Gauss Oersteds, or MGOe. On a Magnetic Demagnetization Curve this is the highest point of the magnet’s strength, or the magnet’s maximum energy product.
Ferrite magnets have a good magnetic field and good strength but, in terms of volume, they are not as powerful as magnetic materials such as NdFeB or SmCo. You can compare the strength of different magnet materials by their BHmax values - MGOe. For example, ferrite go from approx 3 - 5 MGOe. Neodymium go from approx 30 - 50 MGOe, which means NdFeB magnets are about 10 times stronger than ferrite in equal volume. When choosing or defining your magnet, keep in mind that the higher the MGOe number, the stronger the magnet.
Ferrite magnets are manufactured in many shapes and sizes. But you cannot get exactly the geometry you want on a ferrite magnet. What limits this is the grinding process - it is not possible to process the ferrite material with wire sparking because it is electrically isolated. Therefore, the standard shapes are: Block, Cylinder, Ring and Segment. Other forms may require tools to produce, and then fees are added for the production of these tools.
A few properties of ferrite magnets
Tolerance: +/-3% is common. The tolerance depends on the shape and size of the magnet. We do not always have the tolerance printed on the article card. If there is a specific article you wish to know the tolerance on, contact us.
Corrosion resistance: Ferrite is a very good corrosion-resistant material, they do not rust or decay in water. This is because they are mainly made of oxides of iron, strontium and barium. This makes ferrite a very good option for outdoor applications.
Working temperatures: Like we talked about a bit above, maximum working temperature for ferrite is normally 250°C, but can sometimes be used up to 300°C (this depends on the grade and geometry of the magnet). Even the lowest temperature depends on the magnet's specification. It can go from a minimum temp of -60°C, but can also be a minimum of 0°C - This is not common. Min -60°C to Max 250°C is most common.
Note that ferrite magnets are not the same as soft ferrites.
Below you can see a table with all the Neodymium grades Hyab can offer. Contact us if you would like to know more about the different grades. We help clients daily with customized solutions for their project.