Ferrite Magnets (Ceramic Magnets) - General Information!
The Ferrite permanent magnet is also known as a Ceramic Magnet and even as hard ferrite magnet. The name is interchangeable but they all refer to exactly the same material type. They are known as Ceramic Magnets because they are electrically insulating. Ferrite permanent magnets exist in two forms - Strontium Ferrite magnets and Barium Ferrite Magnets. The Strontium Ferrite Magnets is the most common.
Ferrite magnets are darker grey in colour and are often referred to as having a “pencil lead” appearance.
Ferrite / Ceramic permanent magnets are technically known as hard ferrite materials (when exposed to a brief external magnetic field, the material retains magnetism due to having high coercivity, Hc). They are not the same as soft ferrite materials as used in transformer cores (which do not retain magnetism after exposure to a brief magnetic field because soft ferrite materials have low coercivity). The high coercive force of Ferrite Magnets means they are classified as hard materials, like all the other permanent magnets.
Ferrite magnets are extremely popular due to their characteristics. Ferrite magnets are corrosion free – for long term performance they are superb; if looked after they are capable of exceeding most products lifecycles. Ferrite magnets can be used up to +250 degrees C (and in some cases up to +300 deg C). Ferrite magnets are also low cost, particularly in high volume production runs. We offer 30 grades of ferrite permanent magnet.
Ferritemagneti.com overviews Ferrite Permanent Magnet production and the characteristics of Ferrite Permanent Magnets. From this you should be able to determine your Ferrite magnet requirements (or we can help you if you need more assistance). And we can then provide you with a quotation for your magnet specification.
We supply Ferrite / Ceramic magnets globally to all industries, including Automotive, Aerospace, Military, Advertising, Design House, Electronic and Academic/R&D. If you require a bespoke Ferrite / Ceramic magnets or magnetic assembly, Technical Support or our Ferrite / Ceramic Magnet Technical Data Sheet, please contact us. If you need a quotation for an existing magnet shape or a bespoke shape, please contact us. As our production facility is in China, we offer a highly competitive price.
Pressing and Sintering:
Pressing and sintering involves pressing very fine ferrite powder in a die, and then sintering this pressed magnet. All fully dense Ferrite magnets are produced this way. Ferrite magnets can be wet pressed or dry pressed. Wet pressing yields better magnetic properties, but poorer physical tolerances. Generally, the powder is dry for grade 1 or 5 materials, and wet for grade 8 and higher materials. Sintering involves subjecting the material to high temperatures to fuse the pressed powder together, thus creating a solid material. Magnets produced through this process usually need to have some finish machining, otherwise surface finishes and tolerances are not acceptable. Some manufacturers extrude instead of press wet powder slurry and then sinter the material. This is sometimes done for arc segment shapes, where the arc cross-section is extruded in long lengths, sintered, and then cut to length.
Injection Molding: Ferrite powder is mixed into a compound and then injection molded in the same way as plastic.
Tooling for this manufacturing process is usually very costly. However, parts produced through this process can have very intricate shapes and tight tolerances. Injection molded ferrite properties are either lower or about the same as grade 1 Ferrite.
We are able to manufacture metal and other components of finished sub assemblies using our CNC machining facilities.
Assemblies using metal or other components and magnets can be fabricated by adhering magnets with adhesives to suit a range of environments, by mechanically fastening magnets, or by a combination of these methods. Due to the relatively brittle nature of these magnet materials, press fits are not recommended.
The corrosion resistance of Ferrite is considered excellent , and no surface treatments are required. However, Ferrite magnets may have a thin film of fine magnet powder on the surface and for clean, non-contaminated applications, some form of coating may be required.
Ferrite (ceramic) is brittle, and prone to chipping and cracking. Special machining techniques must be used to machine this material. We are fully equipped to machine these materials to your blueprint specifications.
Magnetizing and Handling
Ferrite (ceramic) magnets require magnetizing fields of about 10 kOe. They can be magnetized with multiple poles on one or both pole surfaces. No special handling precautions are required, except that large blocks of Ferrite magnets are powerful, and care should be taken to ensure that they do not snap towards each other.
Up to about 840F, changes in magnetization are largely reversible, while changes between 840F and 1800 F are re-magnetizable. For all Ferrite magnets, the degradation of magnetic properties is essentially linear with temperature. At 350F, about 75% of room temperature magnetization is retained, and at 550 F, about 50% is retained.
Common Applications for Ferrite Magnets
Ferrite (ceramic) magnets are widely used in motors, magnetic couplings, for sensing, loudspeakers, office, holding-magnet systems, crafts, magnetic therapy, novelties, and toys.