Frequently Asked Questions Concerning Ceramic & Ferrite Magnets

1. Q: what are ferrite/ceramic magnets?
A: Ferrite magnets, also called ceramic magnets, are a large class of magnets that include chemical compounds such as hematite (Fe2</SUB<O3) and magnetite (Fe3O4), which is the most magnetic naturally occurring mineral on Earth. Ferrite & ceramic magnets are the simplest type of magnets compared with other more sophisticated magnets like Alnico magnets or neodymium magnets (rare-earth magnets). Ferrite/ceramic magnets can be classified into two categories based on their manufacturing techniques: sintered ferrite magnet and bonded ferrite magnet.

2. Q: How to screen magnetic field?
A: Normally, we use the iron sheet to screen the magnetic field. A magnetic shielding need high permeability material, the Iron Nickel Alloy which has the very high magnetic permeability is the material can meet such standard. When the magnetic field we need to shield is very strong; if only use single shield material, it either can not meet shielding demand, or will be saturated. On this occasion, one solution is to increase the thickness of the material; and the more effective solution is to use the combination shielding assembly, which is to leave airspace between one shielding and the other shielding. That is to say, Filling with any permeability material (such as aluminum) in the airspace for supporting when put one shielding into another. The effect of using combination shielding assembly is much higher than single shielding, and the combination shielding assembly can decrease the magnetic field to very low degree.

3. Q: What attention should we pay when store and deliver ceramic & ferrite magnets?
A: When store ceramic & ferrite magnets, the room needs to be dry and ventilated; otherwise, humid environment is easy to make the magnet rusted. Environment temperature can not be higher than their max working temperature either. Products without coating can paint appropriate antirust oil to reduce rusting opportunity. Magnetized magnets also should put far way from object which is sensitive to magnets, such as magnetic disc, magnetic card, tape, computer screen, watch and etc. Since ceramic & ferrite magnets are fragile, you need to make sure the magnets would not be impacted during delivery, coating and assembling. In any improper way, it would cause damage or split. Ceramic & ferrite magnets should be shielded during delivery, especially, when shipped by air, they must be shielded completely.

4. Q: What attention should we pay when handling magnets?
A: Make sure the workplace is clean when using ceramic & ferrite magnets; otherwise, it is easy to absorb scrap iron or some small particles, which will affect the function of the magnet. And when handling small size magnets, pay attention to avoid knocking against breakage. Pay attention to personal safety and protection when dealing with large size magnets.

5. Q: How to judge the grades of magnets?
A: There are three main parameters for you to judge the grades of magnets. The first parameter is residual magnetism (Br), unit at induction Gauss, which is the magnetic flux density after remove magnetic field from the saturated state. According to the residual magnetism, you can know how strong magnetic field of the magnets. The second parameter is coercive force (Hc), unit at Oversets, which put a magnet in reverse additional magnetic field, and the magnetic force will disappear when additional magnetic field increased to certain degree. We call the ability to resistance additional magnetic field as Coercive Force, which represents the ability of the demagnetization. The third parameter is magnetic energy product ((BH) max), unit at Gauss-Oersteds, which is the magnetic energy, occurred for certain volume material and is the physical quantity weighing the ability to store the magnetic energy.

6. Q: What are TDK ceramic & ferrite magnets?
A: A series of Br material, which arrange from the FB1 isotropic type to wet anisotropic FB9 type. TDK ceramic & ferrite magnets can be used in various applications. Dry anisotropic FB3 material has the best cost and can be used to produce magnets in various complex shapes which widely used in micro-generator, while wet anisotropic FB4~FB9 material can be used to produce magnets with high Br and high Hc.

7. Q: What is ¡°permanent ferrite¡± and ¡°soft ferrite¡±? What is their application?
A: After magnetized, the strength of the magnetic field for permanent ferrite is very high, and can remains for long time. Normally, it used as material for permanent magnets, such as speaker magnets. While for the soft ferrite, the strength of magnetic field becomes small or even no longer existing when the magnetic field for magnetization disappeared. Soft ferrite used as choke coil or magnetic cores for intermediate frequency transformer.

8. Q: What is the characteristics and application of ferrite/ceramic magnet?
A: Ferrite/ceramic magnet is a metal oxide which has the ferromagnetic. As to characteristic of electrical, the resistibility of ferrite is larger than metal and alloy material, and it has higher dielectric performance as well. Ferrite/ceramic magnet¡¯s magnetic performance has high magnetic permeability when used in high frequency applications. Therefore, ferrite/ceramic magnet has become a nonmetallic magnetic material which is widely used for high frequency elv field.

  E-mail: bigmagnet@china--magnet.com
Head Office

Room No. 705-707, Tower A Century Holiday Plaza,
No. 9030 Shennan Rd., OCT, Nanshan District, Shenzhen , China .
Tel: (86)755 26923096
Fax: (86)755 26915592