Ferrites, Ferrite Magnets, Hard and Soft Ferrite Magnet, Ferrite Cores, Sintering Permanent Ferrite Magnets, Injection Molding Ferrite Magnet China Supplier
A ferrite (Ferrite Magnets) is a type of ceramic compound composed of iron(III) oxide (Fe2O3) combined chemically with one or more additional metallic elements. They are both electrically nonconductive and ferrimagnetic, meaning they can be magnetized or attracted to a magnet. Ferrites can be divided into two families based on their magnetic coercivity, their resistance to being demagnetized. Hard ferrites have high coercivity, hence they are difficult to demagnetize. They are used to make magnets, for devices such as refrigerator magnets, loudspeakers and small electric motors. Soft ferrites have low coercivity. They are used in the electronics industry to make ferrite cores for inductors and transformers, and in various microwave components. Ferrite compounds have extremely low cost, being made of iron oxide (i.e. rusted iron), and also have excellent corrosion resistance. They are very stable and difficult to demagnetize, and can be made with both high and low coercive forces.
Composition and Properties
Ferrites are usually non-conductive ferrimagnetic ceramic compounds derived from iron oxides such as hematite (Fe2O3) or magnetite (Fe3O4) as well as oxides of other metals. Ferrites are, like most of the other ceramics, hard and brittle.
Many ferrites are spinels with the formula AB2O4, where A and B represent various metal cations, usually including iron Fe. Spinel ferrites usually adopt a crystal motif consisting of cubic close-packed (fcc) oxides (O2−) with A cations occupying one eighth of the tetrahedral holes and B cations occupying half of the octahedral holes. If one eighth of the tetrahedral holes are taken by B cation, then one fourth of the octahedral sites are occupied by A cation and the other one fourth by B cation and it is called the inverse spinel structure. It is also possible to have mixed structure spinel ferrites with formula [M2+1−δFe3+δ] [M2+δFe3+2−δ]O4 where δ is the degree of inversion.
The magnetic material known as “ZnFe” has the formula ZnFe2O4, with Fe3+ occupying the octahedral sites and Zn2+ occupy the tetrahedral sites, it is an example of normal structure spinel ferrite.
Some ferrites have hexagonal crystal structure, like barium and strontium ferrites BaFe12O19 (BaO:6Fe2O3) and SrFe12O19 (SrO:6Fe2O3).
In terms of their magnetic properties, the different ferrites are often classified as “soft” or “hard”, which refers to their low or high magnetic coercivity, as follows.
Various ferrite cores used to make small transformers and inductors
Ferrites that are used in transformer or electromagnetic cores contain nickel, zinc, and/or manganese compounds. They have a low coercivity and are called soft ferrites. The low coercivity means the material’s magnetization can easily reverse direction without dissipating much energy (hysteresis losses), while the material’s high resistivity prevents eddy currents in the core, another source of energy loss. Because of their comparatively low losses at high frequencies, they are extensively used in the cores of RF transformers and inductors in applications such as switched-mode power supplies and loopstick antennas used in AM radios.
The most common soft ferrites are:
Manganese-zinc ferrite (MnZn, with the formula MnaZn(1-a)Fe2O4). MnZn have higher permeability and saturation induction than NiZn.
Nickel-zinc ferrite (NiZn, with the formula NiaZn(1-a)Fe2O4). NiZn ferrites exhibit higher resistivity than MnZn, and are therefore more suitable for frequencies above 1 MHz.
For applications below 5 MHz, MnZn ferrites are used; above that, NiZn is the usual choice. The exception is with common mode inductors, where the threshold of choice is at 70 MHz.
In contrast, permanent ferrite magnets are made of hard ferrites, which have a high coercivity and high remanence after magnetization. Iron oxide and barium or strontium carbonate are used in manufacturing of hard ferrite magnets. The high coercivity means the materials are very resistant to becoming demagnetized, an essential characteristic for a permanent magnet. They also have high magnetic permeability. These so-called ceramic magnets are cheap, and are widely used in household products such as refrigerator magnets. The maximum magnetic field B is about 0.35 tesla and the magnetic field strength H is about 30 to 160 kiloampere turns per meter (400 to 2000 oersteds). The density of ferrite magnets is about 5 g/cm3.
The most common hard ferrites are:
Strontium ferrite, SrFe12O19 (SrO·6Fe2O3), used in small electric motors, micro-wave devices, recording media, magneto-optic media, telecommunication and electronic industry.
Barium ferrite, BaFe12O19 (BaO·6Fe2O3), a common material for permanent magnet applications. Barium ferrites are robust ceramics that are generally stable to moisture and corrosion-resistant. They are used in e.g. loudspeaker magnets and as a medium for magnetic recording, e.g. on magnetic stripe cards.
Cobalt ferrite, CoFe2O4 (CoO·Fe2O3), used in some media for magnetic recording.
Ferrite magnets (Ceramic magnets) are sintered permanent magnets composed of Barium or Strontium Ferrite. This class of magnets, aside from good resistance to demagnetization, has the popular advantage of low cost.
Ferrite magnets are very hard and brittle, and require specialized machining techniques. Moreover, they should be machined in an unmagnetized state. We are equipped to machine these materials to specifications.
Anisotropic grades are oriented in the manufacturing direction, and must be magnetized in the direction of orientation. Isotropic grades are not oriented and can be magnetized in any direction, although some degree of greater magnetic strength will be found in the pressing dimension, usually the shortest dimension.
Due to their low cost, Ferrite magnets enjoy a very wide range of applications, from motors and loudspeakers to toys and crafts, and are the most widely used permanent magnets today.
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 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 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 magnets are widely used in motors, magnetic couplings, for sensing, loudspeakers, holding-magnet systems, crafts, magnetic therapy, novelties, and toys.
We supply micro magnets in Alnico, NdFeB, SmCo, Ceramic FeCrCo with very tight tolerances as well as NdFeB micro magnets with high quality parylene cating, Ni, Ni black and gold-plated. These magnets are used many applications include industries as diverse as medical applications, medical devices, micro motors, and sensors. We can provide magnets in Neodymium […]
Strontium Barium Ferrite Magnets, Sr/Ba Ferrite Magnet, ferrite permanent magnets, Ferrite cores for electronics industry, Hard & Soft ferrite magnet, Sr/Ba Ferrite compounds for electronic inductors, transformers, and electromagnets Sr/Ba Strontium Barium Ferrite Magnets – Ferrite is a type of ceramic compound composed of iron(III) oxide (Fe2O3) combined chemically with one or more additional metallic […]
Sr/Ba Ferrite Magnet, Strontium ferrite magnets, Barium ferrite permanent magnets, Ferrite cores, Hard ferrite magnet, Sr/Ba Ferrite compounds Sr/Ba Ferrite Magnet – Ferrite is a type of ceramic compound composed of iron(III) oxide (Fe2O3) combined chemically with one or more additional metallic elements.They are both electrically nonconductive and ferrimagnetic, meaning they can be magnetized or […]
Bonded Injection Moulding Ferrite Magnet for Sensor, Permanent Ndfeb Plastic bonded sensor magnet, Ferrite injection bonded ring magnet, Bonded magnet Assembly China supplier Bonded Injection Moulding Ferrite Magnet for Sensor – Precise injection bonded ferrite magnets include Anisotropic and isotropic magnet. Isotropic magnets mainly used in colour TV, and Anisotropic magnet mainly used in the […]
FC-280 Ferrite Industrial Motor Magnets, Arc Ferrite Motor Magnet, magnetic tile, wholesale cheap arc segment ferrite magnet, Y25-Y30BH Arc Hard Ferrite Magnet for PSC Motors, ceramic motor magnets FC-280 Ferrite Industrial Motor Magnets Feature: Name: 5812P magnetic tile Width of chord: 17 ±0.2mm Axis height: 16.6 ±0.3mm Wall Thickness: 3.6 + 0.1mm Arch height: 7.9 […]
5812P Arc Ferrite Motor Magnet, Arc Ferrite Magnet For Industrial Motors, magnetic tile, wholesale cheap vibro motors arc segment ferrite magnet, ceramic motor magnets 5812P Arc Ferrite Motor Magnet Feature: Name: 5812P magnetic tile Width of chord: 30 + 0.3mm Axis height: 45 +0.3mm Wall Thickness: 3.85 + 0.1mm Arch height: 11.7mm Internal arc: R13mm […]
Injection Ferrite Seat Motor Sensor Magnet, Sensor Magnets for Car Adjusting Motor Seats, Bonded Ferrite PPS Automotive Seat Motor Magnet, Injection Moulding Ferrite Magnet for Automotive Seat Motor China supplier Injection Ferrite Seat Motor Sensor Magnet Features: Coating PPS+Epoxy Material Ferrite+ binder resin Size Customize Shape Customize as client’s drawing Density 3.3-3.8g/cm³ Packing Standard sea […]
Car Cooling Water Pump Magnets, Ferrite PPS Automotive Water Pump Magnet, Ferrite Magnet For Water Pump Generator, Water Pump Bonded Ferrite Magnet, Automotive water pump injection ferrite magnets China supplier Car Cooling Water Pump Magnets Features: Material Bonded Magnet Coating PPS+Epoxy Size 1-200mm Automotive water pump is an essential component in engine’s cooling system. The […]
OEM Plastic Ferrite Injection Magnets, Customized Multi-pole Injection Plastic Ferrite Bonded Industrial Permanent Magnets, Injection Molded Plastic Ferrite Magnets for Motor Rotor Pa6 / Pa12 / PPS OEM Plastic Ferrite Injection Magnets Material: The cheapest magnetic material, main contents including ferric oxide,. Magnet Shape: special shapes and more. Customized shapes are available Introduction: A low […]
Pa6 / Pa12 / PPS Injection Ferrite Permanent Magnets, Customized Multi-pole Injection Plastic Ferrite Bonded Magnets, Micro Injection Molded Plastic Ferrite Magnets for Motor Rotor, OEM injection magnets for industrial Pa6 / Pa12 / PPS Injection Ferrite Permanent Magnets Features: Material Pa6/Pa12/PPS Size Custom-made Density 3.8 g/m3 Max Working Temperature 80°C Lead Time About 30 […]
Customized Bonded Multi-Polar Injection Plastic Ferrite Magnets, Micro Custom Injection Molded Ferrite Magnets for Rotor, Pa6 / Pa12 / PPS Injection Moulding Ferrite Motor Magnet Customized Bonded Multi-Polar Injection Plastic Ferrite Magnets Features: Material Pa6/Pa12/PPS Size Custom-made Density 3.8 g/m3 Max Working Temperature 80°C Lead Time About 30 days Used Industry machinery Plastic magnetic rotor […]
Custom-made Injection Ferrite Magnets for Rotor, Pa6 / Pa12 / PPS Injection Moulding Ferrite Magnet for Rotor, raw material bonded ferrite magnets, High temperature stability injection molding ferrite magnet Custom-made Injection Ferrite Magnets for Rotor Features: Material Pa6/Pa12/PPS Size Custom-made Density 3.8 g/m3 Shaped Ring, Custom-made Max Working Temperature 80°C Lead Time About 30 days […]
Injection Molded Plastic Ferrite Ring Magnet for Magnetic Encoder, Magnetic Ring Injection Plastic Ferrite Motor Encoder Magnets, Multi-Poles Injection Ferrite Ring Encoder Permanent Magnet, Injection plastic-bonded ring magnet Injection Molded Plastic Ferrite Ring Magnet Part No. HS-IFM03 Type: Permanent Composite: Plastic Magnet Shape: ring magnet Application: Industrial Magnet, Motor encoder Material: Plastic + magnet Plastic: […]
Ring Injection Ferrite Encoder Magnets, Injection Moulded Plastic Ferrite Magnet Motor Encoder Magnet Ring, Multi-Poles Injection Ferrite Ring Encoder Magnet, Injection plastic-bonded ring magnet Ring Injection Ferrite Encoder Magnets Part No. HS-IFM02 Type: Permanent Composite: Plastic Magnet Shape: ring magnet Application: Industrial Magnet, Motor encoder Material: Plastic + magnet Plastic: PPS, Nylon etc. Magnet: Neodymium […]
6 Poles Injection Ferrite Ring Encoder Magnet, Magnetic Ring Encoder Magnets, Magnetic encoder, Injection plastic-bonded ring magnet 6 Poles Injection Ferrite Ring Encoder Magnet Features Part No. HS-IFM01 Injection plastic-bonded magnet is a new kind of composite permanent-magnetic material with features of flexible shaping, dimensional precision, adjustable magnetic properties, fine coherence, composite molding, elastic magnetization […]
Rotor Ferrite Magnets Assemblies, Ferrite/Ceramic Permanent Magnets, Customized Ferrite Ring Magnet Rotor Component, Motor Magnet Magnetic Rotor Parts, pre-assembled magnetic motor parts with glued ferrite permanent magnets, multipole ring magnets for rotor, magnetic assemblies At HSMAG, your one-stop sourcing solution for Rotor Ferrite Magnets Assemblies, we carry a large selection of Hard Ferrite/Ceramic Magnets known […]
Plastic Injection Ferrite Water Pump Magnet, Injection Moulding Ferrite Magnet for Water Pump, Injection Plastic Ferrite Magnet, Isotropic ferrite magnets and Anisotropic ferrite magnets The specification of Plastic Injection Ferrite Water Pump Magnet 1)Material:Ferrite powder,strontium,barium ,etc. 2)Characteristics: * Low cost, high-energy, good electric insulation and excellent resistance to demagnetization. * High coercive force, high electric […]
Injection Ferrite Magnet, High Quality Injection Moulding Ferrite Magnet, Injection Plastic Ferrite Magnet, Isotropic ferrite magnets and Anisotropic ferrite magnets The specification of Injection Ferrite Magnet 1)Material:Ferrite powder,strontium,barium ,etc. 2)Characteristics: * Low cost, high-energy, good electric insulation and excellent resistance to demagnetization. * High coercive force, high electric resistance, long-time stability, and economical price. 3)Type:Isotropic […]
Segment Ferrite DC Motor Magnets, Segment Ceramic Magnet For DC Motors, Ferrite Sectors, Hard Sintered Ferrite Arc Magnets China Supplier & Factory Ferrite DC Motor Magnets – Ceramic Magnets for DC motors depend a lot of the application. It is always a balace between technology and price. The steps needed to select properly the type […]
High Strength Ceramic Segment Magnets, Hard Ceramic Arc Magnets, Motor Ferrite Permanent Magnets, Arc Tile Segment Ferrite Magnet for Motors High Strength Ceramic Segment Magnets Features: Part No.: HS-FAM Material: Ferrite / Ceramic Shape: ARC, SEGMENT As the request of clients Sintered Ferrite Segment Ceramic Magnet Electric Motor Rotor Magnets China Factory Specification: 1.Low cost, […]