Ferrite
Ceramic Magnets
CER-S, ISOCER

Ferrite

The birth of this family of magnets was announced in 1952 (isotropic) and 1954 (anisotropic). Also known as Ceramic Magnets, they are mainly Strontium based (SrFe2O3), manufactured with Strontium Carbonate additive to increase performances from the obsolete Barium based (BaFe2O3). The process consists in milling the raw materials compound hexaferrite into single crystals approximating a single domain in size. For highest grades particles are even smaller than 1. Then the powder is wet or dry pressed in a die under the influence of a magnetic field (for anisotropic grades). After that, the pressed compacts are sintered in ovens at high temperatures then finished.

Their good coercive force results from high crystal anisotropy of Strontium iron oxide. However, isotropic parts can also be produced where a simple and easy multi-pole magnetization is required.

Nowadays, Ferrite is the cheapest magnetic material available with the lowest cost/energy ratio. The most common shapes are simple, such as blocks, cylinders, rings and arcs. The dimensional tolerances from the mould are quite wide and it must be ground, usually on the magnetization axis, to obtain tight mechanical tolerances. Very hard and brittle, Ferrite is not conductive and has high resistance against corrosion, acids, salts, lubricants and gases.

Injection & Compression Moulded Magnets
Ferrite and NdFeB
I-CER, I-REN, C-REN

Injection & Compression Moulded Magnets

Special magnet form obtained by amalgamating powders to a flexible binder, usually polyethylene (CPE) or nitrile rubber (NBR). The common processes are calendering (anisotropic) or extrusion (isotropic) and the typical shapes are strips, sheets or rolls. While for calendering process no specific tooling is necessary, for the extrusion process this will depend on the final required profile.

The traditional ferrite based material has recently seen the growth of the high-energy NdFeB based grades, obtained by calendaring and anisotropic. However, the presence of rare earth metal powder reduces the temperature capability.

It is a magnetic material that can be easily cut, punched, stamped, twisted, coiled, coloured and machined; therefore it is often used in signs, promotional and decorative items. Its flexibility allows its application on curved surfaces and the most common magnetization is multi-pole on one face.It can be supplied with a coloured PVC or self-adhesive side and no corrosion protection is required.

NdFeB
Neodymium Iron Boron
REN

NdFeB

Sintered Neodymium-Iron-Boron was introduced in 1980. This anisotropic material offers the highest Energy Product (BHmax) commercially available today, in a wide range of shapes, sizes and grades.

Typical applications include high performance sensors and ignition coils, miniaturized DC motors, linear actuators, MRI, wind energy turbines, magnetic separation and lifting devices.The latest grades have reached Energy Product levels of 53MGOe (422kJ/m3) and HcJ values greater than 35kOe (2786kA/m), permitting applications up to 220°C and more. But even at lower temperatures, depending on the magnet’s geometry and the magnetic circuit design, a certain level of irreversible losses may occur during the very first operating cycles, in addition to the reversible losses given by the Temperature Coefficient of Br (-0,12%/°C). Despite constant improvement, NdFeB remains susceptible to corrosion, therefore a protective coating is always recommended.

Depending on the operating environment, CIBAS can offer the more appropriate coatings such as Passivation, Zn, Ni+Cu+Ni, Epoxy resin and many others. NdFeB magnets follow a powder metallurgy manufacturing process where the alloy is melted from the raw materials, crushed, milled, pressed under orientation field (generally blocks or cylinders), sintered and machined to the final shape by cutting and grinding processes allowing high precision tolerances.

There are generally no specific tooling costs associated and further operations are the coating and the magnetization. Because of the extremely strong magnetic field, special cares are mandatory while handling and assembling magnetized parts.CIBAS provides a complete range of sintered NdFeB grades, both standard and fully customized. You can also find the latest developments in the compression (C-REN) or injection bonded (I-REN) NdFeB magnets in our dedicated datasheet.

SmCo
Samarium-Cobalt
RES

SmCo

Samarium-Cobalt magnets were developed in 1960 while researching a new magnetic material based on Fe, Co, Ni and Rare Earth alloys. They are produced by pressing powdered alloys to shape under orientating field, then sintered. It is typically anisotropic (unique magnetization axis) and two different compositions are available: SmCo5 and Sm2Co17 (with higher coercivity).

Among the rare-earth magnets, it has the best Br temperature coefficient (-0,035%/°C) granting the absolute higher available induction above 150°C working temperature. Despite a higher cost than other magnetic materials, SmCo provides an outstanding combination of high energy, thermal stability and corrosion resistance. Protective coatings are generally not required except for particular applications.

The typical final shapes such as blocks, cylinders, rings and arcs are obtained by cutting and grinding processes of pressed standard blocks or unitary compression pre-moulded part. Extremely fine tolerances can be obtained although, because of its high brittleness, it has to be handled and assembled with care to avoid chips and cracks.

AlNiCo
Aluminium, Nickel, Cobalt and Iron alloy
ALCAST, ALSINT

AlNiCo

AlNiCo (Aluminium, Nickel, Cobalt and Iron alloy) is obtained by casting process, shaped in cheap phenolic resin sand moulds. It is the oldest and most stable magnetic material, with temperature coefficients of -0,03%/°C (Br) and -0,02%/°C (HcJ). It can operate in environments up to 500 °C with a very good resistance against corrosion, therefore coatings are seldom required. For multi-pole magnetizing patterns isotropic material is available. Higher energy anisotropy is obtained by external coils orientation during the thermal treatment.

Because Alnico magnets are coarse-grained, hard and brittle, conventional machining such as drilling is not possible, however, finished surfaces may be obtained by grinding.

A unique characteristic of AlNiCo is its very high residual induction vs. a very low coercivity, therefore in most applications it can be effectively used by magnetizing after assembly in the magnetic circuit, and it is specially recommended in applications where only a temporary demagnetization is required (magnetic chucks, lifters...). For small sized models, due to the typical porosity of the casting process, sintered versions (ALSINT) are available upon request.

Flexible Magnets
Ferrite and NdFeB
PLASTOFER ANI/ISO, PLASTOREN

Flexible Ferrite & NdFeB 

Probably one of the most significant among the latest developments in magnetic materials, plastic-injected and compression moulded magnets are obtained from Ferrite or NdFeB powder in conjunction with a plastic or resin binder. Hybrid compounds can also be developed on request.

The typical plastic injection process permits complex miniaturized shapes with high precision, and direct moulding combined with other components such as metal inserts, shafts and rotors is possible. Only the Ferrite based compounds offer anisotropic versions and the orientation is obtained by external coils or by permanent magnets integrated in the mould.

The compression moulding still offers wide shaping possibilities and thanks to his isotropy it is unbeatable in miniaturized multi-pole configurations, eliminating the injection’s runners weight cost typical impact on small parts, where recycling possibilities are limited.

Additional machining is easy. In addition to the magnetizing versatility, the composition flexibility allow a variety of magnetic properties combinations, and maximum operating temperatures are generally satisfactory for most of the applications.

These magnets are particularly recommended for high precision applications such as computers, servo-motors, instruments, medical devices, and are often combined with metal parts. The NdFeB compounds are still susceptible to corrosion, therefore a protective coating is generally required and for this specific material we recommend epoxy resin.