Permanent magnets with intermetallic, ferro-magnetic composition of rare earth materials, in particular samarium (Sm) and cobalt (Co) (further elements are iron (Fe), copper (Cu) and zirconium (Zr)) are anisotropic and are produced by a powder metallurgical sintering process. The main characteristic of RECo magnets is a very high level of energy density. This enables the miniaturisation of systems when compared with ferrite magnets or a higher performance level for systems of similar sizes. Due to their very high coercive field strength, magnets of SmCo are extremely resistant to demagnetisation and electro-magnetic counter fields. Samarium-Cobalt magnets are very hard and brittle, therefore careful machining and handling is advisable to avoid fractures and cracks.
The alloy preparation is done by melting the alloy and grinding the prematerials to a mono crystalline powder with a grain size of below 5 µm. The magnetic alignment is achieved by pressing under the influence of a magnetic field. Depending on the orientation and direction of pressing compared with the magnetic field, the alignment and thus the magnetic values will vary considerably. During the so called cross field pressing, the magnetic field and the direction of pressing should be at right angles. This results in maximum energy density and optimum remanence. Axial pressing (press direction and magnetic field are parallel) results in lower values (approximately 10% lower Br and 20% lower (B·H)max values). This should, however, meet customer requirements in most cases and result in more cost effective production of big volume quantities. Magnet sintering is carried out in an inert gas atmosphere or in a vacuum at temperatures between 1100 – 1200 degrees C. Sintering density is between 8.2 – 8.5 g/cm³. Finally the magnets are heat treated between 500 – 900 degrees C. Further production stages are machining, grinding, system assembly, etc.
Our Product Range:
Our range comprises a wide selection of Samarium-Cobalt materials with differing magnetic properties. They permit material selection tailored to individual application requirements.
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