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MAGNETIC FIELD PRESSING TECHNOLOGY

The remanence of VACODYM® and VACOMAX®  magnets can be greatly influenced by the choice of the pressing method (see schematic diagrams). An external magnetic field H in a specific phase of compaction p of the powder leads to the alignment of the magnetic moments of the anisotropic powder particles. In this combination, the relative orientation of the created field to the pressing direction greatly influences the degree of alignment that could be achieved.

Pressing of parts in axial field (AP)
Pressing of parts in transverse field (TP)
Isostatic Pressing of blocks (HR)

By using various pressing methods in the magnetic field anisotropic rare earth magnet powders will get different perfectness of magnetic orientation.

The best magnetic homogeneity, highest remanence, good dimensional accuracy and precise tool dimensioning are the goals of magnetic field pressing technique.

Isostatic pressing (HR) and pressing in the transversal field (TP) lead to a better degree of alignment and thus a higher remanence than pressing in the axial field (AP).

The AP process facilitates RE magnets in a wide variety of shapes to be produced particular economically and with a high degree of uniformity.

Compaction homogeneity of the powder alignment determine the dimensional stability that can be achieved after the sintering process. VACUUMSCHMELZE's know-how allows the pressing density or orientation to be optimised and thus minimise sintering distortion and mechanical tolerances.

But the pressing of magnets to the final dimension (Netshape), taking account of anisotropic sintering shrinkage, makes high demands on the pressing technique, but it is the most efficent manufacturing process for VACODYM or VACOMAX magnets.

The manufacture of "composite" magnets on the basis of rare earths with plastic binders makes different demands on the pressing technique than the manufacture of conventional sintered magnets. The magnetic alignment of the powder results similar to that of sintered magnets. Bonded magnets, however, need high compaction pressures to achieve an adequate packing density and, thus, remanence. Bonded magnets achieve final dimensions with close tolerances directly by shaping without any subsequent working. In that way they often allow a cost-effective manufacture of a variety of shapes.

hardmagnetic parts

Last update: 03.12.2012

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