DUST CORE, METHOD OF PRODUCING GREEN COMPACT FOR CORE, PRESS DIE AND MOLD APPARATUS FOR MANUFACTURING DUST CORE, AND LUBRICATING LIQUID OF PRESS DIE FOR MANUFACTURING DUST CORE

摘要

PROBLEM TO BE SOLVED: To provide a dust core suitable for high frequency applications, in which insulation of soft magnetic powder particles in the surface layer is not destroyed when being extruded from a mold cavity.SOLUTION: The mold cavity of a mold is filled with soft magnetic powder, which is then compressed so that the density ratio of the soft magnetic powder becomes 91% or more thus molding a green compact, which is then extruded from the mold cavity. In such a method of manufacturing a dust core, a lubricant film containing a mold lubricant and insulating ceramics particles is formed on the inner surface, which slides on the green compact in the mold cavity before being filled with the soft magnetic powder. The extrusion sliding surface of the green compact has a surface layer of such a structure that the insulating ceramics particles are interposed between the particles of soft magnetic powder, and this green compact is used for composing the dust core.