Magnetic core and method for manufacturing same

A magnetic core manufactured by compression molding and subsequent thermal curing of an iron-based soft magnetic powder having a resin coating formed on particle surfaces thereof, wherein:

• said magnetic core is adapted for use with an induction hardening coil, said induction hardening coil is circular or rectangular, and in use, said magnetic core is fitted into a circular or rectangular frame;
• said iron-based soft magnetic powder having a resin coating formed on particle surfaces thereof in which said particle surfaces have been coated with an inorganic insulator, where said inorganic insulator is located between said iron-based soft magnetic powder and said resin coating, to form iron-based soft magnetic powder inorganic insulator coated particles;
• said inorganic insulator coated particles being sized to pass through a sieve having a mesh opening size of 106 μm, but not to pass through a sieve having a mesh opening size of 25 μm;
• the resin coating is an uncured resin coating formed by dry blending the iron-based soft magnetic powder, with a thermosetting epoxy resin containing a latent curing agent wherein said epoxy resin containing the latent curing agent has a softening point of 100° C. to 120° C., at a temperature equal to or greater than said softening point of the thermosetting resin and lower than the thermal curing initiation temperature of the resin;
• the compression molding is carried out by using a mold to produce a compression molded body;
• and
• the thermal curing is carried out at a temperature equal to or greater than the thermal curing initiation temperature of the thermosetting resin.