To stably manufacture a sintered parts of high sintering density by a pressing method by granulating powder small in mean grain size (fine powder) into granulated powder, setting the mean grain size to be approximately on the same level as that of the powder large in mean grain size (general powder), and mixing the granulated powder with the general powder to be formed and sintered.
Raw fine powder and raw general powder are metallic powders formed of iron, iron alloy, nickel, etc. The fine powder is preferably 1-100 μm in mean grain size. The fine powder is fed to a granulating device, a binder such as polyvinyl alcohol and polyvinyl pyrolidone is added thereto, and mixed therein to be granulated. A mixing granulating method is preferably of a rolling type in which a rotary pan, a rotary cylinder or a rotary cone is used. The binder is removed simultaneously with a lubricant in a degreasing process after the mixed powder is formed. A parts of the sintering density of ≥93% can be easily and inexpensively manufactured by the pressing method.
WATANABE ATSUSHI
KATO KANEYUKI
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