PURPOSE: To produce high-accuracy sintered parts having wear resistance and toughness by subjecting powder to molding, sintering, hardening and tempering then to sizing at the time of producing the sintered parts.
CONSTITUTION: The material powder of the sintered parts is molded and sintered and is then coned to increase the material density to about ≥7.2g/cm 2 . A carburization preventive material is hen coated to unnecessary points and the powder is subjected to partial carburizing, then to hardening and tempering. The powder is further subjected to a phosphoric acid film treatment to improve the sizability of the sintered parts; thereafter, the sintered parts are sized. The high-accuracy sintered parts useful for a cam ring of a vane pump, etc. are thereby obtd.