Abstract: A method of producing powder metal articles includes compacting and sintering powder metal to produce a shaped powder metal preform having at least one exposed surface to be surface densified which extends parallel to an axis of the preform between a free end and a blind end adjacent a transverse portion of the preform. The blind surface is cold worked by forcing a shaped densifying tool axially along the surface in a direction from the free end toward the blind end, and then reversing the direction of the tool toward the free end to densify a layer of the material at the exposed surface. In addition to the blind surface, the article can include one or more additional surfaces that can be densified in the same manner in a simultaneous operation.

Abstract: A method of producing powder metal articles includes compacting and sintering powder metal to produce a shaped powder metal preform having at least one exposed surface to be surface densified which extends parallel to an axis of the preform between a free end and a blind end adjacent a transverse portion of the preform. The blind surface is cold worked by forcing a shaped densifying tool axially along the surface in a direction from the free end toward the blind end, and then reversing the direction of the tool toward the free end to densify a layer of the material at the exposed surface. In addition to the blind surface, the article can include one or more additional surfaces that can be densified in the same manner in a simultaneous operation.

Abstract: A multi-stage forming tool for densifying the outer perimeter of post-sintered powder metal preforms includes a series of axially spaced die plates having different sized die openings arranged from largest to smallest. An oversized powder metal preform it is forced by a punch through the successive die openings causing the outer perimeter material to be displaced and densified. The space between successive dies allows for elastic recovery of the preform to maximize the compressive stress imparted to the preform at each die stage. A high density, high strength powder metal component results which is suitable as a replacement for wrought components in high strength applications such as transmission gears.

Abstract: A wrought or powder metal gear preform is mounted for rotation about a first axis and then driven in meshing engagement with a roll forming die supported for rotation about a second axis transverse to the first axis. The roll forming die includes a helical worm thread that moves radially as well as axially across the face of the preform teeth to displace the material of the preform. In the case of a powder metal preform, displacement of the material acts to densify the teeth, whereas in the case of a wrought preform the gear teeth are burnished. The preform and roll forming die are separately driven to control densification.

Abstract: A wrought or powder metal gear preform is mounted for rotation about a first axis and then driven in meshing engagement with a roll forming die supported for rotation about a second axis transverse to the first axis. The roll forming die includes a helical worm thread that moves radially as well as axially across the face of the preform teeth to displace the material of the preform. In the case of a powder metal preform, displacement of the material acts to densify the teeth, whereas in the case of a wrought preform the gear teeth are burnished. The preform and roll forming die are separately driven to control densification.

Abstract: A method of densifying the wall of an opening in a powder metal preform includes forcibly extending a densification tool through the opening having a plurality of radially enlarged forming portions arranged in axially spaced succession from smallest to largest which act to enlarge and densify the preform material and impart beneficial compressive stresses. The space between successive forming portions enables the preform material to recover elastically between adjacent forming sections to maximize induced compressive stresses.