Abstract: A sintered powder metal part is prepared for machining by injecting grease into the surface of the part to be machined to a depth at least equal to the depth of machining. The grease is injected under very high pressure using repressing tooling by applying a certain volume of grease between the surface to be machined and the mating tool surface and applying pressure sufficient to uniformly inject the grease into the surface. A rim may be formed in the part adjacent to the surface which acts as a seal during grease injection and is compressed into the part.

Abstract: A unitary powder metal gear or sprocket (10) has a teeth region (16) which extends 2-5 mm below the tooth root diameter and a body region (14) radially inside of the teeth region (16). The teeth region (16) is pressed to a higher density than the body region (14) in a two chamber compaction die. The teeth region (16) is made of a sinter or induction hardening material, and the body region (14) is made of a liquid phase sintered material. Materials for the teeth (16) and body (14) regions are selected for compatibility by compacting them into a bimetallic strip (20, 22) with the teeth material (18) on one side and the body material (19) on the other side, sintering the strip (20,22) and observing the amount it bends.

Abstract: A bearing insert for being cast into an aluminum alloy engine block is made by a ferrous powder metal sintering process to make a skeleton structure which is permeable to the molten aluminum alloy in the block casting process. The insert is made of a material having a similar composition as the bearing cap so as to equalize machining and thermal expansion properties of the cap and block so as to provide improved roundness of the bearing in the machining operations for forming the bearing support and in operation of the engine.