Abstract: A cast metal connecting rod of the type used in a reciprocating piston engine has a beam section between two end sections. The beam section and the end sections are integral with one another and are at least partially made of a cast metal material. At least the beam section of the connecting rod includes an insert made of a sintered powder metal material. The insert is at least partially encapsulated by the cast metal material of the connecting rod. The insert reinforces the connecting rod and can help match characteristics of surrounding or mating parts of the engine that are made of materials more similar to the material of the insert than the cast metal of the connecting rod. The cast metal material, for example aluminum alloy, of the connecting rod can also provide localized regions of high machinability where needed.

Abstract: A high performance main bearing cap has particular surfaces densified for improved fatigue crack resistance. The surfaces densified are the bolted face inside of a perimetral margin and outside of bolt head interface areas around the main bolt holes, the surfaces of the main bolt holes and the side bolt hole threads. Preferred methods of densification are single needle programmable pattern peening of the bolted face peened area, over-burnishing of the bolt holes, and forming the threads rather than cutting them for the side bolt threads.

Abstract: A high performance main bearing cap has particular surfaces densified for improved fatigue crack resistance. The surfaces densified are the bolted face (F) inside of a perimetral margin and outside of bold head interface areas around the main bolt holes (B), the surfaces of the main bolt holes and the side bolt hole threads (S). Preferred methods of densification are single needle programmable pattern peening of the bolted face peened area, over-burnishing of the bolt holes, and forming the threads rather than cutting them for the side bolt threads.

Abstract: A main bearing cap (A′) made of powder metal has a body portion (Y) made from one powder metal material (Q), and a bearing arch portion (H), foot joint face portions (S) and/or wings (W) made of a different powder metal material (P). The material (Q) of the body portion (Y) is harder than the material (P) of the other portions (H, S, W), and the material (P) of the other portions (H, S, W) is relatively machinable. For the bearing arch portion (H), the machinability of the material (P) approximately matches the machinability of the bearing support structure (B) to which the bearing cap (A′) is assembled to produce a good quality bore and longer tool life during line boring. The bearing arch material (P) may be a bearing material.

Abstract: A powder metal main bearing cap has integral dowels at its adjoining face around bolt holes and tooth projections surrounding the dowels. The dowels are force fit into counterbores in the engine block and the teeth bite into the metal of the block around the bolt holes to inhibit fretting wear. Elongated bolt holes can be formed in the main bearing cap to accommodate a splayed joint, with the bolt head supporting face of the cap at an oblique angle to the hole. The bearing cap can be first pressed into the engine block so as to assure indentation by the teeth and insertion of the dowels, followed by bolting.

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 method for high density long fill compaction of metallic powders uses a precisely temperature controlled mold and a dry sprayed lubricant which has the characteristic of softening on contact with the mold and smearing on the mold wall during compaction, yet on ejection not causing powder adherence.

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 sintered powder metal part is surface densified by surface heating followed by repressing. Surface heating is preferably done to a temperature which is just below the critical temperature where the steel alloy material of the part transforms from a ferritic to an austenitic microstructure. Repressing is in a die set which is smaller than the part by 10% of the surface heated depth. The hot skin is compressed and densified between the die and the cooler, and therefore less malleable core of the part Following surface densification, the part may be resintered and/or heat treated.