US Patent 7931856 Method of manufacturing crankshaft bushing

A method of forming a crankshaft bushing or similar component is provided. A compaction die is provided having an axial, generally cylindrical internal opening. An upper and a lower punch are provided with exterior surfaces corresponding to the internal opening of the compaction die. An upper core rod passes through an axial opening in the upper punch. A lower core rod passes through an axial opening in the lower punch. The upper core rod and the lower core rod each may have a generally flat external surface section. A metal powder is compacted in the compaction die by the combined action of the upper and lower punches and the upper and lower core rods.