Connecting rod for internal combustion engine

A method of manufacturing a connecting rod for an internal combustion engine, said method comprising:

• forming a connecting rod base material by a casting or forging process;
• machining an inner surface of a base material hole by a cutting or grinding process, said machining including machining a cylinder inner-surface portion and a tapered inner-surface portion;
• depositing a coating material on the inner surface of the base-material hole;
• and
• machining the coating material such that a portion of the coating material covering the cylinder inner-surface portion has a uniform thickness, while a portion of the coating material covering the tapered inner-surface portion includes a portion which increases in material thickness in an axially outward direction, whereby the coating material includes a first coating portion deposited on the cylinder inner-surface portion and having an inner face with an approximately constant inner diameter, and a second coating portion deposited on the tapered inner-surface portion to adjoin the first coating portion and gradually increasing in material thickness in the axially outward direction,
• wherein the coating material includes a third coating portion being continuous with an axially outward side of the second coating portion and having an inner peripheral face radially enlarged in the axially outward direction,
• wherein the tapered inner-surface portion of the base-material hole has a diameter expansion rate in an axially outer region set to be larger than a diameter expansion rate in an axially inner region, and
• wherein the tapered inner-surface portion of the base-material hole comprises a tapered surface with a plurality of stages in which the tapered angle is chanted in multi-stages.