One-piece piston featuring additive machining produced combustion bowl rim and cooling gallery

A method of manufacturing a piston for an internal combustion engine, comprising the steps of:

• casting or forging a crown portion and a skirt portion as a single piece from a first material, the first material being selected from steel, cast iron, a cast iron alloy, aluminum, and an aluminum alloy;
• the casting or forging step including forming the crown portion to include a combustion bowl extending outwardly from a center axis to an upper end, a cooling gallery base wall extending outwardly from a base of the combustion bowl, and an outer rib with ring grooves extending upwardly from the cooling gallery base wall to present an open cooling gallery surrounding the center axis;
• the casting or forging step including forming the skirt portion from the first material to extend from the outer rib to a lower end and to surround the center axis, and forming the skirt portion to include a pair of pin bosses disposed opposite one another and each presenting a pin bore for receiving a wrist pin;
• forming a combustion surface between the upper end of the combustion bowl and the outer rib to close the open cooling gallery, wherein the combustion surface is formed from a second material having at least one of a higher thermal conductivity, higher erosion resistance, higher resistance to coking adhesion, and a higher oxidation resistance than the first material, and the second material is selected from stainless steel, a nickel-based alloy, and a nickel-chromium-based alloy;
• the step of forming the combustion bowl surface from the second material including an additive machining process, the additive machining processes including melting the first material along the upper end of the combustion bowl or along the outer rib, melting the second material, and depositing a plurality of layers of the melted second material on the melted first material;
• and
• the additive machining process including at least one of plasma transfer arc, high velocity oxygen fuel spraying, laser cladding, laser sintering, arc welding, and additive welding.

A method for manufacturing a piston for use in an internal combustion engine, comprises the steps of:

• forming a crown portion and a skirt portion from a first material,
• forming at least a portion of a combustion surface along the crown portion from a second material by an additive machining process;
• and
• wherein the step of forming the crown portion includes forming an outer rib spaced form a combustion bowl, and the step of forming the combustion surface includes disposing a core material between the outer rib and combustion bowl and applying the second material to the core material.