Two-piece friction-welded piston

A piston for use in an internal combustion engine, said piston comprising:

• an upper member, said upper member being precision cast to net final dimensions, said upper member having a combustion surface and at least two concentrically positioned upper connecting surfaces spaced apart from said combustion surface;
• and
• a lower member, said lower member being precision cast to net final dimensions, said lower member having a pair of bores formed therethrough for receiving a connecting rod pin, and said lower member having at least two concentrically positioned lower connecting surfaces;
• wherein said lower member is attached to said upper member by way of friction welding such that each upper connecting surface of said upper member forms a welded joint with one of said lower connecting surfaces.

A method of manufacturing a piston comprising:

• precision casting to net final dimensions an upper member, wherein said upper member includes a combustion surface and at least two upper connecting surfaces concentrically arranged and spaced apart from said combustion surface;
• precision casting to net final dimensions a lower member, wherein said lower member includes a pair of opposing skirts having a bore formed through each of said skirts, said lower member also including at least two lower connecting surfaces concentrically arranged;
• and
• friction welding said lower member to said upper member, wherein a welded joint is formed between each of said upper connecting surfaces of said upper member and a corresponding lower connecting surface of said lower member.