Piston having uncoupled skirt

A piston for an engine comprising:

• upper and lower crown portions separately formed and joined by at least one friction weld joint to define a piston head having a closed piston cooling gallery, said piston head having an outer annular ring belt formed with a plurality of piston ring grooves and including a lower end;
• said lower crown portion including a pair of depending pin bosses fabricated of a metallic material and formed with aligned pin bores;
• and
• a pair of piston skirt portions formed as one unitary piece with said pin bores of the same material as said material of said pin bosses, said skirt portions including upper free edges spaced in uncoupled relation to said ring belt and said friction weld joint of said piston head.

A method of forming a piston for an engine, comprising:

• forming an upper crown portion;
• forming a lower crown portion separately from the upper crown portion;
• joining the upper crown portion to the lower crown portion to provide an internal piston cooling gallery between the upper and lower crown portions including a bottom wall of the piston cooling gallery, and to provide an outer annular ring belt portion having a lower end coupled to the bottom wall of the piston cooling gallery;
• forming the lower crown portion with a pair of pin bosses having aligned pin bores;
• and
• forming a piston skirt which is directly and immovably attached to the pin bosses as unitized structure therewith and including an upper free edge that is spaced in uncoupled relation to the ring belt portion and bottom wall of the piston cooling gallery.