Method of manufacturing rubber and polyolefin sole assembly

A method of forming a sole assembly with a mold assembly comprising the steps of:

• using a top plate having a bottom surface and including a movable insert having a bottom surface;
• a middle plate positioned beneath the top plate and having a top surface and a bottom surface, the bottom surface of the movable insert and the top surface of the middle plate cooperating to define an upper recess therebetween;
• and a bottom plate positioned beneath the middle plate and having a top surface, the top surface of the bottom plate and the bottom surface of the middle plate cooperating to define a lower recess therebetween;
• wherein the bottom surface of movable insert and the top surface of the bottom plate are configured such that when the top plate and bottom plate are in contact with one another they cooperate to define a sole recess, the sole recess having a volume that is larger than a volume of the upper recess and a volume of the lower recess combined:
• preheating the bottom plate, middle plate, and top plate;
• placing a quantity of rubber in a first portion of the lower recess;
• placing the lower surface of the middle plate in contact with the upper surface of the bottom plate;
• placing a quantity of a polyolefin in a first portion of the upper recess;
• placing the lower surface of the upper plate in contact with the upper surface of the middle plate;
• subjecting the top plate, middle plate, and bottom plate to heat to semi-cure the rubber in the lower recess to form an outsole member and to semi-cure the polyolefin in the upper recess to form a midsole member;
• separating the top plate, the middle plate, and the bottom plate;
• moving the movable insert upwardly with respect to the top plate;
• placing the lower surface of the top plate in contact with the upper surface of the bottom plate such that the semi-cured polyolefin midsole member contacts the semi-cured rubber outsole member in the sole recess;
• subjecting the top plate and bottom plate to heat such that the polyolefin expands within the sole recess and the polyolefin and rubber in the sole recess fully cure, cross-link, and bond to one another to form a sole assembly for an article of footwear;
• cooling the top plate and the bottom plate;
• and
• removing the top plate from the bottom plate and removing the sole assembly from the sole recess.