Precise control non-return valve

An improved precise control non-return valve assembly which is mounted on the front end of a helical rotating plasticating screw of an injection molding machine or the like that is surrounded by a heated elongated barrel and end-cap that forms a distribution chamber, whose purpose is to allow means for passage of molten plastic fluid in the downstream direction while preventing it in the opposite direction. The valve having an outwardly extended portion of a shaft and has a means to accept a ring that is sandwiched between a bushing assembly and a rear seating area. The bushing assembly consists of at least two bushings and one pin whose dual purpose is to govern the forward movement of the ring and to absorb the force that is being applied to it. The non-return valve assembly when moved forward with the screw, forms a seal, builds pressure, and displaces molten plastic fluid from the distribution chamber through a discharge chamber passageway and into a mold.