Minimum vestige nozzle assembly for plastics injection molding

A nozzle assembly for injecting a plastic resin melt into a mold cavity through a gate, the nozzle assembly comprising:

• a) a nozzle housing defining a hot runner passage therethrough for flowing a plastic resin melt, the hot runner passage having a longitudinal axis;
• and
• a nozzle tip section including a nozzle tip and a hot runner tip passage in flow communication with the hot runner passage for flowing the plastic resin melt, the nozzle tip section being freely slidable relative to the nozzle housing in the hot runner passage along the longitudinal axis during injection of the plastic resin melt into the mold cavity such that axial thermal expansion of the nozzle housing is not imparted to the nozzle tip section, the nozzle tip section including limiting means for limiting axial sliding movement of the nozzle tip section relative to the nozzle housing and to the gate and for limiting the length of the nozzle tip section that can axially thermally expand during injection.

A nozzle assembly for injecting a plastic resin melt into a mold cavity through a gate, the nozzle assembly comprising:

• a) a nozzle housing defining a hot runner passage therethrough for flowing a plastic resin melt, the hot runner passage having a longitudinal axis, the nozzle housing being formed of a first material having a first coefficient of thermal expansion;
• and
• a nozzle tip section including a nozzle tip, the nozzle tip section being freely slidably received in the hot runner passage along the longitudinal axis, the nozzle tip section defining a hot runner tip passage in flow communication with the hot runner passage for flowing the plastic resin melt, the nozzle tip section including a portion formed of a second material having a second coefficient of thermal expansion greater than the first coefficient of thermal expansion such that a plastic resin melt seal is formed between the nozzle tip section and the nozzle housing during injection molding, the nozzle tip section including limiting means for limiting sliding movement of the nozzle tip section along the longitudinal axis relative to the nozzle housing and to the gate and for limiting axial thermal expansion of the nozzle tip section to a lower portion of nozzle tip section including the nozzle tip, during infection of the plastic resin melt into the mold cavity.