Thermally insulated runner manifold and injection nozzle construction for plastic molding apparatus

In an injection molding machine system having separable mold tooling including a manifold characterized by hot or cold runner operable for feeding liquefied plastic molding material via a manifold outlet nozzle or bushing to an injection gate of a mold tooling cavity, the improvement in combination therewith of means for maintaining the fluidity of the resident plastic molding material in said manifold and manifold outlet nozzle during closure of the injection gate, thereby enabling use of the resident material in the following molding cycle, said fluidity maintaining means comprising a flow path for the liquefied plastic molding material extending between a manifold inlet sprue, as fed by an associated injection machine ram of the system, and a mold cavity, as fed by said manifold outlet nozzle or bushing at the outlet of a runner of said manifold, said flow path being defined by a pre-formed mold component mounted in said mold tooling and containing a liquid-conducting conduit constructed and arranged for so conducting the liquefied plastic molding material and being constructed of high temperature resistant solid material in a conduit shape having self-supporting structural integrity, said conduit material comprising a non-metallic heat insulation material having a low thermal conductivity to thereby heat insulate the liquefied plastic molding material resident in the conduit flow path such that this resident plastic molding material remains at a reasonable uncured molding temperature for the duration of at least one injection cycle due to the heat insulation characteristics of said fluid flow conduit of the system.