SPLIT THREAD INSERT

A split thread insert is disclosed with integral cooling channels utilized for the continuous internal circulation of cooling fluid around a molding surface of the split thread insert, wherein the molding surface forms a neck area of a preform during an injection molding process. The molding surface of the split thread insert is semi-circular with a profile corresponding with a threaded area of the preform. The split thread insert is assembled from two or more cut pieces, wherein at least one of the cut pieces includes a curved groove formed therein proximate the molding surface for forming a curved cooling fluid channel when the cut pieces are joined to form the split thread insert. The cooling fluid channel includes a flow diverter positioned therein for defining a portion of a continuous cooling fluid circuit of the split thread insert.