When dealing specifically with closure and consumer applications, part and production quality—along with color change performance—are major considerations. Maintaining optimum melt homogeneity is key to achieving this.

Melt channels in the manifold are designed to maintain uniform shear, heat history and eliminate dead spots. Some of the enhanced nozzles on the market mix the melt just before it enters the mold cavity. By redistributing the melt, the interior design creates overlapping melt streams that run over each other to initiate mixing.

Leading hot runner manufacturers are aiming to increase productivity while producing a more structurally sound part. This can result in improvements in several areas: reduction in color change times, elimination of flow lines and greater dimensional stability of parts through more uniform resin temperature distributions. This, in turn, minimizes shrinkage and warpage, providing tighter part tolerances.