Abstract: The present invention is directed to a method and apparatus for using a spiral flow assembly in a polymer extrusion process to make small diameter tubing for such items as wires, cables, and tubing. The invention comprises a mandrel inside of a housing, the mandrel having spiral grooves located on its external surface. A polymer melt is introduced into the housing through an ingress port and flows into and through the spiral grooves on the outside surface of the mandrel, in what is called “groove flow” or “channel flow.” As the polymer melt flows through the grooves or channels, the housing and mandrel begin to separate by either having the housing taper outwardly, becoming gradually larger in diameter along the axial distance of the mandrel or having the mandrel begin to taper inwardly, becoming gradually smaller in diameter along the axial distance of the mandrel.

Abstract: The present invention is a breaker plate which is placed in the path of a polymer melt flow. The breaker plate has a cone-shaped center portion with holes therein, the cone-shaped center portion extending in a downstream direction of the polymer flow. The cone-shaped center portion decreases the downstream melt volume, provides a self-wiping surface on the downstream side so that no polymer accumulates and promotes the transition from a reverse velocity profile to a normal velocity profile.